This threadsafe class holds an int value. It extends java.lang.Number, but unlike the Integer class, it is mutable. Access the int value with the get( ) method and the various methods inherited from Number. You can set the value with the set( ) method or through various atomic methods. In addition to the basic compareAndSet( ) and weakCompareAndSet( ) methods, this class defines methods for atomic pre-increment, post-increment, pre-decrement and post-decrement operations as well as generalized addAndGet( ) and getAndAdd( ) methods. addAndGet( ) atomically adds the specified amount to the stored value and returns the new value. getAndAdd( ) atomically returns the current value and then adds the specified amount to it.

Figure 16-98. java.util.concurrent.atomic.AtomicInteger

public class AtomicInteger extends Number implements Serializable {
// Public Constructors
     public AtomicInteger( );  
     public AtomicInteger(int initialValue);  
// Public Instance Methods
     public final int addAndGet(int delta);  
     public final boolean compareAndSet(int expect, int update);  
     public final int decrementAndGet( );  
     public final int get( );  
     public final int getAndAdd(int delta);  
     public final int getAndDecrement( );                                 default:0
     public final int getAndIncrement( );                                 default:-1
     public final int getAndSet(int newValue);  
     public final int incrementAndGet( );  
     public final void set(int newValue);  
     public final boolean weakCompareAndSet(int expect, int update);  
// Public Methods Overriding Number
     public double doubleValue( );  
     public float floatValue( );  
     public int intValue( );  
     public long longValue( );  
// Public Methods Overriding Object
     public String toString( );  
}