com.google.common.base
Class Objects

java.lang.Object
  com.google.common.base.Objects

public final class Objects
extends Object

Helper functions that can operate on any Object.

Since:

2 (imported from Google Collections Library)

Author:

Laurence Gonsalves

Nested Class Summary

static class

Objects.ToStringHelper Support class for toStringHelper(java.lang.Object).

Method Summary

static boolean	equal(Object a, Object b) Determines whether two possibly-null objects are equal.
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 int	hashCode(Object... objects) Generates a hash code for multiple values.
static Objects.ToStringHelper	toStringHelper(Object object) Creates an instance of Objects.ToStringHelper.

Methods inherited from class java.lang.Object

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

Method Detail

equal

public static boolean equal(@Nullable
                            Object a,
                            @Nullable
                            Object b)

Determines whether two possibly-null objects are equal. Returns:

• true if a and b are both null.
• true if a and b are both non-null and they are equal according to Object.equals(Object).
• false in all other situations.

This assumes that any non-null objects passed to this function conform to the equals() contract.

hashCode

public static int hashCode(Object... objects)

Generates a hash code for multiple values. The hash code is generated by calling Arrays.hashCode(Object[]).

This is useful for implementing Object.hashCode(). For example, in an object that has three properties, x, y, and z, one could write:

 public int hashCode() {
   return Objects.hashCode(getX(), getY(), getZ());
 }

Warning: When a single object is supplied, the returned hash code does not equal the hash code of that object.

toStringHelper

@Beta
public static Objects.ToStringHelper toStringHelper(Object object)

Creates an instance of Objects.ToStringHelper.

This is helpful for implementing Object.toString(). For example, in an object that contains two member variables, x, and y, one could write:

   
   public class ClassName {
     public String toString() {
       return Objects.toStringHelper(this)
           .add("x", x)
           .add("y", y)
           .toString();
     }
   }
 

Assuming the values of x and y are 1 and 2, this code snippet returns the string "ClassName{x=1, y=2}".

Since:

2

firstNonNull

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

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

Returns:

first if first is not null, or second if first is null and second is not null

Throws:

NullPointerException - if both first and second were null

Since:

3