标签：public number override final 实现 r++ his [] syn
1、同步线程状态图
2、怎么实现同步
线程间的相互作用
wait and notify
The pools:
Wait pool
Lock pool
3、实例
场景： 常量number，当number是1是可以进行减1操作，当number为0时可以进行加1操作
1）Sample类
public class Sample {
private int number;
public synchronized void increase(){
while(number != 0){
try {
wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
number++;
System.out.println(number);
notify();
}
public synchronized void decrease(){
while(number == 0){
try {
wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
number--;
System.out.println(number);
notify();
}
}
2）IncreaseThread 线程
public class IncreaseThread extends Thread {
private Sample sample;
public IncreaseThread (Sample sample) {
this.sample = sample;
}
@Override
public void run() {
for(int i = 0; i<20; i++){
try {
Thread.sleep((long)(Math.random() * 1000));
} catch (InterruptedException e) {
e.printStackTrace();
}
sample.increase();
}
}
}
3）、DecreaseThread 类
public class DecreaseThread extends Thread {
private Sample sample;
public DecreaseThread (Sample sample) {
this.sample = sample;
}
@Override
public void run() {
for(int i = 0; i<20; i++){
try {
Thread.sleep((long)(Math.random() * 1000));
} catch (InterruptedException e) {
e.printStackTrace();
}
sample.decrease();
}
}
}
4） 测试
public class MainTest {
public static void main(String[] args) {
Sample sample = new Sample();
Thread t1 = new IncreaseThread(sample);
Thread t2 = new DecreaseThread(sample);
Thread t3 = new IncreaseThread(sample);
Thread t4 = new DecreaseThread(sample);
t1.start();
t2.start();
t3.start();
t4.start();
}
}
5）执行结果
1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0
4、总结
1）wait与notif方法都是定义在Object类中，而且是final的，因此会被所有的Java类所继承并且无法重写。这两个方法要求在调用线程应该已经获得了对象的锁，因此对这两个方法的调用需要放在synchronized方法或块中。当线程执行了wait方法时，它会释放掉对象的锁。
2）另一个会导致线程暂停的方法就是Thread类中的sleep方法，它会导致线程睡眠指定的毫秒数，但线程在睡眠的过程中是不会释放掉对象的锁的。
标签：public number override final 实现 r++ his [] syn
原文地址：https://www.cnblogs.com/linlf03/p/10849972.html
