浅谈java多线程wait，notify

前言

1.因为涉及到对象锁，Wait、Notify一定要在synchronized里面进行使用。
2.Wait必须暂定当前正在执行的线程,并释放资源锁,让其他线程可以有机会运行
3.notify/notifyall: 唤醒线程

共享变量

public class ShareEntity {
private String name;
// 线程通讯标识
private Boolean flag = false;
public ShareEntity() {
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Boolean getFlag() {
return flag;
}
public void setFlag(Boolean flag) {
this.flag = flag;
}
}

线程1（生产者）

public class CommunicationThread1 extends Thread{
private ShareEntity shareEntity;
public CommunicationThread1(ShareEntity shareEntity) {
this.shareEntity = shareEntity;
}
@Override
public void run() {
int num = 0;
while (true) {
synchronized (shareEntity) {
if (shareEntity.getFlag()) {
try {
shareEntity.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
if (num ％ 2 == 0)
shareEntity.setName("thread1-set-name-0");
else
shareEntity.setName("thread1-set-name-1");
num++;
shareEntity.setFlag(true);
shareEntity.notify();
}
}
}
}

线程2（消费者）

public class CommunicationThread2 extends Thread{
private ShareEntity shareEntity;
public CommunicationThread2(ShareEntity shareEntity) {
this.shareEntity = shareEntity;
}
@Override
public void run() {
while (true) {
synchronized (shareEntity) {
if (!shareEntity.getFlag()) {
try {
shareEntity.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
System.out.println(shareEntity.getName());
shareEntity.setFlag(false);
shareEntity.notify();
}
}
}
}

请求

@RequestMapping("test-communication")
public void testCommunication() {
ShareEntity shareEntity = new ShareEntity();
CommunicationThread1 thread1 = new CommunicationThread1(shareEntity);
CommunicationThread2 thread2 = new CommunicationThread2(shareEntity);
thread1.start();
thread2.start();
}

结果

thread1-set-name-0
thread1-set-name-1
thread1-set-name-0
thread1-set-name-1
thread1-set-name-0
thread1-set-name-1
thread1-set-name-0

来源：https://segmentfault.com/a/1190000019321936