实现一个原子的正整数类：AtomicPositiveInteger详解编程语言

import java.util.concurrent.atomic.AtomicInteger; 
public class AtomicPositiveInteger extends Number { 
private static final long serialVersionUID = -3038533876489105940L; 
private final AtomicInteger i; 
public AtomicPositiveInteger() { 
i = new AtomicInteger(); 
} 
public AtomicPositiveInteger(int initialValue) { 
i = new AtomicInteger(initialValue); 
} 
public final int getAndIncrement() { 
for (;;) { 
int current = i.get(); 
int next = (current >= Integer.MAX_VALUE ? 0 : current + 1); 
if (i.compareAndSet(current, next)) { 
return current; 
} 
} 
} 
public final int getAndDecrement() { 
for (;;) { 
int current = i.get(); 
int next = (current <= 0 ? Integer.MAX_VALUE : current - 1); 
if (i.compareAndSet(current, next)) { 
return current; 
} 
} 
} 
public final int incrementAndGet() { 
for (;;) { 
int current = i.get(); 
int next = (current >= Integer.MAX_VALUE ? 0 : current + 1); 
if (i.compareAndSet(current, next)) { 
return next; 
} 
} 
} 
public final int decrementAndGet() { 
for (;;) { 
int current = i.get(); 
int next = (current <= 0 ? Integer.MAX_VALUE : current - 1); 
if (i.compareAndSet(current, next)) { 
return next; 
} 
} 
} 
public final int get() { 
return i.get(); 
} 
public final void set(int newValue) { 
if (newValue < 0) { 
throw new IllegalArgumentException("new value " + newValue + " < 0"); 
} 
i.set(newValue); 
} 
public final int getAndSet(int newValue) { 
if (newValue < 0) { 
throw new IllegalArgumentException("new value " + newValue + " < 0"); 
} 
return i.getAndSet(newValue); 
} 
public final int getAndAdd(int delta) { 
if (delta < 0) { 
throw new IllegalArgumentException("delta " + delta + " < 0"); 
} 
for (;;) { 
int current = i.get(); 
int next = (current >= Integer.MAX_VALUE - delta + 1 ? delta - 1 : current + delta); 
if (i.compareAndSet(current, next)) { 
return current; 
} 
} 
} 
public final int addAndGet(int delta) { 
if (delta < 0) { 
throw new IllegalArgumentException("delta " + delta + " < 0"); 
} 
for (;;) { 
int current = i.get(); 
int next = (current >= Integer.MAX_VALUE - delta + 1 ? delta - 1 : current + delta); 
if (i.compareAndSet(current, next)) { 
return next; 
} 
} 
} 
public final boolean compareAndSet(int expect, int update) { 
if (update < 0) { 
throw new IllegalArgumentException("update value " + update + " < 0"); 
} 
return i.compareAndSet(expect, update); 
} 
public final boolean weakCompareAndSet(int expect, int update) { 
if (update < 0) { 
throw new IllegalArgumentException("update value " + update + " < 0"); 
} 
return i.weakCompareAndSet(expect, update); 
} 
public byte byteValue() { 
return i.byteValue(); 
} 
public short shortValue() { 
return i.shortValue(); 
} 
public int intValue() { 
return i.intValue(); 
} 
public long longValue() { 
return i.longValue(); 
} 
public float floatValue() { 
return i.floatValue(); 
} 
public double doubleValue() { 
return i.doubleValue(); 
} 
public String toString() { 
return i.toString(); 
} 
@Override 
public int hashCode() { 
final int prime = 31; 
int result = 1; 
result = prime * result + ((i == null) ? 0 : i.hashCode()); 
return result; 
} 
@Override 
public boolean equals(Object obj) { 
if (this == obj) return true; 
if (obj == null) return false; 
if (getClass() != obj.getClass()) return false; 
AtomicPositiveInteger other = (AtomicPositiveInteger) obj; 
if (i == null) { 
if (other.i != null) return false; 
} else if (!i.equals(other.i)) return false; 
return true; 
} 
}