package com.Thread;
class W12306 implements Runnable{
private boolean flag = true;
private int num =10;
@Override
public void run() {
while(flag ) {
test6();
}
}
//线程不安全，锁定不正确，一般锁定对象
public void test6() {
if(num <=0) {
flag = false ;
return;
}
synchronized(this ) {
try {
Thread. sleep(500);//模拟网络延时，最后取到了0和-1
} catch (InterruptedException e) {
e.printStackTrace();
}
System. out.println(Thread.currentThread().getName() + "抢到了" + num--);
}
}
//线程不安全，锁定资源不正确
public void test5() {
synchronized((Integer)num ) {
if(num <=0) {
flag = false ;
return;
}
try {
Thread. sleep(500);//模拟网络延时，最后取到了0和-1
} catch (InterruptedException e) {
e.printStackTrace();
}
System. out.println(Thread.currentThread().getName() + "抢到了" + num--);
}
}
//线程不安全，锁定范围过小
//a b c
public void test4() {
synchronized(this ) {
//b
if(num <=0) {
flag = false ;
return;
}
}
//b
try {
Thread. sleep(500);//模拟网络延时，最后取到了0和-1
} catch (InterruptedException e) {
e.printStackTrace();
}
System. out.println(Thread.currentThread().getName() + "抢到了" + num --);
//a-->1
}
//线程安全，锁定方法块
public void test3() {
synchronized(this ) {
if(num <=0) {
flag = false ;
return;
}
try {
Thread. sleep(500);//模拟网络延时，最后取到了0和-1
} catch (InterruptedException e) {
e.printStackTrace();
}
System. out.println(Thread.currentThread().getName() + "抢到了" + num--);
}
}
//线程安全，锁定方法
public synchronized void test2() {
if(num <=0) {
flag = false ;
return;
}
try {
Thread. sleep(500);//模拟网络延时，最后取到了0和-1
} catch (InterruptedException e) {
e.printStackTrace();
}
System. out.println(Thread.currentThread().getName() + "抢到了" + num --);
}
//线程不安全
public void test1() {
if(num <0) {
flag = false ;
}
try {
Thread. sleep(500);//最后取到了0和-1
} catch (InterruptedException e) {
e.printStackTrace();
}
System. out.println(Thread.currentThread().getName() + "抢到了" + num --);
}
}
public class Synchronized_ {
public static void main(String[] args) {
W12306 w = new W12306();
Thread t1 = new Thread(w, "甲" );
Thread t2 = new Thread(w, "已" );
Thread t3 = new Thread(w, "丁" );
t2.start();
t1.start();
t3.start();
}
}
