Method Summary

Method Details

• equals

  public static boolean equals(Object a,Object b)

  Returnstrue if the arguments are equal to each other andfalse otherwise. Consequently, if both arguments arenull,true is returned. Otherwise, if the first argument is not null, equality is determined by calling theequals method of the first argument with the second argument of this method. Otherwise,false is returned.

  Parameters:

  a - an object

  b - an object to be compared witha for equality

  Returns:

  true if the arguments are equal to each other andfalse otherwise

  See Also:

  • Object.equals(Object)

• deepEquals

  public static boolean deepEquals(Object a,Object b)

  Returnstrue if the arguments are deeply equal to each other andfalse otherwise. Twonull values are deeply equal. If both arguments are arrays, the algorithm inArrays.deepEquals is used to determine equality. Otherwise, equality is determined by using theequals method of the first argument.

  Parameters:

  a - an object

  b - an object to be compared witha for deep equality

  Returns:

  true if the arguments are deeply equal to each other andfalse otherwise

  See Also:

  • Arrays.deepEquals(Object[], Object[])
  • equals(Object, Object)

• hashCode

  public static int hashCode(Object o)

  Returns the hash code of a non-null argument and 0 for anull argument.

  Parameters:

  o - an object

  Returns:

  the hash code of a non-null argument and 0 for anull argument

  See Also:

  • Object.hashCode()

• hash

  public static int hash(Object... values)

  Returns a hash code for a sequence of input values. The hash code is generated as if all the input values were placed into an array, and that array were hashed by callingArrays.hashCode(Object[]).

  This method is useful for implementingObject.hashCode() on objects containing multiple fields. For example, if an object that has three fields,x, y, andz, one could write:

   @Override public int hashCode() {     return Objects.hash(x, y, z); }

  Warning: When a single object reference is supplied, the returned value does not equal the hash code of that object reference. This value can be computed by callinghashCode(Object).

  Parameters:

  values - the values to be hashed

  Returns:

  a hash code for a sequence of input values

  See Also:

  • Arrays.hashCode(Object[])
  • List.hashCode()

• toString

  public static String toString(Object o)

  Returns the result of callingtoString for a non-null argument and"null" for anull argument.

  Parameters:

  o - an object

  Returns:

  the result of callingtoString for a non-null argument and"null" for anull argument

  See Also:

  • Object.toString()
  • String.valueOf(Object)

• toString

  public static String toString(Object o,String nullDefault)

  Returns the result of callingtoString on the first argument if the first argument is notnull and the second argument otherwise.

  Parameters:

  o - an object

  nullDefault - string to return if the first argument isnull

  Returns:

  the result of callingtoString on the first argument if the first argument is notnull and the second argument otherwise

  See Also:

  • toString(Object)

• toIdentityString

  public static String toIdentityString(Object o)

  Returns a string equivalent to the string returned by Object.toString if that method andhashCode are not overridden.

  Implementation Requirements:

  The method returns a string equivalent to:
  o.getClass().getName() + "@" + Integer.toHexString(System.identityHashCode(o))

  Implementation Note:

  This method constructs a string for an object without calling any overridable methods of the object.

  Parameters:

  o - an object

  Returns:

  a string equivalent to the string returned by Object.toString if that method andhashCode are not overridden

  Throws:

  NullPointerException - if the argument is null

  Since:

  19

  See Also:

  • Object.toString()
  • System.identityHashCode(Object)

• compare

  public static <T> int compare(T a, T b,Comparator<? super T> c)

  Returns 0 if the arguments are identical and c.compare(a, b) otherwise. Consequently, if both arguments arenull 0 is returned.

  Note that if one of the arguments isnull, a NullPointerException may or may not be thrown depending on what ordering policy, if any, theComparator chooses to have fornull values.

  Type Parameters:

  T - the type of the objects being compared

  Parameters:

  a - an object

  b - an object to be compared witha

  c - theComparator to compare the first two arguments

  Returns:

  0 if the arguments are identical and c.compare(a, b) otherwise

  See Also:

  • Comparable
  • Comparator

• requireNonNull

  public static <T> T requireNonNull(T obj)

  Checks that the specified object reference is notnull. This method is designed primarily for doing parameter validation in methods and constructors, as demonstrated below:

   public Foo(Bar bar) {     this.bar = Objects.requireNonNull(bar); }

  Type Parameters:

  T - the type of the reference

  Parameters:

  obj - the object reference to check for nullity

  Returns:

  obj if notnull

  Throws:

  NullPointerException - ifobj isnull

• requireNonNull

  public static <T> T requireNonNull(T obj,String message)

  Checks that the specified object reference is notnull and throws a customizedNullPointerException if it is. This method is designed primarily for doing parameter validation in methods and constructors with multiple parameters, as demonstrated below:

   public Foo(Bar bar, Baz baz) {     this.bar = Objects.requireNonNull(bar, "bar must not be null");     this.baz = Objects.requireNonNull(baz, "baz must not be null"); }

  Type Parameters:

  T - the type of the reference

  Parameters:

  obj - the object reference to check for nullity

  message - detail message to be used in the event that a NullPointerException is thrown

  Returns:

  obj if notnull

  Throws:

  NullPointerException - ifobj isnull

• isNull

  public static boolean isNull(Object obj)

  Returnstrue if the provided reference is null;false otherwise.

  API Note:

  This method exists to be used as aPredicate,filter(Objects::isNull)

  Parameters:

  obj - a reference to be checked againstnull

  Returns:

  true if the provided reference is null;false otherwise

  Since:

  1.8

  See Also:

  • Predicate

• nonNull

  public static boolean nonNull(Object obj)

  Returnstrue if the provided reference is non-null;false otherwise.

  API Note:

  This method exists to be used as aPredicate,filter(Objects::nonNull)

  Parameters:

  obj - a reference to be checked againstnull

  Returns:

  true if the provided reference is non-null;false otherwise

  Since:

  1.8

  See Also:

  • Predicate

• requireNonNullElse

  public static <T> T requireNonNullElse(T obj, T defaultObj)

  Returns the first argument if it is non-null and otherwise the second argument if it is non-null.

  Type Parameters:

  T - the type of the reference

  Parameters:

  obj - an object

  defaultObj - a non-null object to return if the first argument isnull

  Returns:

  the first argument if it is non-null and otherwise the second argument if it is non-null

  Throws:

  NullPointerException - if bothobj is null anddefaultObj isnull

  Since:

  9

• requireNonNullElseGet

  public static <T> T requireNonNullElseGet(T obj,Supplier<? extends T> supplier)

  Returns the first argument if it is non-null and otherwise the value fromsupplier.get() if it is non-null.

  Type Parameters:

  T - the type of the first argument and return type

  Parameters:

  obj - an object

  supplier - of a non-null object to return if the first argument isnull

  Returns:

  the first argument if it is non-null and otherwise the value fromsupplier.get() if it is non-null

  Throws:

  NullPointerException - if bothobj is null and either thesupplier isnull or thesupplier.get() value isnull

  Since:

  9

• requireNonNull

  public static <T> T requireNonNull(T obj,Supplier<String> messageSupplier)

  Checks that the specified object reference is notnull and throws a customizedNullPointerException if it is.

  Unlike the methodrequireNonNull(Object, String), this method allows creation of the message to be deferred until after the null check is made. While this may confer a performance advantage in the non-null case, when deciding to call this method care should be taken that the costs of creating the message supplier are less than the cost of just creating the string message directly.

  Type Parameters:

  T - the type of the reference

  Parameters:

  obj - the object reference to check for nullity

  messageSupplier - supplier of the detail message to be used in the event that aNullPointerException is thrown

  Returns:

  obj if notnull

  Throws:

  NullPointerException - ifobj isnull

  Since:

  1.8

• checkIndex

  public static int checkIndex(int index, int length)

  Checks if theindex is within the bounds of the range from0 (inclusive) tolength (exclusive).

  Theindex is defined to be out of bounds if any of the following inequalities is true:

  • index < 0
  • index >= length
  • length < 0, which is implied from the former inequalities

  Parameters:

  index - the index

  length - the upper-bound (exclusive) of the range

  Returns:

  index if it is within bounds of the range

  Throws:

  IndexOutOfBoundsException - if theindex is out of bounds

  Since:

  9

• checkFromToIndex

  public static int checkFromToIndex(int fromIndex, int toIndex, int length)

  Checks if the sub-range fromfromIndex (inclusive) totoIndex (exclusive) is within the bounds of range from0 (inclusive) tolength (exclusive).

  The sub-range is defined to be out of bounds if any of the following inequalities is true:

  • fromIndex < 0
  • fromIndex > toIndex
  • toIndex > length
  • length < 0, which is implied from the former inequalities

  Parameters:

  fromIndex - the lower-bound (inclusive) of the sub-range

  toIndex - the upper-bound (exclusive) of the sub-range

  length - the upper-bound (exclusive) the range

  Returns:

  fromIndex if the sub-range within bounds of the range

  Throws:

  IndexOutOfBoundsException - if the sub-range is out of bounds

  Since:

  9

• checkFromIndexSize

  public static int checkFromIndexSize(int fromIndex, int size, int length)

  Checks if the sub-range fromfromIndex (inclusive) tofromIndex + size (exclusive) is within the bounds of range from0 (inclusive) tolength (exclusive).

  The sub-range is defined to be out of bounds if any of the following inequalities is true:

  • fromIndex < 0
  • size < 0
  • fromIndex + size > length, taking into account integer overflow
  • length < 0, which is implied from the former inequalities

  Parameters:

  fromIndex - the lower-bound (inclusive) of the sub-interval

  size - the size of the sub-range

  length - the upper-bound (exclusive) of the range

  Returns:

  fromIndex if the sub-range within bounds of the range

  Throws:

  IndexOutOfBoundsException - if the sub-range is out of bounds

  Since:

  9

• checkIndex

  public static long checkIndex(long index, long length)

  Checks if theindex is within the bounds of the range from0 (inclusive) tolength (exclusive).

  Theindex is defined to be out of bounds if any of the following inequalities is true:

  • index < 0
  • index >= length
  • length < 0, which is implied from the former inequalities

  Parameters:

  index - the index

  length - the upper-bound (exclusive) of the range

  Returns:

  index if it is within bounds of the range

  Throws:

  IndexOutOfBoundsException - if theindex is out of bounds

  Since:

  16

• checkFromToIndex

  public static long checkFromToIndex(long fromIndex, long toIndex, long length)

  Checks if the sub-range fromfromIndex (inclusive) totoIndex (exclusive) is within the bounds of range from0 (inclusive) tolength (exclusive).

  The sub-range is defined to be out of bounds if any of the following inequalities is true:

  • fromIndex < 0
  • fromIndex > toIndex
  • toIndex > length
  • length < 0, which is implied from the former inequalities

  Parameters:

  fromIndex - the lower-bound (inclusive) of the sub-range

  toIndex - the upper-bound (exclusive) of the sub-range

  length - the upper-bound (exclusive) the range

  Returns:

  fromIndex if the sub-range within bounds of the range

  Throws:

  IndexOutOfBoundsException - if the sub-range is out of bounds

  Since:

  16

• checkFromIndexSize

  public static long checkFromIndexSize(long fromIndex, long size, long length)

  Checks if the sub-range fromfromIndex (inclusive) tofromIndex + size (exclusive) is within the bounds of range from0 (inclusive) tolength (exclusive).

  The sub-range is defined to be out of bounds if any of the following inequalities is true:

  • fromIndex < 0
  • size < 0
  • fromIndex + size > length, taking into account integer overflow
  • length < 0, which is implied from the former inequalities

  Parameters:

  fromIndex - the lower-bound (inclusive) of the sub-interval

  size - the size of the sub-range

  length - the upper-bound (exclusive) of the range

  Returns:

  fromIndex if the sub-range within bounds of the range

  Throws:

  IndexOutOfBoundsException - if the sub-range is out of bounds

  Since:

  16