Added in API level 19

Summary: Methods | Inherited Methods

Objects

public final class Objects
extends Object

java.lang.Object
↳	java.util.Objects

---

This class consists of static utility methods for operating on objects, or checking certain conditions before operation. These utilities include null-safe or null-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.

Summary

Public methods
static long	checkFromIndexSize(long fromIndex, long size, long 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	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 long	checkFromToIndex(long fromIndex, long toIndex, long 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 long	checkIndex(long index, long length) Checks if the index is within the bounds of the 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, 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	requireNonNull(T obj) Checks that the specified object reference is not null.
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().
static String	toIdentityString(Object o)
static String	toString(Object o) Returns the result of calling toString for a non-null argument and "null" for a null argument.
static String	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.

Inherited methods

From class java.lang.Object Object clone() Creates and returns a copy of this object. boolean equals(Object obj) Indicates whether some other object is "equal to" this one. void finalize() Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. final Class<?> getClass() Returns the runtime class of this Object. int hashCode() Returns a hash code value for the object. final void notify() Wakes up a single thread that is waiting on this object's monitor. final void notifyAll() Wakes up all threads that are waiting on this object's monitor. String toString() Returns a string representation of the object. final void wait(long timeoutMillis, int nanos) Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed. final void wait(long timeoutMillis) Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed. final void wait() Causes the current thread to wait until it is awakened, typically by being notified or interrupted.

Public methods

checkFromIndexSize

Added in API level 34

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

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	long: the lower-bound (inclusive) of the sub-interval
size	long: the size of the sub-range
length	long: the upper-bound (exclusive) of the range

Returns
long	fromIndex if the sub-range within bounds of the range

Throws
IndexOutOfBoundsException	if the sub-range is out of bounds

checkFromIndexSize

Added in API level 30

public 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).

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	int: the lower-bound (inclusive) of the sub-interval
size	int: the size of the sub-range
length	int: the upper-bound (exclusive) of the range

Returns
int	fromIndex if the sub-range within bounds of the range

Throws
IndexOutOfBoundsException	if the sub-range is out of bounds

checkFromToIndex

Added in API level 30

public 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).

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	int: the lower-bound (inclusive) of the sub-range
toIndex	int: the upper-bound (exclusive) of the sub-range
length	int: the upper-bound (exclusive) the range

Returns
int	fromIndex if the sub-range within bounds of the range

Throws
IndexOutOfBoundsException	if the sub-range is out of bounds

checkFromToIndex

Added in API level 34

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

Checks if the sub-range from fromIndex (inclusive) to toIndex (exclusive) is within the bounds of range from 0 (inclusive) to length (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	long: the lower-bound (inclusive) of the sub-range
toIndex	long: the upper-bound (exclusive) of the sub-range
length	long: the upper-bound (exclusive) the range

Returns
long	fromIndex if the sub-range within bounds of the range

Throws
IndexOutOfBoundsException	if the sub-range is out of bounds

checkIndex

Added in API level 34

public static long checkIndex (long index, 
                long length)

Checks if the index is within the bounds of the range from 0 (inclusive) to length (exclusive).

The index 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	long: the index
length	long: the upper-bound (exclusive) of the range

Returns
long	index if it is within bounds of the range

Throws
IndexOutOfBoundsException	if the index is out of bounds

checkIndex

Added in API level 30

public static int checkIndex (int index, 
                int length)

Checks if the index is within the bounds of the range from 0 (inclusive) to length (exclusive).

The index 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	int: the index
length	int: the upper-bound (exclusive) of the range

Returns
int	index if it is within bounds of the range

Throws
IndexOutOfBoundsException	if the index is out of bounds

compare

Added in API level 19

public static 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 are null 0 is returned.

Note that if one of the arguments is null, a NullPointerException may or may not be thrown depending on what ordering policy, if any, the Comparator chooses to have for null values.

Parameters
a	T: an object
b	T: an object to be compared with a
c	Comparator: the Comparator to compare the first two arguments

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

See also:

• Comparable
• Comparator

deepEquals

Added in API level 19

public static boolean deepEquals (Object a, 
                Object b)

Returns true if the arguments are deeply equal to each other and false otherwise. Two null values are deeply equal. If both arguments are arrays, the algorithm in Arrays.deepEquals is used to determine equality. Otherwise, equality is determined by using the equals method of the first argument.

Parameters
a	Object: an object
b	Object: an object to be compared with a for deep equality

Returns
boolean	true if the arguments are deeply equal to each other and false otherwise

See also:

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

equals

Added in API level 19

public static boolean equals (Object a, 
                Object b)

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

Parameters
a	Object: an object
b	Object: an object to be compared with a for equality

Returns
boolean	true if the arguments are equal to each other and false otherwise

See also:

• Object.equals(Object)

hash

Added in API level 19

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 calling Arrays.hashCode(java.lang.Object[]).

This method is useful for implementing Object.hashCode() on objects containing multiple fields. For example, if an object that has three fields, x, y, and z, 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 calling hashCode(java.lang.Object).

Parameters
values	Object: the values to be hashed

Returns
int	a hash value of the sequence of input values

See also:

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

hashCode

Added in API level 19

public static int hashCode (Object o)

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

Parameters
o	Object: an object

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

See also:

• Object.hashCode()

isNull

Added in API level 24

public static boolean isNull (Object obj)

Returns true if the provided reference is null otherwise returns false.

API Note:

• This method exists to be used as a Predicate, filter(Objects::isNull)

Parameters
obj	Object: a reference to be checked against null

Returns
boolean	true if the provided reference is null otherwise false

See also:

• Predicate

nonNull

Added in API level 24

public static boolean nonNull (Object obj)

Returns true if the provided reference is non-null otherwise returns false.

API Note:

• This method exists to be used as a Predicate, filter(Objects::nonNull)

Parameters
obj	Object: a reference to be checked against null

Returns
boolean	true if the provided reference is non-null otherwise false

See also:

• Predicate

requireNonNull

Added in API level 19

public static T requireNonNull (T obj, 
                String message)

Checks that the specified object reference is not null and throws a customized NullPointerException 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");
 }
 

Parameters
obj	T: the object reference to check for nullity
message	String: detail message to be used in the event that a NullPointerException is thrown

Returns
T	obj if not null

Throws
NullPointerException	if obj is null

requireNonNull

Added in API level 24

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

Checks that the specified object reference is not null and throws a customized NullPointerException if it is.

Unlike the method requireNonNull(java.lang.Object, java.lang.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.

Parameters
obj	T: the object reference to check for nullity
messageSupplier	Supplier: supplier of the detail message to be used in the event that a NullPointerException is thrown

Returns
T	obj if not null

Throws
NullPointerException	if obj is null

requireNonNull

Added in API level 19

public static T requireNonNull (T obj)

Checks that the specified object reference is not null. 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);
 }
 

Parameters
obj	T: the object reference to check for nullity

Returns
T	obj if not null

Throws
NullPointerException	if obj is null

requireNonNullElse

Added in API level 30

public static T requireNonNullElse (T obj, 
                T defaultObj)

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

Parameters
obj	T: an object
defaultObj	T: a non-null object to return if the first argument is null

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

Throws
NullPointerException	if both obj is null and defaultObj is null

requireNonNullElseGet

Added in API level 30

public static 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().

Parameters
obj	T: an object
supplier	Supplier: of a non-null object to return if the first argument is null

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

Throws
NullPointerException	if both obj is null and either the supplier is null or the supplier.get() value is null

toIdentityString

Added in API level 36

public static String toIdentityString (Object o)

Implementation Note:

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

Implementation Requirements:

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

Parameters
o	Object: an object

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

Throws
NullPointerException	if the argument is null

See also:

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

toString

Added in API level 19

public static String toString (Object o)

Returns the result of calling toString for a non-null argument and "null" for a null argument.

Parameters
o	Object: an object

Returns
String	the result of calling toString for a non-null argument and "null" for a null argument

See also:

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

toString

Added in API level 19

public static String 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.

Parameters
o	Object: an object
nullDefault	String: string to return if the first argument is null

Returns
String	the result of calling toString on the first argument if it is not null and the second argument otherwise.

See also:

• toString(Object)