/**
*  PairManager是实现了线程安全的类，它将线程不安全的Pair类
*  置于其内部，是的Pair被保护起来
* @author Administrator
*/
abstract class PairManager{
    protected Pair p = new Pair();
    private List<Object> storage = new ArrayList<Object>()   
    public synchronized Pair getPair(){
        return new Pair(p.getX(),p.getY());
    }  
    protected void store(){
        storage.add(getPair());
    }   
    public abstract void doTask();
}
class PairMangerMethod extends PairManager{

    @Override
    public synchronized void doTask() {
        p.incrementX();
        p.incrementY();
        store();
    }   
}/**
* 使用临界区，也就是同步块了
* @author Administrator
*/
class PairManagerCriticalSetion extends PairManager{
    @Override
    public void doTask() {
        synchronized (this) {
            p.incrementX();
            p.incrementY();
        }
        store();
    }   
}
class PairManipulator extends Thread{
    private PairManager pm;
    private int checkCounter = 0;    
    private class PairChecker extends Thread{
        PairChecker(){
            start();
        }       
        public void run(){
            while(true){
                checkCounter++;
                pm.getPair().checkState();
            }
        }
    }   
    public PairManipulator(PairManager pm){
        this.pm = pm;
        start();
        new PairChecker();
    }   
    public void run(){
        while(true){
            pm.doTask();
        }
    }
    @Override
    public String toString() {
        return "PairManipulator [pm=" + pm.getPair() + ", checkCounter=" + checkCounter
                + "]";
    }      
}
public class CriticalSection {  
    public static void main(String[] args) {
        final PairManipulator
            pm1 = new PairManipulator(new PairMangerMethod()),
            pm2 = new PairManipulator(new PairManagerCriticalSetion());
        new Timer(true).schedule(new TimerTask() {           
            @Override
            public void run() {
                System.out.println("pm1:" + pm1);
                System.out.println("pm2:" + pm2);
                System.exit(0);
            }
        }, 1000);
    }  
}