Movatterモバイル変換

Class Objects

java.lang.Object
- java.util.Objects

```
public final classObjectsextendsObject
```
This class consists ofstatic utility methods for operating on objects, or checking certain conditions before operation. These utilities includenull-safe ornull-tolerant methods for computing the hash code of an object, returning a string for an object, comparing two objects, and checking if indexes or sub-range values are out of bounds.
API Note:
Static methods such ascheckIndex(int, int),checkFromToIndex(int, int, int), andcheckFromIndexSize(int, int, int) are provided for the convenience of checking if values corresponding to indexes and sub-ranges are out of bounds. Variations of these static methods support customization of the runtime exception, and corresponding exception detail message, that is thrown when values are out of bounds. Such methods accept a functional interface argument, instances ofBiFunction, that maps out-of-bound values to a runtime exception. Care should be taken when using such methods in combination with an argument that is a lambda expression, method reference or class that capture values. In such cases the cost of capture, related to functional interface allocation, may exceed the cost of checking bounds.
Since:
1.7

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method	Description
`static int`	`checkFromIndexSize(int fromIndex, int size, int length)`	Checks if the sub-range from`fromIndex` (inclusive) to`fromIndex + size` (exclusive) is within the bounds of range from`0` (inclusive) to`length` (exclusive).
`static int`	`checkFromToIndex(int fromIndex, int toIndex, int length)`	Checks if the sub-range from`fromIndex` (inclusive) to`toIndex` (exclusive) is within the bounds of range from`0` (inclusive) to`length` (exclusive).
`static int`	`checkIndex(int index, int length)`	Checks if the`index` is within the bounds of the range from`0` (inclusive) to`length` (exclusive).
`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.
`static boolean`	`deepEquals(Object a,Object b)`	Returns`true` if the arguments are deeply equal to each other and`false` otherwise.
`static boolean`	`equals(Object a,Object b)`	Returns`true` if the arguments are equal to each other and`false` otherwise.
`static int`	`hash(Object... values)`	Generates a hash code for a sequence of input values.
`static int`	`hashCode(Object o)`	Returns the hash code of a non-`null` argument and 0 for a`null` argument.
`static boolean`	`isNull(Object obj)`	Returns`true` if the provided reference is`null` otherwise returns`false`.
`static boolean`	`nonNull(Object obj)`	Returns`true` if the provided reference is non-`null` otherwise returns`false`.
`static <T> T`	`requireNonNull(T obj)`	Checks that the specified object reference is not`null`.
`static <T> T`	`requireNonNull(T obj,String message)`	Checks that the specified object reference is not`null` and throws a customized`NullPointerException` if it is.
`static <T> T`	`requireNonNull(T obj,Supplier<String> messageSupplier)`	Checks that the specified object reference is not`null` and throws a customized`NullPointerException` if it is.
`static <T> T`	`requireNonNullElse(T obj, T defaultObj)`	Returns the first argument if it is non-`null` and otherwise returns the non-`null` second argument.
`static <T> T`	`requireNonNullElseGet(T obj,Supplier<? extends T> supplier)`	Returns the first argument if it is non-`null` and otherwise returns the non-`null` value of`supplier.get()`.
`staticString`	`toString(Object o)`	Returns the result of calling`toString` for a non- `null` argument and`"null"` for a`null` argument.
`staticString`	`toString(Object o,String nullDefault)`	Returns the result of calling`toString` on the first argument if the first argument is not`null` and returns the second argument otherwise.

Methods declared in class java.lang.Object
clone,equals,finalize,getClass,hashCode,notify,notifyAll,toString,wait,wait,wait

- Method Detail
  - 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 and if exactly one argument isnull, false is returned. Otherwise, equality is determined by using theequals method of the first argument.
    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)
```
    Generates 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 value of the 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 returns 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 it is notnull and the second argument otherwise.
    See Also:
    toString(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 isnull otherwise returnsfalse.
    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 isnull otherwisefalse
    Since:
    1.8
    See Also:
    Predicate
  - nonNull
```
public static boolean nonNull(Object obj)
```
    Returnstrue if the provided reference is non-null otherwise returnsfalse.
    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 otherwisefalse
    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 returns the non-null second argument.
    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 returns the non-null value ofsupplier.get().
    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

Movatterモバイル変換

Class Objects

Method Summary

Methods declared in class java.lang.Object

Method Detail

equals

deepEquals

hashCode

hash

toString

toString

compare

requireNonNull

requireNonNull

isNull

nonNull

requireNonNullElse

requireNonNullElseGet

requireNonNull

checkIndex

checkFromToIndex

checkFromIndexSize