ObjectsCompat

public class ObjectsCompat
extends Object

java.lang.Object
   ↳ androidx.core.util.ObjectsCompat


This class consists of static utility methods for operating on objects.

Summary

Public methods

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 <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)

Checks that the specified object reference is not null.

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

Public methods

equals

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 and if exactly one argument is null, false is returned. 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 equality

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

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 calling Arrays.hashCode(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 ObjectsCompat.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(Object).

Parameters
values Object: the values to be hashed

Returns
int a hash value of the sequence of input values

hashCode

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:

requireNonNull

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

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

toString

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.