Field Summary

Constructor Summary

Method Summary

Field Details

• CASE_INSENSITIVE_ORDER

  public static final Comparator<String> CASE_INSENSITIVE_ORDER

  A Comparator that ordersString objects as bycompareToIgnoreCase. This comparator is serializable.

  Note that this Comparator doesnot take locale into account, and will result in an unsatisfactory ordering for certain locales. TheCollator class provides locale-sensitive comparison.

  Since:

  1.2

  See Also:

  • Collator

Constructor Details

• String

  public String()

  Initializes a newly createdString object so that it represents an empty character sequence. Note that use of this constructor is unnecessary since Strings are immutable.

• String

  public String(String original)

  Initializes a newly createdString object so that it represents the same sequence of characters as the argument; in other words, the newly created string is a copy of the argument string. Unless an explicit copy oforiginal is needed, use of this constructor is unnecessary since Strings are immutable.

  Parameters:

  original - AString

• String

  public String(char[] value)

  Allocates a newString so that it represents the sequence of characters currently contained in the character array argument. The contents of the character array are copied; subsequent modification of the character array does not affect the newly created string.

  The contents of the string are unspecified if the character array is modified during string construction.

  Parameters:

  value - The initial value of the string

• String

  public String(char[] value, int offset, int count)

  Allocates a newString that contains characters from a subarray of the character array argument. Theoffset argument is the index of the first character of the subarray and thecount argument specifies the length of the subarray. The contents of the subarray are copied; subsequent modification of the character array does not affect the newly created string.

  The contents of the string are unspecified if the character array is modified during string construction.

  Parameters:

  value - Array that is the source of characters

  offset - The initial offset

  count - The length

  Throws:

  IndexOutOfBoundsException - Ifoffset is negative,count is negative, oroffset is greater thanvalue.length - count

• String

  public String(int[] codePoints, int offset, int count)

  Allocates a newString that contains characters from a subarray of theUnicode code point array argument. Theoffset argument is the index of the first code point of the subarray and thecount argument specifies the length of the subarray. The contents of the subarray are converted tochars; subsequent modification of theint array does not affect the newly created string.

  The contents of the string are unspecified if the codepoints array is modified during string construction.

  Parameters:

  codePoints - Array that is the source of Unicode code points

  offset - The initial offset

  count - The length

  Throws:

  IllegalArgumentException - If any invalid Unicode code point is found in codePoints

  IndexOutOfBoundsException - Ifoffset is negative,count is negative, oroffset is greater thancodePoints.length - count

  Since:

  1.5

• String

  @Deprecated(since="1.1")public String(byte[] ascii, int hibyte, int offset, int count)

  Deprecated.

  This method does not properly convert bytes into characters. As of JDK 1.1, the preferred way to do this is via theString constructors that take aCharset, charset name, or that use thedefault charset.

  Allocates a newString constructed from a subarray of an array of 8-bit integer values.

  Theoffset argument is the index of the first byte of the subarray, and thecount argument specifies the length of the subarray.

  Eachbyte in the subarray is converted to achar as specified in theString(byte[],int) constructor.

  The contents of the string are unspecified if the byte array is modified during string construction.

  Parameters:

  ascii - The bytes to be converted to characters

  hibyte - The top 8 bits of each 16-bit Unicode code unit

  offset - The initial offset

  count - The length

  Throws:

  IndexOutOfBoundsException - Ifoffset is negative,count is negative, oroffset is greater thanascii.length - count

  See Also:

  • String(byte[], int)
  • String(byte[], int, int, java.lang.String)
  • String(byte[], int, int, java.nio.charset.Charset)
  • String(byte[], int, int)
  • String(byte[], java.lang.String)
  • String(byte[], java.nio.charset.Charset)
  • String(byte[])

• String

  @Deprecated(since="1.1")public String(byte[] ascii, int hibyte)

  Deprecated.

  This method does not properly convert bytes into characters. As of JDK 1.1, the preferred way to do this is via theString constructors that take aCharset, charset name, or that use thedefault charset.

  Allocates a newString containing characters constructed from an array of 8-bit integer values. Each characterc in the resulting string is constructed from the corresponding componentb in the byte array such that:

  c == (char)(((hibyte & 0xff) << 8)                         | (b & 0xff))

  The contents of the string are unspecified if the byte array is modified during string construction.

  Parameters:

  ascii - The bytes to be converted to characters

  hibyte - The top 8 bits of each 16-bit Unicode code unit

  See Also:

  • String(byte[], int, int, java.lang.String)
  • String(byte[], int, int, java.nio.charset.Charset)
  • String(byte[], int, int)
  • String(byte[], java.lang.String)
  • String(byte[], java.nio.charset.Charset)
  • String(byte[])

• String

  public String(byte[] bytes, int offset, int length,String charsetName) throwsUnsupportedEncodingException

  Constructs a newString by decoding the specified subarray of bytes using the specified charset. The length of the newString is a function of the charset, and hence may not be equal to the length of the subarray.

  The behavior of this constructor when the given bytes are not valid in the given charset is unspecified. TheCharsetDecoder class should be used when more control over the decoding process is required.

  The contents of the string are unspecified if the byte array is modified during string construction.

  Parameters:

  bytes - The bytes to be decoded into characters

  offset - The index of the first byte to decode

  length - The number of bytes to decode

  charsetName - The name of a supportedcharset

  Throws:

  UnsupportedEncodingException - If the named charset is not supported

  IndexOutOfBoundsException - Ifoffset is negative,length is negative, oroffset is greater thanbytes.length - length

  Since:

  1.1

• String

  public String(byte[] bytes, int offset, int length,Charset charset)

  Constructs a newString by decoding the specified subarray of bytes using the specifiedcharset. The length of the newString is a function of the charset, and hence may not be equal to the length of the subarray.

  This method always replaces malformed-input and unmappable-character sequences with this charset's default replacement string. TheCharsetDecoder class should be used when more control over the decoding process is required.

  The contents of the string are unspecified if the byte array is modified during string construction.

  Parameters:

  bytes - The bytes to be decoded into characters

  offset - The index of the first byte to decode

  length - The number of bytes to decode

  charset - Thecharset to be used to decode thebytes

  Throws:

  IndexOutOfBoundsException - Ifoffset is negative,length is negative, oroffset is greater thanbytes.length - length

  Since:

  1.6

• String

  public String(byte[] bytes,String charsetName) throwsUnsupportedEncodingException

  Constructs a newString by decoding the specified array of bytes using the specifiedcharset. The length of the newString is a function of the charset, and hence may not be equal to the length of the byte array.

  The behavior of this constructor when the given bytes are not valid in the given charset is unspecified. TheCharsetDecoder class should be used when more control over the decoding process is required.

  The contents of the string are unspecified if the byte array is modified during string construction.

  Parameters:

  bytes - The bytes to be decoded into characters

  charsetName - The name of a supportedcharset

  Throws:

  UnsupportedEncodingException - If the named charset is not supported

  Since:

  1.1

• String

  public String(byte[] bytes,Charset charset)

  Constructs a newString by decoding the specified array of bytes using the specifiedcharset. The length of the newString is a function of the charset, and hence may not be equal to the length of the byte array.

  This method always replaces malformed-input and unmappable-character sequences with this charset's default replacement string. TheCharsetDecoder class should be used when more control over the decoding process is required.

  The contents of the string are unspecified if the byte array is modified during string construction.

  Parameters:

  bytes - The bytes to be decoded into characters

  charset - Thecharset to be used to decode thebytes

  Since:

  1.6

• String

  public String(byte[] bytes, int offset, int length)

  Constructs a newString by decoding the specified subarray of bytes using thedefault charset. The length of the newString is a function of the charset, and hence may not be equal to the length of the subarray.

  The behavior of this constructor when the given bytes are not valid in the default charset is unspecified. TheCharsetDecoder class should be used when more control over the decoding process is required.

  The contents of the string are unspecified if the byte array is modified during string construction.

  Parameters:

  bytes - The bytes to be decoded into characters

  offset - The index of the first byte to decode

  length - The number of bytes to decode

  Throws:

  IndexOutOfBoundsException - Ifoffset is negative,length is negative, oroffset is greater thanbytes.length - length

  Since:

  1.1

• String

  public String(byte[] bytes)

  Constructs a newString by decoding the specified array of bytes using thedefault charset. The length of the newString is a function of the charset, and hence may not be equal to the length of the byte array.

  The behavior of this constructor when the given bytes are not valid in the default charset is unspecified. TheCharsetDecoder class should be used when more control over the decoding process is required.

  The contents of the string are unspecified if the byte array is modified during string construction.

  Parameters:

  bytes - The bytes to be decoded into characters

  Since:

  1.1

• String

  public String(StringBuffer buffer)

  Allocates a new string that contains the sequence of characters currently contained in the string buffer argument. The contents of the string buffer are copied; subsequent modification of the string buffer does not affect the newly created string.

  Parameters:

  buffer - AStringBuffer

• String

  public String(StringBuilder builder)

  Allocates a new string that contains the sequence of characters currently contained in the string builder argument. The contents of the string builder are copied; subsequent modification of the string builder does not affect the newly created string.

  The contents of the string are unspecified if theStringBuilder is modified during string construction.

  This constructor is provided to ease migration to StringBuilder. Obtaining a string from a string builder via the toString method is likely to run faster and is generally preferred.

  Parameters:

  builder - AStringBuilder

  Since:

  1.5

Method Details

• length

  public int length()

  Returns the length of this string. The length is equal to the number ofUnicode code units in the string.

  Specified by:

  length in interface CharSequence

  Returns:

  the length of the sequence of characters represented by this object.

• isEmpty

  public boolean isEmpty()

  Returnstrue if, and only if,length() is0.

  Specified by:

  isEmpty in interface CharSequence

  Returns:

  true iflength() is0, otherwisefalse

  Since:

  1.6

• charAt

  public char charAt(int index)

  Returns thechar value at the specified index. An index ranges from0 tolength() - 1. The firstchar value of the sequence is at index0, the next at index1, and so on, as for array indexing.

  If thechar value specified by the index is asurrogate, the surrogate value is returned.

  Specified by:

  charAt in interface CharSequence

  Parameters:

  index - the index of thechar value.

  Returns:

  thechar value at the specified index of this string. The firstchar value is at index0.

  Throws:

  IndexOutOfBoundsException - if theindex argument is negative or not less than the length of this string.

• codePointAt

  public int codePointAt(int index)

  Returns the character (Unicode code point) at the specified index. The index refers tochar values (Unicode code units) and ranges from0 tolength() - 1.

  If thechar value specified at the given index is in the high-surrogate range, the following index is less than the length of thisString, and thechar value at the following index is in the low-surrogate range, then the supplementary code point corresponding to this surrogate pair is returned. Otherwise, thechar value at the given index is returned.

  Parameters:

  index - the index to thechar values

  Returns:

  the code point value of the character at theindex

  Throws:

  IndexOutOfBoundsException - if theindex argument is negative or not less than the length of this string.

  Since:

  1.5

• codePointBefore

  public int codePointBefore(int index)

  Returns the character (Unicode code point) before the specified index. The index refers tochar values (Unicode code units) and ranges from1 tolength.

  If thechar value at(index - 1) is in the low-surrogate range,(index - 2) is not negative, and thechar value at(index - 2) is in the high-surrogate range, then the supplementary code point value of the surrogate pair is returned. If thechar value atindex - 1 is an unpaired low-surrogate or a high-surrogate, the surrogate value is returned.

  Parameters:

  index - the index following the code point that should be returned

  Returns:

  the Unicode code point value before the given index.

  Throws:

  IndexOutOfBoundsException - if theindex argument is less than 1 or greater than the length of this string.

  Since:

  1.5

• codePointCount

  public int codePointCount(int beginIndex, int endIndex)

  Returns the number of Unicode code points in the specified text range of thisString. The text range begins at the specifiedbeginIndex and extends to thechar at indexendIndex - 1. Thus the length (inchars) of the text range isendIndex-beginIndex. Unpaired surrogates within the text range count as one code point each.

  Parameters:

  beginIndex - the index to the firstchar of the text range.

  endIndex - the index after the lastchar of the text range.

  Returns:

  the number of Unicode code points in the specified text range

  Throws:

  IndexOutOfBoundsException - if thebeginIndex is negative, orendIndex is larger than the length of thisString, orbeginIndex is larger thanendIndex.

  Since:

  1.5

• offsetByCodePoints

  public int offsetByCodePoints(int index, int codePointOffset)

  Returns the index within thisString that is offset from the givenindex bycodePointOffset code points. Unpaired surrogates within the text range given byindex andcodePointOffset count as one code point each.

  Parameters:

  index - the index to be offset

  codePointOffset - the offset in code points

  Returns:

  the index within thisString

  Throws:

  IndexOutOfBoundsException - ifindex is negative or larger than the length of thisString, or ifcodePointOffset is positive and the substring starting withindex has fewer thancodePointOffset code points, or ifcodePointOffset is negative and the substring beforeindex has fewer than the absolute value ofcodePointOffset code points.

  Since:

  1.5

• getChars

  public void getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin)

  Copies characters from this string into the destination character array.

  The first character to be copied is at indexsrcBegin; the last character to be copied is at indexsrcEnd-1 (thus the total number of characters to be copied issrcEnd-srcBegin). The characters are copied into the subarray ofdst starting at indexdstBegin and ending at index:

       dstBegin + (srcEnd-srcBegin) - 1

  Parameters:

  srcBegin - index of the first character in the string to copy.

  srcEnd - index after the last character in the string to copy.

  dst - the destination array.

  dstBegin - the start offset in the destination array.

  Throws:

  IndexOutOfBoundsException - If any of the following is true:

  • srcBegin is negative.
  • srcBegin is greater thansrcEnd
  • srcEnd is greater than the length of this string
  • dstBegin is negative
  • dstBegin+(srcEnd-srcBegin) is larger thandst.length

• getBytes

  @Deprecated(since="1.1")public void getBytes(int srcBegin, int srcEnd, byte[] dst, int dstBegin)

  Deprecated.

  This method does not properly convert characters into bytes. As of JDK 1.1, the preferred way to do this is via thegetBytes() method, which uses thedefault charset.

  Copies characters from this string into the destination byte array. Each byte receives the 8 low-order bits of the corresponding character. The eight high-order bits of each character are not copied and do not participate in the transfer in any way.

  The first character to be copied is at indexsrcBegin; the last character to be copied is at indexsrcEnd-1. The total number of characters to be copied issrcEnd-srcBegin. The characters, converted to bytes, are copied into the subarray of dst starting at indexdstBegin and ending at index:

       dstBegin + (srcEnd-srcBegin) - 1

  Parameters:

  srcBegin - Index of the first character in the string to copy

  srcEnd - Index after the last character in the string to copy

  dst - The destination array

  dstBegin - The start offset in the destination array

  Throws:

  IndexOutOfBoundsException - If any of the following is true:

  • srcBegin is negative
  • srcBegin is greater thansrcEnd
  • srcEnd is greater than the length of this String
  • dstBegin is negative
  • dstBegin+(srcEnd-srcBegin) is larger than dst.length

• getBytes

  public byte[] getBytes(String charsetName) throwsUnsupportedEncodingException

  Encodes thisString into a sequence of bytes using the named charset, storing the result into a new byte array.

  The behavior of this method when this string cannot be encoded in the given charset is unspecified. TheCharsetEncoder class should be used when more control over the encoding process is required.

  Parameters:

  charsetName - The name of a supportedcharset

  Returns:

  The resultant byte array

  Throws:

  UnsupportedEncodingException - If the named charset is not supported

  Since:

  1.1

• getBytes

  public byte[] getBytes(Charset charset)

  Encodes thisString into a sequence of bytes using the givencharset, storing the result into a new byte array.

  This method always replaces malformed-input and unmappable-character sequences with this charset's default replacement byte array. TheCharsetEncoder class should be used when more control over the encoding process is required.

  Parameters:

  charset - TheCharset to be used to encode theString

  Returns:

  The resultant byte array

  Since:

  1.6

• getBytes

  public byte[] getBytes()

  Encodes thisString into a sequence of bytes using thedefault charset, storing the result into a new byte array.

  The behavior of this method when this string cannot be encoded in the default charset is unspecified. TheCharsetEncoder class should be used when more control over the encoding process is required.

  Returns:

  The resultant byte array

  Since:

  1.1

• equals

  public boolean equals(Object anObject)

  Compares this string to the specified object. The result is true if and only if the argument is notnull and is a String object that represents the same sequence of characters as this object.

  For finer-grained String comparison, refer toCollator.

  Overrides:

  equals in class Object

  Parameters:

  anObject - The object to compare thisString against

  Returns:

  true if the given object represents aString equivalent to this string,false otherwise

  See Also:

  • compareTo(String)
  • equalsIgnoreCase(String)

• contentEquals

  public boolean contentEquals(StringBuffer sb)

  Compares this string to the specifiedStringBuffer. The result istrue if and only if thisString represents the same sequence of characters as the specifiedStringBuffer. This method synchronizes on theStringBuffer.

  For finer-grained String comparison, refer toCollator.

  Parameters:

  sb - TheStringBuffer to compare thisString against

  Returns:

  true if thisString represents the same sequence of characters as the specifiedStringBuffer,false otherwise

  Since:

  1.4

• contentEquals

  public boolean contentEquals(CharSequence cs)

  Compares this string to the specifiedCharSequence. The result istrue if and only if thisString represents the same sequence of char values as the specified sequence. Note that if theCharSequence is aStringBuffer then the method synchronizes on it.

  For finer-grained String comparison, refer toCollator.

  Parameters:

  cs - The sequence to compare thisString against

  Returns:

  true if thisString represents the same sequence of char values as the specified sequence, false otherwise

  Since:

  1.5

• equalsIgnoreCase

  public boolean equalsIgnoreCase(String anotherString)

  Compares thisString to anotherString, ignoring case considerations. Two strings are considered equal ignoring case if they are of the same length and corresponding Unicode code points in the two strings are equal ignoring case.

  Two Unicode code points are considered the same ignoring case if at least one of the following is true:

  • The two Unicode code points are the same (as compared by the== operator)
  • CallingCharacter.toLowerCase(Character.toUpperCase(int)) on each Unicode code point produces the same result

  Note that this method doesnot take locale into account, and will result in unsatisfactory results for certain locales. TheCollator class provides locale-sensitive comparison.

  Parameters:

  anotherString - TheString to compare thisString against

  Returns:

  true if the argument is notnull and it represents an equivalentString ignoring case; false otherwise

  See Also:

  • equals(Object)
  • codePoints()

• compareTo

  public int compareTo(String anotherString)

  Compares two strings lexicographically. The comparison is based on the Unicode value of each character in the strings. The character sequence represented by thisString object is compared lexicographically to the character sequence represented by the argument string. The result is a negative integer if thisString object lexicographically precedes the argument string. The result is a positive integer if thisString object lexicographically follows the argument string. The result is zero if the strings are equal;compareTo returns0 exactly when theequals(Object) method would returntrue.

  This is the definition of lexicographic ordering. If two strings are different, then either they have different characters at some index that is a valid index for both strings, or their lengths are different, or both. If they have different characters at one or more index positions, letk be the smallest such index; then the string whose character at positionk has the smaller value, as determined by using the< operator, lexicographically precedes the other string. In this case,compareTo returns the difference of the two character values at positionk in the two string -- that is, the value:

   this.charAt(k)-anotherString.charAt(k)

  If there is no index position at which they differ, then the shorter string lexicographically precedes the longer string. In this case,compareTo returns the difference of the lengths of the strings -- that is, the value:

   this.length()-anotherString.length()

  For finer-grained String comparison, refer toCollator.

  Specified by:

  compareTo in interface Comparable<String>

  Parameters:

  anotherString - theString to be compared.

  Returns:

  the value0 if the argument string is equal to this string; a value less than0 if this string is lexicographically less than the string argument; and a value greater than0 if this string is lexicographically greater than the string argument.

• compareToIgnoreCase

  public int compareToIgnoreCase(String str)

  Compares two strings lexicographically, ignoring case differences. This method returns an integer whose sign is that of callingcompareTo with case folded versions of the strings where case differences have been eliminated by callingCharacter.toLowerCase(Character.toUpperCase(int)) on each Unicode code point.

  Note that this method doesnot take locale into account, and will result in an unsatisfactory ordering for certain locales. TheCollator class provides locale-sensitive comparison.

  Parameters:

  str - theString to be compared.

  Returns:

  a negative integer, zero, or a positive integer as the specified String is greater than, equal to, or less than this String, ignoring case considerations.

  Since:

  1.2

  See Also:

  • Collator
  • codePoints()

• regionMatches

  public boolean regionMatches(int toffset,String other, int ooffset, int len)

  Tests if two string regions are equal.

  A substring of thisString object is compared to a substring of the argument other. The result is true if these substrings represent identical character sequences. The substring of thisString object to be compared begins at indextoffset and has lengthlen. The substring of other to be compared begins at indexooffset and has lengthlen. The result isfalse if and only if at least one of the following is true:

  • toffset is negative.
  • ooffset is negative.
  • toffset+len is greater than the length of thisString object.
  • ooffset+len is greater than the length of the other argument.
  • There is some nonnegative integerk less thanlen such that:this.charAt(toffset +k) != other.charAt(ooffset +k)

  Note that this method doesnot take locale into account. TheCollator class provides locale-sensitive comparison.

  Parameters:

  toffset - the starting offset of the subregion in this string.

  other - the string argument.

  ooffset - the starting offset of the subregion in the string argument.

  len - the number of characters to compare.

  Returns:

  true if the specified subregion of this string exactly matches the specified subregion of the string argument;false otherwise.

• regionMatches

  public boolean regionMatches(boolean ignoreCase, int toffset,String other, int ooffset, int len)

  Tests if two string regions are equal.

  A substring of thisString object is compared to a substring of the argumentother. The result istrue if these substrings represent Unicode code point sequences that are the same, ignoring case if and only ifignoreCase is true. The sequencestsequence andosequence are compared, wheretsequence is the sequence produced as if by callingthis.substring(toffset, toffset + len).codePoints() andosequence is the sequence produced as if by callingother.substring(ooffset, ooffset + len).codePoints(). The result istrue if and only if all of the following are true:

  • toffset is non-negative.
  • ooffset is non-negative.
  • toffset+len is less than or equal to the length of thisString object.
  • ooffset+len is less than or equal to the length of the other argument.
  • ifignoreCase isfalse, all pairs of corresponding Unicode code points are equal integer values; or ifignoreCase istrue,Character.toLowerCase(Character.toUpperCase(int)) on all pairs of Unicode code points results in equal integer values.

  Note that this method doesnot take locale into account, and will result in unsatisfactory results for certain locales whenignoreCase istrue. TheCollator class provides locale-sensitive comparison.

  Parameters:

  ignoreCase - iftrue, ignore case when comparing characters.

  toffset - the starting offset of the subregion in this string.

  other - the string argument.

  ooffset - the starting offset of the subregion in the string argument.

  len - the number of characters (Unicode code units - 16bitchar value) to compare.

  Returns:

  true if the specified subregion of this string matches the specified subregion of the string argument;false otherwise. Whether the matching is exact or case insensitive depends on theignoreCase argument.

  See Also:

  • codePoints()

• startsWith

  public boolean startsWith(String prefix, int toffset)

  Tests if the substring of this string beginning at the specified index starts with the specified prefix.

  Parameters:

  prefix - the prefix.

  toffset - where to begin looking in this string.

  Returns:

  true if the character sequence represented by the argument is a prefix of the substring of this object starting at indextoffset;false otherwise. The result isfalse iftoffset is negative or greater than the length of thisString object; otherwise the result is the same as the result of the expression

            this.substring(toffset).startsWith(prefix)

• startsWith

  public boolean startsWith(String prefix)

  Tests if this string starts with the specified prefix.

  Parameters:

  prefix - the prefix.

  Returns:

  true if the character sequence represented by the argument is a prefix of the character sequence represented by this string;false otherwise. Note also thattrue will be returned if the argument is an empty string or is equal to thisString object as determined by theequals(Object) method.

  Since:

  1.0

• endsWith

  public boolean endsWith(String suffix)

  Tests if this string ends with the specified suffix.

  Parameters:

  suffix - the suffix.

  Returns:

  true if the character sequence represented by the argument is a suffix of the character sequence represented by this object;false otherwise. Note that the result will betrue if the argument is the empty string or is equal to thisString object as determined by theequals(Object) method.

• hashCode

  public int hashCode()

  Returns a hash code for this string. The hash code for aString object is computed as

   s[0]*31^(n-1) + s[1]*31^(n-2) + ... + s[n-1]

  usingint arithmetic, wheres[i] is theith character of the string,n is the length of the string, and^ indicates exponentiation. (The hash value of the empty string is zero.)

  Overrides:

  hashCode in class Object

  Returns:

  a hash code value for this object.

  See Also:

  • Object.equals(java.lang.Object)
  • System.identityHashCode(java.lang.Object)

• indexOf

  public int indexOf(int ch)

  Returns the index within this string of the first occurrence of the specified character. If a character with valuech occurs in the character sequence represented by thisString object, then the index (in Unicode code units) of the first such occurrence is returned. For values ofch in the range from 0 to 0xFFFF (inclusive), this is the smallest valuek such that:

   this.charAt(k) == ch

  is true. For other values ofch, it is the smallest valuek such that:

   this.codePointAt(k) == ch

  is true. In either case, if no such character occurs in this string, then-1 is returned.

  Parameters:

  ch - a character (Unicode code point).

  Returns:

  the index of the first occurrence of the character in the character sequence represented by this object, or-1 if the character does not occur.

• indexOf

  public int indexOf(int ch, int fromIndex)

  Returns the index within this string of the first occurrence of the specified character, starting the search at the specified index.

  If a character with valuech occurs in the character sequence represented by thisString object at an index no smaller thanfromIndex, then the index of the first such occurrence is returned. For values ofch in the range from 0 to 0xFFFF (inclusive), this is the smallest valuek such that:

   (this.charAt(k) == ch)&& (k >= fromIndex)

  is true. For other values ofch, it is the smallest valuek such that:

   (this.codePointAt(k) == ch)&& (k >= fromIndex)

  is true. In either case, if no such character occurs in this string at or after positionfromIndex, then-1 is returned.

  There is no restriction on the value offromIndex. If it is negative, it has the same effect as if it were zero: this entire string may be searched. If it is greater than the length of this string, it has the same effect as if it were equal to the length of this string:-1 is returned.

  All indices are specified inchar values (Unicode code units).

  API Note:

  Unlikesubstring(int), for example, this method does not throw an exception whenfromIndex is outside the valid range. Rather, it returns -1 whenfromIndex is larger than the length of the string. This result is, by itself, indistinguishable from a genuine absence ofch in the string. If stricter behavior is needed,indexOf(int, int, int) should be considered instead. On aStrings, for example,s.indexOf(ch, fromIndex, s.length()) would throw iffromIndex were larger than the string length, or were negative.

  Parameters:

  ch - a character (Unicode code point).

  fromIndex - the index to start the search from.

  Returns:

  the index of the first occurrence of the character in the character sequence represented by this object that is greater than or equal tofromIndex, or-1 if the character does not occur.

• indexOf

  public int indexOf(int ch, int beginIndex, int endIndex)

  Returns the index within this string of the first occurrence of the specified character, starting the search atbeginIndex and stopping beforeendIndex.

  If a character with valuech occurs in the character sequence represented by thisString object at an index no smaller thanbeginIndex but smaller thanendIndex, then the index of the first such occurrence is returned. For values ofch in the range from 0 to 0xFFFF (inclusive), this is the smallest valuek such that:

   (this.charAt(k) == ch) && (beginIndex <=k < endIndex)

  is true. For other values ofch, it is the smallest valuek such that:

   (this.codePointAt(k) == ch) && (beginIndex <=k < endIndex)

  is true. In either case, if no such character occurs in this string at or after positionbeginIndex and before positionendIndex, then-1 is returned.

  All indices are specified inchar values (Unicode code units).

  Parameters:

  ch - a character (Unicode code point).

  beginIndex - the index to start the search from (included).

  endIndex - the index to stop the search at (excluded).

  Returns:

  the index of the first occurrence of the character in the character sequence represented by this object that is greater than or equal tobeginIndex and less thanendIndex, or-1 if the character does not occur.

  Throws:

  StringIndexOutOfBoundsException - ifbeginIndex is negative, orendIndex is larger than the length of thisString object, orbeginIndex is larger thanendIndex.

  Since:

  21

• lastIndexOf

  public int lastIndexOf(int ch)

  Returns the index within this string of the last occurrence of the specified character. For values ofch in the range from 0 to 0xFFFF (inclusive), the index (in Unicode code units) returned is the largest valuek such that:

   this.charAt(k) == ch

  is true. For other values ofch, it is the largest valuek such that:

   this.codePointAt(k) == ch

  is true. In either case, if no such character occurs in this string, then-1 is returned. TheString is searched backwards starting at the last character.

  Parameters:

  ch - a character (Unicode code point).

  Returns:

  the index of the last occurrence of the character in the character sequence represented by this object, or-1 if the character does not occur.

• lastIndexOf

  public int lastIndexOf(int ch, int fromIndex)

  Returns the index within this string of the last occurrence of the specified character, searching backward starting at the specified index. For values ofch in the range from 0 to 0xFFFF (inclusive), the index returned is the largest valuek such that:

   (this.charAt(k) == ch)&& (k <= fromIndex)

  is true. For other values ofch, it is the largest valuek such that:

   (this.codePointAt(k) == ch)&& (k <= fromIndex)

  is true. In either case, if no such character occurs in this string at or before positionfromIndex, then-1 is returned.

  All indices are specified inchar values (Unicode code units).

  Parameters:

  ch - a character (Unicode code point).

  fromIndex - the index to start the search from. There is no restriction on the value offromIndex. If it is greater than or equal to the length of this string, it has the same effect as if it were equal to one less than the length of this string: this entire string may be searched. If it is negative, it has the same effect as if it were -1: -1 is returned.

  Returns:

  the index of the last occurrence of the character in the character sequence represented by this object that is less than or equal tofromIndex, or-1 if the character does not occur before that point.

• indexOf

  public int indexOf(String str)

  Returns the index within this string of the first occurrence of the specified substring.

  The returned index is the smallest valuek for which:

   this.startsWith(str, k)

  If no such value ofk exists, then-1 is returned.

  Parameters:

  str - the substring to search for.

  Returns:

  the index of the first occurrence of the specified substring, or-1 if there is no such occurrence.

• indexOf

  public int indexOf(String str, int fromIndex)

  Returns the index within this string of the first occurrence of the specified substring, starting at the specified index.

  The returned index is the smallest valuek for which:

       k >= Math.min(fromIndex, this.length()) &&                   this.startsWith(str, k)

  If no such value ofk exists, then-1 is returned.

  API Note:

  Unlikesubstring(int), for example, this method does not throw an exception whenfromIndex is outside the valid range. Rather, it returns -1 whenfromIndex is larger than the length of the string. This result is, by itself, indistinguishable from a genuine absence ofstr in the string. If stricter behavior is needed,indexOf(String, int, int) should be considered instead. OnStrings and a non-emptystr, for example,s.indexOf(str, fromIndex, s.length()) would throw iffromIndex were larger than the string length, or were negative.

  Parameters:

  str - the substring to search for.

  fromIndex - the index from which to start the search.

  Returns:

  the index of the first occurrence of the specified substring, starting at the specified index, or-1 if there is no such occurrence.

• indexOf

  public int indexOf(String str, int beginIndex, int endIndex)

  Returns the index of the first occurrence of the specified substring within the specified index range ofthis string.

  This method returns the same result as the one of the invocation

       s.substring(beginIndex, endIndex).indexOf(str) + beginIndex

  if the index returned byindexOf(String) is non-negative, and returns -1 otherwise. (No substring is instantiated, though.)

  Parameters:

  str - the substring to search for.

  beginIndex - the index to start the search from (included).

  endIndex - the index to stop the search at (excluded).

  Returns:

  the index of the first occurrence of the specified substring within the specified index range, or-1 if there is no such occurrence.

  Throws:

  StringIndexOutOfBoundsException - ifbeginIndex is negative, orendIndex is larger than the length of thisString object, orbeginIndex is larger thanendIndex.

  Since:

  21

• lastIndexOf

  public int lastIndexOf(String str)

  Returns the index within this string of the last occurrence of the specified substring. The last occurrence of the empty string "" is considered to occur at the index valuethis.length().

  The returned index is the largest valuek for which:

   this.startsWith(str, k)

  If no such value ofk exists, then-1 is returned.

  Parameters:

  str - the substring to search for.

  Returns:

  the index of the last occurrence of the specified substring, or-1 if there is no such occurrence.

• lastIndexOf

  public int lastIndexOf(String str, int fromIndex)

  Returns the index within this string of the last occurrence of the specified substring, searching backward starting at the specified index.

  The returned index is the largest valuek for which:

       k <= Math.min(fromIndex, this.length()) &&                   this.startsWith(str, k)

  If no such value ofk exists, then-1 is returned.

  Parameters:

  str - the substring to search for.

  fromIndex - the index to start the search from.

  Returns:

  the index of the last occurrence of the specified substring, searching backward from the specified index, or-1 if there is no such occurrence.

• substring

  public String substring(int beginIndex)

  Returns a string that is a substring of this string. The substring begins with the character at the specified index and extends to the end of this string.

  Examples:

   "unhappy".substring(2) returns "happy" "Harbison".substring(3) returns "bison" "emptiness".substring(9) returns "" (an empty string)

  Parameters:

  beginIndex - the beginning index, inclusive.

  Returns:

  the specified substring.

  Throws:

  IndexOutOfBoundsException - ifbeginIndex is negative or larger than the length of thisString object.

• substring

  public String substring(int beginIndex, int endIndex)

  Returns a string that is a substring of this string. The substring begins at the specifiedbeginIndex and extends to the character at indexendIndex - 1. Thus the length of the substring isendIndex-beginIndex.

  Examples:

   "hamburger".substring(4, 8) returns "urge" "smiles".substring(1, 5) returns "mile"

  Parameters:

  beginIndex - the beginning index, inclusive.

  endIndex - the ending index, exclusive.

  Returns:

  the specified substring.

  Throws:

  IndexOutOfBoundsException - if thebeginIndex is negative, orendIndex is larger than the length of thisString object, orbeginIndex is larger thanendIndex.

• subSequence

  public CharSequence subSequence(int beginIndex, int endIndex)

  Returns a character sequence that is a subsequence of this sequence.

  An invocation of this method of the form

   str.subSequence(begin, end)

  behaves in exactly the same way as the invocation

   str.substring(begin, end)

  Specified by:

  subSequence in interface CharSequence

  API Note:

  This method is defined so that theString class can implement theCharSequence interface.

  Parameters:

  beginIndex - the begin index, inclusive.

  endIndex - the end index, exclusive.

  Returns:

  the specified subsequence.

  Throws:

  IndexOutOfBoundsException - ifbeginIndex orendIndex is negative, ifendIndex is greater thanlength(), or ifbeginIndex is greater thanendIndex

  Since:

  1.4

• concat

  public String concat(String str)

  Concatenates the specified string to the end of this string.

  If the length of the argument string is0, then thisString object is returned. Otherwise, aString object is returned that represents a character sequence that is the concatenation of the character sequence represented by thisString object and the character sequence represented by the argument string.

  Examples:

   "cares".concat("s") returns "caress" "to".concat("get").concat("her") returns "together"

  Parameters:

  str - theString that is concatenated to the end of thisString.

  Returns:

  a string that represents the concatenation of this object's characters followed by the string argument's characters.

• replace

  public String replace(char oldChar, char newChar)

  Returns a string resulting from replacing all occurrences ofoldChar in this string withnewChar.

  If the characteroldChar does not occur in the character sequence represented by thisString object, then a reference to thisString object is returned. Otherwise, aString object is returned that represents a character sequence identical to the character sequence represented by thisString object, except that every occurrence ofoldChar is replaced by an occurrence ofnewChar.

  Examples:

   "mesquite in your cellar".replace('e', 'o')         returns "mosquito in your collar" "the war of baronets".replace('r', 'y')         returns "the way of bayonets" "sparring with a purple porpoise".replace('p', 't')         returns "starring with a turtle tortoise" "JonL".replace('q', 'x') returns "JonL" (no change)

  Parameters:

  oldChar - the old character.

  newChar - the new character.

  Returns:

  a string derived from this string by replacing every occurrence ofoldChar withnewChar.

• matches

  public boolean matches(String regex)

  Tells whether or not this string matches the givenregular expression.

  An invocation of this method of the formstr.matches(regex) yields exactly the same result as the expression

  Pattern.matches(regex,str)

  Parameters:

  regex - the regular expression to which this string is to be matched

  Returns:

  true if, and only if, this string matches the given regular expression

  Throws:

  PatternSyntaxException - if the regular expression's syntax is invalid

  Since:

  1.4

  See Also:

  • Pattern

• contains

  public boolean contains(CharSequence s)

  Returns true if and only if this string contains the specified sequence of char values.

  Parameters:

  s - the sequence to search for

  Returns:

  true if this string containss, false otherwise

  Since:

  1.5

• replaceFirst

  public String replaceFirst(String regex,String replacement)

  Replaces the first substring of this string that matches the givenregular expression with the given replacement.

  An invocation of this method of the formstr.replaceFirst(regex,repl) yields exactly the same result as the expression

  Pattern.compile(regex).matcher(str).replaceFirst(repl)

  Note that backslashes (\) and dollar signs ($) in the replacement string may cause the results to be different than if it were being treated as a literal replacement string; seeMatcher.replaceFirst(java.lang.String). UseMatcher.quoteReplacement(java.lang.String) to suppress the special meaning of these characters, if desired.

  Parameters:

  regex - the regular expression to which this string is to be matched

  replacement - the string to be substituted for the first match

  Returns:

  The resultingString

  Throws:

  PatternSyntaxException - if the regular expression's syntax is invalid

  Since:

  1.4

  See Also:

  • Pattern

• replaceAll

  public String replaceAll(String regex,String replacement)

  Replaces each substring of this string that matches the givenregular expression with the given replacement.

  An invocation of this method of the formstr.replaceAll(regex,repl) yields exactly the same result as the expression

  Pattern.compile(regex).matcher(str).replaceAll(repl)

  Note that backslashes (\) and dollar signs ($) in the replacement string may cause the results to be different than if it were being treated as a literal replacement string; seeMatcher.replaceAll. UseMatcher.quoteReplacement(java.lang.String) to suppress the special meaning of these characters, if desired.

  Parameters:

  regex - the regular expression to which this string is to be matched

  replacement - the string to be substituted for each match

  Returns:

  The resultingString

  Throws:

  PatternSyntaxException - if the regular expression's syntax is invalid

  Since:

  1.4

  See Also:

  • Pattern

• replace

  public String replace(CharSequence target,CharSequence replacement)

  Replaces each substring of this string that matches the literal target sequence with the specified literal replacement sequence. The replacement proceeds from the beginning of the string to the end, for example, replacing "aa" with "b" in the string "aaa" will result in "ba" rather than "ab".

  Parameters:

  target - The sequence of char values to be replaced

  replacement - The replacement sequence of char values

  Returns:

  The resulting string

  Since:

  1.5

• split

  public String[] split(String regex, int limit)

  Splits this string around matches of the givenregular expression.

  The array returned by this method contains each substring of this string that is terminated by another substring that matches the given expression or is terminated by the end of the string. The substrings in the array are in the order in which they occur in this string. If the expression does not match any part of the input then the resulting array has just one element, namely this string.

  When there is a positive-width match at the beginning of this string then an empty leading substring is included at the beginning of the resulting array. A zero-width match at the beginning however never produces such empty leading substring.

  Thelimit parameter controls the number of times the pattern is applied and therefore affects the length of the resulting array.

  • If thelimit is positive then the pattern will be applied at mostlimit - 1 times, the array's length will be no greater thanlimit, and the array's last entry will contain all input beyond the last matched delimiter.

  • If thelimit is zero then the pattern will be applied as many times as possible, the array can have any length, and trailing empty strings will be discarded.

  • If thelimit is negative then the pattern will be applied as many times as possible and the array can have any length.

  The string"boo:and:foo", for example, yields the following results with these parameters:

  Split example showing regex, limit, and result

  Regex	Limit	Result
  :	2	{ "boo", "and:foo" }
  	5	{ "boo", "and", "foo" }
  	-2	{ "boo", "and", "foo" }
  o	5	{ "b", "", ":and:f", "", "" }
  	-2	{ "b", "", ":and:f", "", "" }
  	0	{ "b", "", ":and:f" }

  An invocation of this method of the formstr.split(regex, n) yields the same result as the expression

  Pattern.compile(regex).split(str, n)

  Parameters:

  regex - the delimiting regular expression

  limit - the result threshold, as described above

  Returns:

  the array of strings computed by splitting this string around matches of the given regular expression

  Throws:

  PatternSyntaxException - if the regular expression's syntax is invalid

  Since:

  1.4

  See Also:

  • Pattern

• splitWithDelimiters

  public String[] splitWithDelimiters(String regex, int limit)

  Splits this string around matches of the given regular expression and returns both the strings and the matching delimiters.

  The array returned by this method contains each substring of this string that is terminated by another substring that matches the given expression or is terminated by the end of the string. Each substring is immediately followed by the subsequence (the delimiter) that matches the given expression,except for the last substring, which is not followed by anything. The substrings in the array and the delimiters are in the order in which they occur in the input. If the expression does not match any part of the input then the resulting array has just one element, namely this string.

  When there is a positive-width match at the beginning of this string then an empty leading substring is included at the beginning of the resulting array. A zero-width match at the beginning however never produces such empty leading substring nor the empty delimiter.

  Thelimit parameter controls the number of times the pattern is applied and therefore affects the length of the resulting array.

  • If thelimit is positive then the pattern will be applied at mostlimit - 1 times, the array's length will be no greater than 2 ×limit - 1, and the array's last entry will contain all input beyond the last matched delimiter.
  • If thelimit is zero then the pattern will be applied as many times as possible, the array can have any length, and trailing empty strings will be discarded.
  • If thelimit is negative then the pattern will be applied as many times as possible and the array can have any length.

  The input"boo:::and::foo", for example, yields the following results with these parameters:

  Split example showing regex, limit, and result

  Regex	Limit	Result
  :+	2	{ "boo", ":::", "and::foo" }
  	5	{ "boo", ":::", "and", "::", "foo" }
  	-1	{ "boo", ":::", "and", "::", "foo" }
  o	5	{ "b", "o", "", "o", ":::and::f", "o", "", "o", "" }
  	-1	{ "b", "o", "", "o", ":::and::f", "o", "", "o", "" }
  	0	{ "b", "o", "", "o", ":::and::f", "o", "", "o" }

  API Note:

  An invocation of this method of the formstr.splitWithDelimiters(regex, n) yields the same result as the expression

  Pattern.compile(regex).splitWithDelimiters(str, n)

  Parameters:

  regex - the delimiting regular expression

  limit - the result threshold, as described above

  Returns:

  the array of strings computed by splitting this string around matches of the given regular expression, alternating substrings and matching delimiters

  Since:

  21

• split

  public String[] split(String regex)

  Splits this string around matches of the givenregular expression.

  This method works as if by invoking the two-argumentsplit method with the given expression and a limit argument of zero. Trailing empty strings are therefore not included in the resulting array.

  The string"boo:and:foo", for example, yields the following results with these expressions:

  Split examples showing regex and result

  Regex	Result
  :	{ "boo", "and", "foo" }
  o	{ "b", "", ":and:f" }

  Parameters:

  regex - the delimiting regular expression

  Returns:

  the array of strings computed by splitting this string around matches of the given regular expression

  Throws:

  PatternSyntaxException - if the regular expression's syntax is invalid

  Since:

  1.4

  See Also:

  • Pattern

• join

  public static String join(CharSequence delimiter,CharSequence... elements)

  Returns a new String composed of copies of theCharSequence elements joined together with a copy of the specifieddelimiter.

  For example,

       String message = String.join("-", "Java", "is", "cool");     // message returned is: "Java-is-cool"

  Note that if an element is null, then"null" is added.

  Parameters:

  delimiter - the delimiter that separates each element

  elements - the elements to join together.

  Returns:

  a newString that is composed of theelements separated by thedelimiter

  Throws:

  NullPointerException - Ifdelimiter orelements isnull

  Since:

  1.8

  See Also:

  • StringJoiner

• join

  public static String join(CharSequence delimiter,Iterable<? extendsCharSequence> elements)

  Returns a newString composed of copies of theCharSequence elements joined together with a copy of the specifieddelimiter.

  For example,

       List<String> strings = List.of("Java", "is", "cool");     String message = String.join(" ", strings);     // message returned is: "Java is cool"     Set<String> strings =         new LinkedHashSet<>(List.of("Java", "is", "very", "cool"));     String message = String.join("-", strings);     // message returned is: "Java-is-very-cool"

  Note that if an individual element isnull, then"null" is added.

  Parameters:

  delimiter - a sequence of characters that is used to separate each of theelements in the resultingString

  elements - anIterable that will have itselements joined together.

  Returns:

  a newString that is composed from theelements argument

  Throws:

  NullPointerException - Ifdelimiter orelements isnull

  Since:

  1.8

  See Also:

  • join(CharSequence,CharSequence...)
  • StringJoiner

• toLowerCase

  public String toLowerCase(Locale locale)

  Converts all of the characters in thisString to lower case using the rules of the givenLocale. Case mapping is based on the Unicode Standard version specified by theCharacter class. Since case mappings are not always 1:1 char mappings, the resultingString and thisString may differ in length.

  Examples of lowercase mappings are in the following table:

  Lowercase mapping examples showing language code of locale, upper case, lower case, and description

  Language Code of Locale	Upper Case	Lower Case	Description
  tr (Turkish)	\u0130	\u0069	capital letter I with dot above -> small letter i
  tr (Turkish)	\u0049	\u0131	capital letter I -> small letter dotless i
  (all)	French Fries	french fries	lowercased all chars in String
  (all)	ΙΧΘΥΣ	ιχθυσ	lowercased all chars in String

  Parameters:

  locale - use the case transformation rules for this locale

  Returns:

  theString, converted to lowercase.

  Since:

  1.1

  See Also:

  • toLowerCase()
  • toUpperCase()
  • toUpperCase(Locale)

• toLowerCase

  public String toLowerCase()

  Converts all of the characters in thisString to lower case using the rules of the default locale. This method is equivalent totoLowerCase(Locale.getDefault()).

  API Note:

  This method is locale sensitive, and may produce unexpected results if used for strings that are intended to be interpreted locale independently. Examples are programming language identifiers, protocol keys, and HTML tags. For instance,"TITLE".toLowerCase() in a Turkish locale returns"t\u0131tle", where '\u0131' is the LATIN SMALL LETTER DOTLESS I character. To obtain correct results for locale insensitive strings, usetoLowerCase(Locale.ROOT).

  Returns:

  theString, converted to lowercase.

  See Also:

  • toLowerCase(Locale)

• toUpperCase

  public String toUpperCase(Locale locale)

  Converts all of the characters in thisString to upper case using the rules of the givenLocale. Case mapping is based on the Unicode Standard version specified by theCharacter class. Since case mappings are not always 1:1 char mappings, the resultingString and thisString may differ in length.

  Examples of locale-sensitive and 1:M case mappings are in the following table:

  Examples of locale-sensitive and 1:M case mappings. Shows Language code of locale, lower case, upper case, and description.

  Language Code of Locale	Lower Case	Upper Case	Description
  tr (Turkish)	\u0069	\u0130	small letter i -> capital letter I with dot above
  tr (Turkish)	\u0131	\u0049	small letter dotless i -> capital letter I
  (all)	\u00df	\u0053 \u0053	small letter sharp s -> two letters: SS
  (all)	Fahrvergnügen	FAHRVERGNÜGEN

  Parameters:

  locale - use the case transformation rules for this locale

  Returns:

  theString, converted to uppercase.

  Since:

  1.1

  See Also:

  • toUpperCase()
  • toLowerCase()
  • toLowerCase(Locale)

• toUpperCase

  public String toUpperCase()

  Converts all of the characters in thisString to upper case using the rules of the default locale. This method is equivalent totoUpperCase(Locale.getDefault()).

  API Note:

  This method is locale sensitive, and may produce unexpected results if used for strings that are intended to be interpreted locale independently. Examples are programming language identifiers, protocol keys, and HTML tags. For instance,"title".toUpperCase() in a Turkish locale returns"T\u0130TLE", where '\u0130' is the LATIN CAPITAL LETTER I WITH DOT ABOVE character. To obtain correct results for locale insensitive strings, usetoUpperCase(Locale.ROOT).

  Returns:

  theString, converted to uppercase.

  See Also:

  • toUpperCase(Locale)

• trim

  public String trim()

  Returns a string whose value is this string, with all leading and trailing space removed, where space is defined as any character whose codepoint is less than or equal to'U+0020' (the space character).

  If thisString object represents an empty character sequence, or the first and last characters of character sequence represented by thisString object both have codes that are not space (as defined above), then a reference to thisString object is returned.

  Otherwise, if all characters in this string are space (as defined above), then aString object representing an empty string is returned.

  Otherwise, letk be the index of the first character in the string whose code is not a space (as defined above) and letm be the index of the last character in the string whose code is not a space (as defined above). AString object is returned, representing the substring of this string that begins with the character at indexk and ends with the character at indexm-that is, the result ofthis.substring(k, m + 1).

  This method may be used to trim space (as defined above) from the beginning and end of a string.

  Returns:

  a string whose value is this string, with all leading and trailing space removed, or this string if it has no leading or trailing space.

• strip

  public String strip()

  Returns a string whose value is this string, with all leading and trailingwhite space removed.

  If thisString object represents an empty string, or if all code points in this string arewhite space, then an empty string is returned.

  Otherwise, returns a substring of this string beginning with the first code point that is not awhite space up to and including the last code point that is not awhite space.

  This method may be used to stripwhite space from the beginning and end of a string.

  Returns:

  a string whose value is this string, with all leading and trailing white space removed

  Since:

  11

  See Also:

  • Character.isWhitespace(int)

• stripLeading

  public String stripLeading()

  Returns a string whose value is this string, with all leadingwhite space removed.

  If thisString object represents an empty string, or if all code points in this string arewhite space, then an empty string is returned.

  Otherwise, returns a substring of this string beginning with the first code point that is not awhite space up to and including the last code point of this string.

  This method may be used to trimwhite space from the beginning of a string.

  Returns:

  a string whose value is this string, with all leading white space removed

  Since:

  11

  See Also:

  • Character.isWhitespace(int)

• stripTrailing

  public String stripTrailing()

  Returns a string whose value is this string, with all trailingwhite space removed.

  If thisString object represents an empty string, or if all characters in this string arewhite space, then an empty string is returned.

  Otherwise, returns a substring of this string beginning with the first code point of this string up to and including the last code point that is not awhite space.

  This method may be used to trimwhite space from the end of a string.

  Returns:

  a string whose value is this string, with all trailing white space removed

  Since:

  11

  See Also:

  • Character.isWhitespace(int)

• isBlank

  public boolean isBlank()

  Returnstrue if the string is empty or contains onlywhite space codepoints, otherwisefalse.

  Returns:

  true if the string is empty or contains onlywhite space codepoints, otherwisefalse

  Since:

  11

  See Also:

  • Character.isWhitespace(int)

• lines

  public Stream<String> lines()

  Returns a stream of lines extracted from this string, separated by line terminators.

  Aline terminator is one of the following: a line feed character"\n" (U+000A), a carriage return character"\r" (U+000D), or a carriage return followed immediately by a line feed"\r\n" (U+000D U+000A).

  Aline is either a sequence of zero or more characters followed by a line terminator, or it is a sequence of one or more characters followed by the end of the string. A line does not include the line terminator.

  The stream returned by this method contains the lines from this string in the order in which they occur.

  API Note:

  This definition ofline implies that an empty string has zero lines and that there is no empty line following a line terminator at the end of a string.

  Implementation Note:

  This method provides better performance than split("\R") by supplying elements lazily and by faster search of new line terminators.

  Returns:

  the stream of lines extracted from this string

  Since:

  11

• indent

  public String indent(int n)

  Adjusts the indentation of each line of this string based on the value ofn, and normalizes line termination characters.

  This string is conceptually separated into lines usinglines(). Each line is then adjusted as described below and then suffixed with a line feed"\n" (U+000A). The resulting lines are then concatenated and returned.

  Ifn > 0 thenn spaces (U+0020) are inserted at the beginning of each line.

  Ifn < 0 then up tonwhite space characters are removed from the beginning of each line. If a given line does not contain sufficient white space then all leadingwhite space characters are removed. Each white space character is treated as a single character. In particular, the tab character"\t" (U+0009) is considered a single character; it is not expanded.

  Ifn == 0 then the line remains unchanged. However, line terminators are still normalized.

  Parameters:

  n - number of leadingwhite space characters to add or remove

  Returns:

  string with indentation adjusted and line endings normalized

  Since:

  12

  See Also:

  • lines()
  • isBlank()
  • Character.isWhitespace(int)

• stripIndent

  public String stripIndent()

  Returns a string whose value is this string, with incidentalwhite space removed from the beginning and end of every line.

  Incidentalwhite space is often present in a text block to align the content with the opening delimiter. For example, in the following code, dots represent incidentalwhite space:

   String html = """ ..............<html> ..............    <body> ..............        <p>Hello, world</p> ..............    </body> ..............</html> ..............""";

  This method treats the incidentalwhite space as indentation to be stripped, producing a string that preserves the relative indentation of the content. Using | to visualize the start of each line of the string:

   |<html> |    <body> |        <p>Hello, world</p> |    </body> |</html>

  First, the individual lines of this string are extracted. Aline is a sequence of zero or more characters followed by either a line terminator or the end of the string. If the string has at least one line terminator, the last line consists of the characters between the last terminator and the end of the string. Otherwise, if the string has no terminators, the last line is the start of the string to the end of the string, in other words, the entire string. A line does not include the line terminator.

  Then, theminimum indentation (min) is determined as follows:

  • For each non-blank line (as defined byisBlank()), the leadingwhite space characters are counted.

  • The leadingwhite space characters on the last line are also counted even ifblank.

  Themin value is the smallest of these counts.

  For eachnon-blank line,min leadingwhite space characters are removed, and any trailingwhite space characters are removed.Blank lines are replaced with the empty string.

  Finally, the lines are joined into a new string, using the LF character"\n" (U+000A) to separate lines.

  API Note:

  This method's primary purpose is to shift a block of lines as far as possible to the left, while preserving relative indentation. Lines that were indented the least will thus have no leadingwhite space. The result will have the same number of line terminators as this string. If this string ends with a line terminator then the result will end with a line terminator.

  Implementation Requirements:

  This method treats allwhite space characters as having equal width. As long as the indentation on every line is consistently composed of the same character sequences, then the result will be as described above.

  Returns:

  string with incidental indentation removed and line terminators normalized

  Since:

  15

  See Also:

  • lines()
  • isBlank()
  • indent(int)
  • Character.isWhitespace(int)

• translateEscapes

  public String translateEscapes()

  Returns a string whose value is this string, with escape sequences translated as if in a string literal.

  Escape sequences are translated as follows;

  Translation

  Escape	Name	Translation
  \b	backspace	U+0008
  \t	horizontal tab	U+0009
  \n	line feed	U+000A
  \f	form feed	U+000C
  \r	carriage return	U+000D
  \s	space	U+0020
  \"	double quote	U+0022
  \'	single quote	U+0027
  \\	backslash	U+005C
  \0 - \377	octal escape	code point equivalents
  \<line-terminator>	continuation	discard

  Implementation Note:

  This method doesnot translate Unicode escapes such as "\u2022". Unicode escapes are translated by the Java compiler when reading input characters and are not part of the string literal specification.

  Returns:

  String with escape sequences translated.

  Throws:

  IllegalArgumentException - when an escape sequence is malformed.

  SeeJava Language Specification:

  3.10.7 Escape Sequences
  

  Since:

  15

• transform

  public <R> R transform(Function<? superString, ? extends R> f)

  This method allows the application of a function tothis string. The function should expect a single String argument and produce anR result.

  Any exception thrown byf.apply() will be propagated to the caller.

  Type Parameters:

  R - the type of the result

  Parameters:

  f - a function to apply

  Returns:

  the result of applying the function to this string

  Since:

  12

  See Also:

  • Function

• toString

  public String toString()

  This object (which is already a string!) is itself returned.

  Specified by:

  toString in interface CharSequence

  Overrides:

  toString in class Object

  Returns:

  the string itself.

• chars

  public IntStream chars()

  Returns a stream ofint zero-extending thechar values from this sequence. Any char which maps to asurrogate code point is passed through uninterpreted.

  Specified by:

  chars in interface CharSequence

  Returns:

  an IntStream of char values from this sequence

  Since:

  9

• codePoints

  public IntStream codePoints()

  Returns a stream of code point values from this sequence. Any surrogate pairs encountered in the sequence are combined as if byCharacter.toCodePoint and the result is passed to the stream. Any other code units, including ordinary BMP characters, unpaired surrogates, and undefined code units, are zero-extended toint values which are then passed to the stream.

  Specified by:

  codePoints in interface CharSequence

  Returns:

  an IntStream of Unicode code points from this sequence

  Since:

  9

• toCharArray

  public char[] toCharArray()

  Converts this string to a new character array.

  Returns:

  a newly allocated character array whose length is the length of this string and whose contents are initialized to contain the character sequence represented by this string.

• format

  public static String format(String format,Object... args)

  Returns a formatted string using the specified format string and arguments.

  The locale always used is the one returned byLocale.getDefault(Locale.Category) withFORMAT category specified.

  Parameters:

  format - Aformat string

  args - Arguments referenced by the format specifiers in the format string. If there are more arguments than format specifiers, the extra arguments are ignored. The number of arguments is variable and may be zero. The maximum number of arguments is limited by the maximum dimension of a Java array as defined byThe Java Virtual Machine Specification. The behaviour on anull argument depends on theconversion.

  Returns:

  A formatted string

  Throws:

  IllegalFormatException - If a format string contains an illegal syntax, a format specifier that is incompatible with the given arguments, insufficient arguments given the format string, or other illegal conditions. For specification of all possible formatting errors, see theDetails section of the formatter class specification.

  Since:

  1.5

  See Also:

  • Formatter

• format

  public static String format(Locale l,String format,Object... args)

  Returns a formatted string using the specified locale, format string, and arguments.

  Parameters:

  l - Thelocale to apply during formatting. Ifl isnull then no localization is applied.

  format - Aformat string

  args - Arguments referenced by the format specifiers in the format string. If there are more arguments than format specifiers, the extra arguments are ignored. The number of arguments is variable and may be zero. The maximum number of arguments is limited by the maximum dimension of a Java array as defined byThe Java Virtual Machine Specification. The behaviour on anull argument depends on theconversion.

  Returns:

  A formatted string

  Throws:

  IllegalFormatException - If a format string contains an illegal syntax, a format specifier that is incompatible with the given arguments, insufficient arguments given the format string, or other illegal conditions. For specification of all possible formatting errors, see theDetails section of the formatter class specification

  Since:

  1.5

  See Also:

  • Formatter

• formatted

  public String formatted(Object... args)

  Formats using this string as the format string, and the supplied arguments.

  Implementation Requirements:

  This method is equivalent toString.format(this, args).

  Parameters:

  args - Arguments referenced by the format specifiers in this string.

  Returns:

  A formatted string

  Since:

  15

  See Also:

  • format(String,Object...)
  • Formatter

• valueOf

  public static String valueOf(Object obj)

  Returns the string representation of theObject argument.

  Parameters:

  obj - anObject.

  Returns:

  if the argument isnull, then a string equal to"null"; otherwise, the value ofobj.toString() is returned.

  See Also:

  • Object.toString()

• valueOf

  public static String valueOf(char[] data)

  Returns the string representation of thechar array argument. The contents of the character array are copied; subsequent modification of the character array does not affect the returned string.

  The contents of the string are unspecified if the character array is modified during string construction.

  Parameters:

  data - the character array.

  Returns:

  aString that contains the characters of the character array.

• valueOf

  public static String valueOf(char[] data, int offset, int count)

  Returns the string representation of a specific subarray of thechar array argument.

  Theoffset argument is the index of the first character of the subarray. Thecount argument specifies the length of the subarray. The contents of the subarray are copied; subsequent modification of the character array does not affect the returned string.

  The contents of the string are unspecified if the character array is modified during string construction.

  Parameters:

  data - the character array.

  offset - initial offset of the subarray.

  count - length of the subarray.

  Returns:

  aString that contains the characters of the specified subarray of the character array.

  Throws:

  IndexOutOfBoundsException - ifoffset is negative, orcount is negative, oroffset+count is larger thandata.length.

• copyValueOf

  public static String copyValueOf(char[] data, int offset, int count)

  Equivalent tovalueOf(char[], int, int).

  Parameters:

  data - the character array.

  offset - initial offset of the subarray.

  count - length of the subarray.

  Returns:

  aString that contains the characters of the specified subarray of the character array.

  Throws:

  IndexOutOfBoundsException - ifoffset is negative, orcount is negative, oroffset+count is larger thandata.length.

• copyValueOf

  public static String copyValueOf(char[] data)

  Equivalent tovalueOf(char[]).

  Parameters:

  data - the character array.

  Returns:

  aString that contains the characters of the character array.

• valueOf

  public static String valueOf(boolean b)

  Returns the string representation of theboolean argument.

  Parameters:

  b - aboolean.

  Returns:

  if the argument istrue, a string equal to"true" is returned; otherwise, a string equal to"false" is returned.

• valueOf

  public static String valueOf(char c)

  Returns the string representation of thechar argument.

  Parameters:

  c - achar.

  Returns:

  a string of length1 containing as its single character the argumentc.

• valueOf

  public static String valueOf(int i)

  Returns the string representation of theint argument.

  The representation is exactly the one returned by theInteger.toString method of one argument.

  Parameters:

  i - anint.

  Returns:

  a string representation of theint argument.

  See Also:

  • Integer.toString(int, int)

• valueOf

  public static String valueOf(long l)

  Returns the string representation of thelong argument.

  The representation is exactly the one returned by theLong.toString method of one argument.

  Parameters:

  l - along.

  Returns:

  a string representation of thelong argument.

  See Also:

  • Long.toString(long)

• valueOf

  public static String valueOf(float f)

  Returns the string representation of thefloat argument.

  The representation is exactly the one returned by theFloat.toString method of one argument.

  Parameters:

  f - afloat.

  Returns:

  a string representation of thefloat argument.

  See Also:

  • Float.toString(float)

• valueOf

  public static String valueOf(double d)

  Returns the string representation of thedouble argument.

  The representation is exactly the one returned by theDouble.toString method of one argument.

  Parameters:

  d - adouble.

  Returns:

  a string representation of thedouble argument.

  See Also:

  • Double.toString(double)

• intern

  public String intern()

  Returns a canonical representation for the string object.

  A pool of strings, initially empty, is maintained privately by the classString.

  When the intern method is invoked, if the pool already contains a string equal to thisString object as determined by theequals(Object) method, then the string from the pool is returned. Otherwise, thisString object is added to the pool and a reference to thisString object is returned.

  It follows that for any two stringss andt,s.intern() == t.intern() istrue if and only ifs.equals(t) istrue.

  All literal strings and string-valued constant expressions are interned. String literals are defined in section3.10.5 of theThe Java Language Specification.

  Returns:

  a string that has the same contents as this string, but is guaranteed to be from a pool of unique strings.

• repeat

  public String repeat(int count)

  Returns a string whose value is the concatenation of this string repeatedcount times.

  If this string is empty or count is zero then the empty string is returned.

  Parameters:

  count - number of times to repeat

  Returns:

  A string composed of this string repeatedcount times or the empty string if this string is empty or count is zero

  Throws:

  IllegalArgumentException - if thecount is negative.

  Since:

  11

• describeConstable

  public Optional<String> describeConstable()

  Returns anOptional containing the nominal descriptor for this instance, which is the instance itself.

  Specified by:

  describeConstable in interface Constable

  Returns:

  anOptional describing theString instance

  Since:

  12

• resolveConstantDesc

  public String resolveConstantDesc(MethodHandles.Lookup lookup)

  Resolves this instance as aConstantDesc, the result of which is the instance itself.

  Specified by:

  resolveConstantDesc in interface ConstantDesc

  Parameters:

  lookup - ignored

  Returns:

  theString instance

  Since:

  12