简单的线程通信，一个线程对数字进行增加操作、另一个线程对线程进行减少操作。
简单解释：线程A对数字进行减少操作，但不会一直让这个数字减少下去。当减少到设定的条件，让其等待，通知其他线程获得该资源。
package com.ProductAndCustomer;
/**
* 线程之间的通信,生产者和消费者问题
*/
public class Product {
public static void main(String[] args) {
Data data = new Data();
new Thread(()->{
for (int i = 0; i < 10; i++) {
try {
data.increment();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
},"A").start();
new Thread(()->{
for (int i = 0; i < 10; i++) {
try {
data.decrement();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
},"B").start();
}
}
//等待,业务,通知
class Data{
//资源类
private int num = 0;
//增加操作
public synchronized void increment() throws InterruptedException {
if(num != 0){
//等待
this.wait();
}
num ++;
System.out.println(Thread.currentThread().getName()+"=>"+num);
//通知其他线程,+1结束
this.notifyAll();
}
//减少操作
public synchronized void decrement() throws InterruptedException {
if(num == 0){
//等待
this.wait();
}
num --;
System.out.println(Thread.currentThread().getName()+"=>"+num);
//通知其他线程,-1结束
this.notifyAll();
}
}测试
在多几个线程
package com.ProductAndCustomer;
/**
* 线程之间的通信,生产者和消费者问题
*/
public class Product {
public static void main(String[] args) {
Data data = new Data();
new Thread(()->{
for (int i = 0; i < 10; i++) {
try {
data.increment();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
},"A").start();
new Thread(()->{
for (int i = 0; i < 10; i++) {
try {
data.decrement();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
},"B").start();
new Thread(()->{
for (int i = 0; i < 10; i++) {
try {
data.decrement();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
},"C").start();
new Thread(()->{
for (int i = 0; i < 10; i++) {
try {
data.decrement();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
},"D").start();
}
}
//等待,业务,通知
class Data{
//资源类
private int num = 0;
//增加操作
public synchronized void increment() throws InterruptedException {
if(num != 0){
//等待
this.wait();
}
num ++;
System.out.println(Thread.currentThread().getName()+"=>"+num);
//通知其他线程,+1结束
this.notifyAll();
}
//减少操作
public synchronized void decrement() throws InterruptedException {
if(num == 0){
//等待
this.wait();
}
num --;
System.out.println(Thread.currentThread().getName()+"=>"+num);
//通知其他线程,-1结束
this.notifyAll();
}
}测试结果
这里会出现虚假唤醒
查看开发文档可知、需要修改判断语句 if修改为while
修改后的代码
package com.ProductAndCustomer;
/**
* 线程之间的通信,生产者和消费者问题
*/
public class Product {
public static void main(String[] args) {
Data data = new Data();
new Thread(()->{
for (int i = 0; i < 5; i++) {
try {
data.increment();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
},"A").start();
new Thread(()->{
for (int i = 0; i < 5; i++) {
try {
data.decrement();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
},"B").start();
new Thread(()->{
for (int i = 0; i < 5; i++) {
try {
data.increment();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
},"C").start();
new Thread(()->{
for (int i = 0; i < 5; i++) {
try {
data.decrement();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
},"D").start();
}
}
//等待,业务,通知
class Data{
//资源类
private int num = 0;
//增加操作
public synchronized void increment() throws InterruptedException {
while(num != 0){
//等待
this.wait();
}
num ++;
System.out.println(Thread.currentThread().getName()+"=>"+num);
//通知其他线程,+1结束
this.notifyAll();
}
//减少操作
public synchronized void decrement() throws InterruptedException {
while(num == 0){
//等待
this.wait();
}
num --;
System.out.println(Thread.currentThread().getName()+"=>"+num);
//通知其他线程,-1结束
this.notifyAll();
}
}测试结果
