com.google.common.base

Class MoreObjects

java.lang.Object

com.google.common.base.MoreObjects

@GwtCompatible
public final class MoreObjects
extends Object

Helper functions that operate on any Object, and are not already provided in Objects.

See the Guava User Guide on writing Object methods with MoreObjects.

Since:

18.0 (since 2.0 as Objects)

Author:

Laurence Gonsalves

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	MoreObjects.ToStringHelper Support class for toStringHelper(java.lang.Object).

Method Summary

Modifier and Type	Method and Description
static <T> T	firstNonNull(T first, T second) Returns the first of two given parameters that is not null, if either is, or otherwise throws a NullPointerException.
static MoreObjects.ToStringHelper	toStringHelper(Class<?> clazz) Creates an instance of MoreObjects.ToStringHelper in the same manner as toStringHelper(Object), but using the simple name of clazz instead of using an instance's Object.getClass().
static MoreObjects.ToStringHelper	toStringHelper(Object self) Creates an instance of MoreObjects.ToStringHelper.
static MoreObjects.ToStringHelper	toStringHelper(String className) Creates an instance of MoreObjects.ToStringHelper in the same manner as toStringHelper(Object), but using className instead of using an instance's Object.getClass().

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

firstNonNull

public static <T> T firstNonNull(@NullableDecl
                                 T first,
                                 @NullableDecl
                                 T second)

Returns the first of two given parameters that is not null, if either is, or otherwise throws a NullPointerException.

To find the first non-null element in an iterable, use Iterables.find(iterable, Predicates.notNull()). For varargs, use Iterables.find(Arrays.asList(a, b, c, ...), Predicates.notNull()), static importing as necessary.

Note: if first is represented as an Optional, this can be accomplished with first.or(second). That approach also allows for lazy evaluation of the fallback instance, using first.or(supplier).

Java 9 users: use java.util.Objects.requireNonNullElse(first, second) instead.

Returns:

first if it is non-null; otherwise second if it is non-null

Throws:

NullPointerException - if both first and second are null

Since:

18.0 (since 3.0 as Objects.firstNonNull()).

toStringHelper

public static MoreObjects.ToStringHelper toStringHelper(Object self)

Creates an instance of MoreObjects.ToStringHelper.

This is helpful for implementing Object.toString(). Specification by example:

 // Returns "ClassName{}"
 MoreObjects.toStringHelper(this)
     .toString();

 // Returns "ClassName{x=1}"
 MoreObjects.toStringHelper(this)
     .add("x", 1)
     .toString();

 // Returns "MyObject{x=1}"
 MoreObjects.toStringHelper("MyObject")
     .add("x", 1)
     .toString();

 // Returns "ClassName{x=1, y=foo}"
 MoreObjects.toStringHelper(this)
     .add("x", 1)
     .add("y", "foo")
     .toString();

 // Returns "ClassName{x=1}"
 MoreObjects.toStringHelper(this)
     .omitNullValues()
     .add("x", 1)
     .add("y", null)
     .toString();
 

Note that in GWT, class names are often obfuscated.

Parameters:

self - the object to generate the string for (typically this), used only for its class name

Since:

18.0 (since 2.0 as Objects.toStringHelper()).

toStringHelper

public static MoreObjects.ToStringHelper toStringHelper(Class<?> clazz)

Creates an instance of MoreObjects.ToStringHelper in the same manner as toStringHelper(Object), but using the simple name of clazz instead of using an instance's Object.getClass().

Note that in GWT, class names are often obfuscated.

Parameters:

clazz - the Class of the instance

Since:

18.0 (since 7.0 as Objects.toStringHelper()).

toStringHelper

public static MoreObjects.ToStringHelper toStringHelper(String className)

Creates an instance of MoreObjects.ToStringHelper in the same manner as toStringHelper(Object), but using className instead of using an instance's Object.getClass().

Parameters:

className - the name of the instance type

Since:

18.0 (since 7.0 as Objects.toStringHelper()).