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MyLock.java 锁对象代码:
package cn.itcast.dieLock;
public class MyLock {
public static Object Lock1 = new Object();
public static Object Lock2 = new Object();
}
DieLock.java:
package cn.itcast.dieLock;
public class DieLock implements Runnable {
private boolean flag;
public DieLock(boolean flag){
this.flag = flag;
}
@Override
public void run() {
if(flag){
synchronized (MyLock.Lock1) {
System.out.println("if Lock1");
synchronized (MyLock.Lock2) {
System.out.println("if Lock2");
}
}
}else{
synchronized (MyLock.Lock2) {
System.out.println("else Lock2");
synchronized (MyLock.Lock1) {
System.out.println("else Lock1");
}
}
}
}
}
DieLockTest.java 测试类:
package cn.itcast.dieLock;
/**
* 同步的弊端
* A:效率低
* B:容易产生死锁
*
* 死锁:
* 两个或两个以上的线程在争夺资源的过程中,发生的一种相互等待的现象
*
* 举例:
* 中国人,美国人吃饭案例
* 正常情况下:
* 中国人:筷子两支
* 美国人:刀和叉
* 现在:
* 中国人:筷子一支,刀一把
* 美国人:筷子一支,叉一把
*/
public class DieLockTest {
public static void main(String[] args) {
DieLock d1 = new DieLock(true);
DieLock d2 = new DieLock(false);
Thread t1 = new Thread(d1);
Thread t2 = new Thread(d2);
t1.start();
t2.start();
}
}