java 同步锁无效的解决办法

[qq_39459185]

多线程中，锁设置为this，却没起到锁的作用，输出结果依然是不同步的，为什么呢？



package lianxi1_duoxiancheng_2;

public class CeShi {
public static void main(String[] args) {
Mythread t1 = new Mythread("hello");
Mythread t2 = new Mythread("world");
t1.start();
t2.start();
}

static class Mythread extends Thread {
private String data;

public Mythread(String data) {
this.data = data;
}

public void run() {
synchronized (this) {//此处的this没起到锁的作用
for (int i = 0; i < 10; i++) {
try {
Thread.sleep((int) (Math.random() * 100));
} catch (Exception e) {
// TODO: handle exception
}
System.out.println(data);
}
}
}
}
}

[wautsns]

锁对象是两个不同的对象，有效就有鬼了，，，

[xiaovhao]

Mythread t1 = new Mythread("hello");
	
	Thread tt=new Thread(t1,"hello2");
	Thread t2=new Thread(t1,"world");

类似这样才对

[李德胜1995]

public class DD {
	private static final DD dd=new DD();
public static void main(String[] args) {
Mythread t1 = new Mythread("hello");
Mythread t2 = new Mythread("world");
t1.start();
t2.start();
}

static class Mythread extends Thread {
private String data;

public Mythread(String data) {
this.data = data;
}

public void run() {
synchronized (dd) {
for (int i = 0; i < 10; i++) {
try {
Thread.sleep((int) (Math.random() * 100));
} catch (Exception e) {
// TODO: handle exception
}
System.out.println(data);
}
}
}
}
}

[M义薄云天]

this代表当前对象，你new了两次就有两个对象，即两把锁，可以用static Object obj=new Object()的obj来代替

[bcvb]

this是当前对象，你new两个就是不同的对象了