ObjectsCompat

Added in 1.1.0

Kotlin |Java

public class ObjectsCompat

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

Summary

Public methods
`static boolean`	`equals(@Nullable Object a, @Nullable Object b)` Returns `true` if the arguments are equal to each other and `false` otherwise.
`static int`	`hash(@Nullable Object[] values)` Generates a hash code for a sequence of input values.
`static int`	`hashCode(@Nullable Object o)` Returns the hash code of a non-`null` argument and 0 for a `null` argument.
`static @NonNull T`	`<T> requireNonNull(@Nullable T obj)` Checks that the specified object reference is not `null`.
`static @NonNull T`	`<T> requireNonNull(@Nullable T obj, @NonNull String message)` Checks that the specified object reference is not `null` and throws a customized `NullPointerException` if it is.
`static @Nullable String`	`toString(@Nullable Object o, @Nullable 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.

Public methods

equals

Added in 1.1.0

public static boolean equals(@Nullable Object a, @Nullable 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
`@Nullable Object a`	an object
`@Nullable Object b`	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
`equals`

hash

public static int hash(@Nullable 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 hashCode.

This method is useful for implementing 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.

Parameters
`@Nullable Object[] values`	the values to be hashed

Returns
`int`	a hash value of the sequence of input values

See also
`hashCode`

hashCode

Added in 1.1.0

public static int hashCode(@Nullable Object o)

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

Parameters
`@Nullable Object o`	an object

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

See also
`hashCode`

requireNonNull

Added in 1.6.0

public static @NonNull T <T> requireNonNull(@Nullable 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
`<T>`	the type of the reference
`@Nullable T obj`	the object reference to check for nullity

Returns
`@NonNull T`	`obj` if not `null`

Throws
`java.lang.NullPointerException`	if `obj` is `null`

requireNonNull

Added in 1.6.0

public static @NonNull T <T> requireNonNull(@Nullable T obj, @NonNull 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
`<T>`	the type of the reference
`@Nullable T obj`	the object reference to check for nullity
`@NonNull String message`	detail message to be used in the event that a `NullPointerException` is thrown

Returns
`@NonNull T`	`obj` if not `null`

Throws
`java.lang.NullPointerException`	if `obj` is `null`

toString

Added in 1.5.0

public static @Nullable String toString(@Nullable Object o, @Nullable 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
`@Nullable Object o`	an object
`@Nullable String nullDefault`	string to return if the first argument is `null`

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