Java并发编程示例代码-----ReentrantLock

public class ReenterLock implements Runnable{
    public static ReentrantLock lock=new ReentrantLock();
    public static int i=0;
    @Override
    public void run() {
        for(int j=0;j<10000000;j++){
            lock.lock();
            try{
                i++;
            }finally{
                lock.unlock();
            }
        }
    }
    public static void main(String[] args) throws InterruptedException {
        ReenterLock tl=new ReenterLock();
        Thread t1=new Thread(tl);
        Thread t2=new Thread(tl);
        t1.start();t2.start();
        t1.join();t2.join();
        System.out.println(i);
    }
}

 1 public class ReenterLock2 implements Runnable{
 2     public static ReentrantLock lock=new ReentrantLock();
 3     public static int i=0;
 4     @Override
 5     public void run() {
 6         for(int j=0;j<10000000;j++){
 7             lock.lock();
 8             lock.lock();
 9             try{
10                 i++;
11             }finally{
12                 lock.unlock();
13                 lock.unlock();
14             }
15         }
16     }
17     public static void main(String[] args) throws InterruptedException {
18         ReenterLock2 tl=new ReenterLock2();
19         Thread t1=new Thread(tl);
20         Thread t2=new Thread(tl);
21         t1.start();t2.start();
22         t1.join();t2.join();
23         System.out.println(i);
24     }
25 }