Java多线程详解
# Java多线程详解
1. 线程简介
- 线程就是独立的执行路径
- 程序运行时，及时没有自己创建线程，后台也会有多个线程
- main()称之为主线程，为系统的入口，用于执行整个程序
- 在一个进程中，如果开辟了多了线程，线程的运行由调度器安排调度，调度器是与操作系统紧密相关，先后顺序是不能人为干预的
- 对同一份资源操作时，会存在资源抢夺的问题，需要键入并发控制
- 线程会带来额外的开销，如cpu调度时间，并发控制开销
- 每个线程在自己的工作内存交互，内存控制不当会造成数据不一致
2. 线程实现
2.1三种创建方式
2.2 Thread
线程是程序中执行的线程。 Java虚拟机允许应用程序同时执行多个执行线程
新建一个类 继承Thread 重写run()
package com.peng.demo01;
//练习Thread 实现多线程同步在下载图片
import org.apache.commons.io.FileUtils;
import java.io.File;
import java.io.IOException;
import java.net.URL;
public class TestThread2 extends Thread {
private String url; //网络图片地址
private String name;//保存的文件名
public TestThread2(String url, String name) {
this.url = url;
this.name = name;
}
//下载图片线程的执行体
@Override
public void run() {
//super.run();
WebDownloader webDownloader = new WebDownloader();
webDownloader.downloader(url, name);
System.out.println("下载了文件为：" + name);
}
public static void main(String[] args) {
TestThread2 t1 = new TestThread2("https://t7.baidu.com/it/u=1819248061,230866778&fm=193&f=GIF", "1.jpg");
TestThread2 t2 = new TestThread2("https://t7.baidu.com/it/u=4036010509,3445021118&fm=193&f=GIF", "2.jpg");
TestThread2 t3 = new TestThread2("https://t7.baidu.com/it/u=91673060,7145840&fm=193&f=GIF", "3.jpg");
t1.start();
t2.start();
t3.start();
}
}
//下载器
class WebDownloader {
public void downloader(String url, String name) {
try {
FileUtils.copyURLToFile(new URL(url), new File(name));
} catch (IOException e) {
e.printStackTrace();
System.out.println("IO异常，downloader方法出现问题");
}
}
}
2.3实现Runnable
另一种方法来创建一个线程是声明实现类Runnable接口。 那个类然后实现了run方法。 然后可以分配类的实例，在创建Thread时作为参数传递，并启动
package com.peng.demo01;
public class TestThread4 implements Runnable {
private String url; //网络图片地址
private String name;//保存的文件名
public TestThread4(String url, String name) {
this.url = url;
this.name = name;
}
//下载图片线程的执行体
@Override
public void run() {
//super.run();
WebDownloader webDownloader = new WebDownloader();
webDownloader.downloader(url, name);
System.out.println("下载了文件为：" + name);
}
public static void main(String[] args) {
TestThread2 t1 = new TestThread2("https://t7.baidu.com/it/u=1819248061,230866778&fm=193&f=GIF", "1.jpg");
TestThread2 t2 = new TestThread2("https://t7.baidu.com/it/u=4036010509,3445021118&fm=193&f=GIF", "2.jpg");
TestThread2 t3 = new TestThread2("https://t7.baidu.com/it/u=91673060,7145840&fm=193&f=GIF", "3.jpg");
new Thread(t1).start();
new Thread(t2).start();
new Thread(t3).start();
}
}
2.4 多个线程同时操作同一个对象
多个线程操作同一个资源的情况下，线程不安全，数据紊乱
package com.peng.demo01;
//多个线程操作同一个资源的情况下，线程不安全，数据紊乱
public class TestThread5 implements Runnable {
//票数
private int ticketNums = 10;
@Override
public void run() {
while (true){
if (ticketNums<=0){
break;
}
try {
Thread.sleep(200);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println(Thread.currentThread().getName()+"---拿到了第"+ticketNums--+"票");
}
}
public static void main(String[] args) {
TestThread5 testThread5 = new TestThread5();
new Thread(testThread5,"xm").start();
new Thread(testThread5,"ls").start();
new Thread(testThread5,"hn").start();
}
}
2.5模拟龟兔赛跑
package com.peng.demo01;
import java.util.TreeMap;
public class Race implements Runnable {
private static String winner;
@Override
public void run() {
for (int i = 0; i <= 100; i++) {
if (Thread.currentThread().getName().equals("兔子") && i % 10 == 0) {
try {
Thread.sleep(100);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
if (gameOver(i)) {
break;
}
System.out.println(Thread.currentThread().getName() + "--->跑了" + i + "步");
}
}
private boolean gameOver(int step) {
//判断时候有胜利者
if (winner != null) {
return true;
}
{
if (step >= 100) {
winner = Thread.currentThread().getName();
System.out.println("winner is " + winner);
return true;
}
}
return false;
}
public static void main(String[] args) {
Race race = new Race();
new Thread(race, "兔子").start();
new Thread(race, "乌龟").start();
}
}
2.6实现Callable接口
- 新建一个类实现Callable接口，需要返回值类型
- 重写call方法，需要抛出异常
- 创建目标对象
- 创建执行服务
- 提交执行
- 获取结果
- 关闭服务
package com.peng.demo02;
import org.apache.commons.io.FileUtils;
import java.io.File;
import java.io.IOException;
import java.net.URL;
import java.util.concurrent.*;
public class TestCallable implements Callable<Boolean> {
private String url; //网络图片地址
private String name;//保存的文件名
public TestCallable(String url, String name) {
this.url = url;
this.name = name;
}
@Override
public Boolean call() {
//super.run();
WebDownloader webDownloader = new WebDownloader();
webDownloader.downloader(url, name);
System.out.println("下载了文件为：" + name);
return true;
}
public static void main(String[] args) throws ExecutionException, InterruptedException {
TestCallable t1 = new TestCallable("https://t7.baidu.com/it/u=1819248061,230866778&fm=193&f=GIF", "1.jpg");
TestCallable t2 = new TestCallable("https://t7.baidu.com/it/u=4036010509,3445021118&fm=193&f=GIF", "2.jpg");
TestCallable t3 = new TestCallable("https://t7.baidu.com/it/u=91673060,7145840&fm=193&f=GIF", "3.jpg");
//创建执行服务
ExecutorService ser = Executors.newFixedThreadPool(3);
//提交执行
Future<Boolean> r1 = ser.submit(t1);
Future<Boolean> r2 = ser.submit(t2);
Future<Boolean> r3 = ser.submit(t3);
//获取结果
boolean res1 = r1.get();
boolean res2 = r2.get();
boolean res3 = r3.get();
//关闭服务
ser.shutdown();
}
}
//下载器
class WebDownloader {
public void downloader(String url, String name) {
try {
FileUtils.copyURLToFile(new URL(url), new File(name));
} catch (IOException e) {
e.printStackTrace();
System.out.println("IO异常，downloader方法出现问题");
}
}
}
2.7 静态代理模式
public class StaticProxy {
public static void main(String[] args) {
//You you = new You();
//WeddingCompany weddingCompany = new WeddingCompany(you);
//weddingCompany.HappyMarry();
new Thread(()-> System.out.println("我爱你")).start();
new WeddingCompany(new You()).HappyMarry();
}
}
interface Marry {
//人间四大喜事
//久旱逢甘霖
//他乡遇故知
//洞房花烛夜
//金榜题名时
void HappyMarry();
}
class You implements Marry{
@Override
public void HappyMarry() {
System.out.println("结婚啦！！！");
}
}
class WeddingCompany implements Marry {
private Marry target;
public WeddingCompany(Marry target) {
this.target = target;
}
@Override
public void HappyMarry() {
before();
this.target.HappyMarry();
after();
}
private void after() {
System.out.println("结婚后");
}
private void before() {
System.out.println("结婚前");
}
}
3.Lamda表达式
- 任何接口如果只包含唯一一个抽象方法，那么他就是函数式接口。
- 对于函数式接口，我们可以通过lambda表达式来创建该接口
package com.peng.lambda;
/*
*/
public class TestLambda1 {
//静态内部类
static class Like2 implements ILike {
@Override
public void lambda() {
System.out.println("I like myself2");
}
}
public static void main(String[] args) {
ILike like1 = new Like1();
like1.lambda();
ILike like2 = new Like2();
like2.lambda();
//局部内部类
class Like3 implements ILike {
@Override
public void lambda() {
System.out.println("I like myself3");
}
}
ILike like3 = new Like3();
like3.lambda();
//匿名内部类
ILike like4 = new ILike() {
@Override
public void lambda() {
System.out.println("I like myself4");
}
};
like4.lambda();
//lambda简化
ILike like5 = ()->{
System.out.println("I like myself5");
};
}
}
interface ILike {
void lambda();
}
class Like1 implements ILike{
@Override
public void lambda() {
System.out.println("I like myself1");
}
}
4.线程状态
4.1 停止线程
- 不推荐JDK提供的stop()，destory()方法。(已废弃)
- 推荐线程自己停止
- 建议使用一个标志位进行终止变量，当flag=false，则终止线程运行。
package com.peng.state;
public class TestThreadStop implements Runnable {
private boolean flag = true;
@Override
public void run() {
int i= 0;
while(flag){
System.out.println("run...Thread"+i++);
}
}
public void stop(){
this.flag=false;
}
public static void main(String[] args) {
TestThreadStop testThreadStop = new TestThreadStop();
new Thre ad(testThreadStop).start();
for (int i = 0; i < 1000; i++) {
if (i == 900) {
testThreadStop.stop();
System.out.println("线程该停止了");
}
}
}
}
4.2 线程休眠
package com.peng.state;
import java.text.SimpleDateFormat;
import java.util.Date;
//模拟是10秒倒计时
public class TestThreadSleep {
public static void main(String[] args) {
/*
try {
tenDown();
} catch (InterruptedException e) {
e.printStackTrace();
}
*/
//获取当前系统时间
Date startTime = new Date(System.currentTimeMillis());
while (true){
try {
Thread.sleep(1000);
System.out.println(new SimpleDateFormat("HH:mm:ss").format(startTime));
//更新当前时间
startTime=new Date(System. currentTimeMillis());
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println();
}
}
public static void tenDown() throws InterruptedException {
int num = 10;
while (true) {
Thread.sleep(1000);
System.out.println(num--);
if (num <= 0) {
break;
}
}
}
}
4.3线程礼让
- 礼让线程，让当前正在执行的线程暂停，但不阻塞
- 将线程从运行状态转为就绪状态
- 让cpu重新调度，礼让不一定成功
package com.peng.state;
public class TestThreadYield {
public static void main(String[] args) {
MyYield myYield = new MyYield();
new Thread(myYield,"a").start();
new Thread(myYield,"b").start();
}
}
class MyYield implements Runnable{
@Override
public void run() {
System.out.println(Thread.currentThread().getName()+"线程开始执行");
Thread.yield();
System.out.println(Thread.currentThread().getName()+"线程结束执行");
}
}
4.4 Join
- Join合并线程，待此线程执行完成后，再执行其他线程，其他线程阻塞
- 类似插队
package com.peng.state;
//测试join 想象为join
public class TestThreadJoin implements Runnable {
@Override
public void run() {
for (int i = 0; i < 1000; i++) {
System.out.println("线程VIP来了" + i);
}
}
public static void main(String[] args) throws InterruptedException {
TestThreadJoin testThreadJoin = new TestThreadJoin();
Thread thread = new Thread(testThreadJoin);
for (int i = 0; i < 500; i++) {
if (i == 200)
thread.join();
System.out.println("main" + i);
}
}
}
4.5 线程状态观测
Thread.State
- NEW 尚未启动
- RUNNABLE 执行
- BLOCKED 阻塞
- WAITING 等待
- TIMED_WAITING 等待时间
- TERMINATED 退出
package com.peng.state;
public class TestThreadState {
public static void main(String[] args) throws InterruptedException {
Thread thread = new Thread(() -> {
for (int i = 0; i < 5; i++) {
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
System.out.println(" Thread End");
});
//观察状态
Thread.State state = thread.getState();
System.out.println(state); //new
//观察启动后
thread.start(); //启动线程
state = thread.getState();
System.out.println(state); //RUNNABLE
while (state != Thread.State.TERMINATED) {
Thread.sleep(100);
state = thread.getState();
//TIMED_WAITING
//TERMINATED
System.out.println(state);
}
}
}
4.6线程优先级
-
Java提供一个线程调度器来监控程序启动后进入就绪状态的所有线程，线程调度器按照优先级决定应该调度哪个线程来执行。
-
线程的优先级用数字表示，范围1~10
-
使用getPriority() setPriority()获取或改变优先级
package com.peng.state;
//线程的优先级
public class TestThreadPriority extends Thread {
public static void main(String[] args) {
System.out.println(Thread.currentThread().getName() + "--->" + Thread.currentThread().getPriority());
MyPriority myPriority = new MyPriority();
Thread t1 = new Thread(myPriority);
Thread t2 = new Thread(myPriority);
Thread t3 = new Thread(myPriority);
Thread t4 = new Thread(myPriority);
Thread t5 = new Thread(myPriority);
Thread t6 = new Thread(myPriority);
t1.start();
//先设置优先级再启动
t2.setPriority(1);
t2.start();
t3.setPriority(4);
t3.start();
t4.setPriority(Thread.MAX_PRIORITY);
t4.start();
/*
t5.setPriority(-1);
t5.start();
t6.setPriority(11);
t6.start();
*/
}
}
class MyPriority implements Runnable {
@Override
public void run() {
System.out.println(Thread.currentThread().getName() + "--->" + Thread.currentThread().getPriority());
}
}
4.8守护线程
- 线程分为用户线程和守护线程
- 虚拟机必须确保用户线程执行完毕
- 虚拟机不用等待守护线程执行完毕
- 如 ：后台记录操作日志，监控内存，垃圾回收等待...
5.线程同步
5.1 线程安全
并发：同一个对象被多个线程同时操作
package com.peng.syn;
import com.sun.org.apache.bcel.internal.generic.ATHROW;
import java.util.ArrayList;
import java.util.List;
public class TestThreadUnsafeList {
public static void main(String[] args) {
List<String> list = new ArrayList<String>();
for (int i = 0; i < 100000; i++) {
new Thread(()->{
list.add(Thread.currentThread().getName());
}).start();
}
try {
Thread.sleep(3000);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println(list.size());
}
}
5.2同步方法
-
synchronized 方法和synchronized 快
public synchronized void method(int args){}
-
synchronized控制对象的访问，每个对象对应一把锁，每个synchronized方法都必须获得调用该方法的对象的锁才能执行，否则线程会阻塞，方法一旦执行，就独占该锁，直到该方法返回才释放锁，后面被阻塞的线程才能获得这个锁，继续执行。
package com.peng.syn;
import com.sun.org.apache.bcel.internal.generic.ATHROW;
import java.util.ArrayList;
import java.util.List;
public class TestThreadUnsafeList {
public static void main(String[] args) {
List<String> list = new ArrayList<String>();
for (int i = 0; i < 1000; i++) {
new Thread(()->{
synchronized (list){
list.add(Thread.currentThread().getName());
}
}).start();
}
try {
Thread.sleep(3000);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println(list.size());
}
}
5.4 JUC
package com.peng.syn;
import java.util.concurrent.CopyOnWriteArrayList;
public class TestJUC {
public static void main(String[] args) {
CopyOnWriteArrayList<String> list = new CopyOnWriteArrayList<>();
for (int i = 0; i < 10000; i++) {
new Thread(() -> {
list.add(Thread.currentThread().getName());
}).start();
}
try {
Thread.sleep(3000);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println(list.size());
}
}
5.5死锁
定义：
多个线程各自占有一些共享资源，并且互相等待其他线程占有的资源才能运行，而导致俩个或多个线程都在等待对方释放资源，都停止执行的情形。某一个同步块同时拥有"俩个以上对象的锁"时，就可能发生死锁。
如何避免死锁？
- 互斥条件：一个资源每次只能被一个进程使用
- 请求与保持条件：一个进程因请求资源而阻塞时，对已获得的资源保持不放
- 不剥脱条件：进程已获得的资源，在未使用之前，不能强行剥夺。
- 循环等待条件：若干进程之间形成一种头尾相接的循环等待资源关系。
package com.peng.lock;
//多个线程互相抱着对方需要的资源，然后形成僵持
public class DeadLock {
public static void main(String[] args) {
Makeup g1 = new Makeup(0, "灰");
Makeup g2 = new Makeup(1, "白");
g1.start();
g2.start();
}
}
//口红
class Lipstick{
}
//镜子
class Mirror{
}
class Makeup extends Thread {
static Lipstick lipstick = new Lipstick();
static Mirror mirror = new Mirror();
int choice;//选择
String girlName;// 使用者
public Makeup(int choice, String girl) {
this.choice = choice;
this.girlName = girl;
}
@Override
public void run() {
//super.run();
try {
makeup();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
private void makeup() throws InterruptedException {
if (choice == 0) {
synchronized (lipstick) {
System.out.println(this.girlName+"获得口红");
Thread.sleep(1000);
/*//会死锁
synchronized (mirror) {
System.out.println(this.girlName+"获得镜子");
}
*/
}
synchronized (mirror) {
System.out.println(this.girlName+"获得镜子");
}
} else {
synchronized (mirror) {
System.out.println(this.girlName+"获得镜子");
Thread.sleep(2000);
/*//会死锁
synchronized (lipstick) {
System.out.println(this.girlName+"获得口红");
}
*/
}
synchronized (lipstick) {
System.out.println(this.girlName+"获得口红");
}
}
}
}
5.6 Lock(锁)
5.6.1定义
- JDK5.0，Java提供了更强大的线程同步机制-----通过显示定义同步锁对象来实现同步。(同步锁对象Lock)
- java.utilconcurrent.locks.Lock接口是控制多个线程对共享资源进行访问的工具。锁提供了对共享资源的独占访问，每次只能有一个线程对Lock对象加锁，线程开始访问共享资源之前应该先获得Lock对象
- ReentrantLock(可重入锁)类实现了Lock，它拥有与synchronized相同的并发性和内存语音，在实现线程安全的控制中，比较常用的是ReetrantLock，可以显示加锁、释放锁。
package com.gaoji.lock;
import java.util.concurrent.locks.ReentrantLock;
//测试lock锁
public class TestLock {
public static void main(String[] args) {
TestLockImp testLockImp = new TestLockImp();
new Thread(testLockImp).start();
new Thread(testLockImp).start();
new Thread(testLockImp).start();
}
}
class TestLockImp implements Runnable{
int ticketNums = 10;
//定义lock锁
private final ReentrantLock lock = new ReentrantLock();
@Override
public void run() {
while (true) {
try {
//加锁
lock.lock();
if (ticketNums > 0) {
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println(ticketNums--);
} else {
break;
}
} finally {
//解锁
lock.unlock();
}
}
}
}
5.6.2 synchronized与lock的对比
- Lock是显示锁(手动开启和关闭锁)，synchronized是隐式锁，出了作用域自动释放
- Lock只有代码块锁，synchronized有代码块锁和方法锁
- 使用Lock锁，JVM话费较少的时间来调度线程，性能更好。并且具更好的扩展性(提供更多的子类)
- 优先使用顺序lock>同步代码块(进入方法体，分配了相应资源)>同步方法(在方法体之外)
6.线程协作
6.1线程通信
生产者和消费者
生产者和消费者共享同一个资源，并且生产者和消费者之间相互依赖，互为条件
6.2 管程法
- 生产者：负责生产数据的模块
- 消费者：负责出来数据的模块
- 缓冲如：消费者不能直接使用生产者的数据，他们之间有个"缓冲区"
生产者将生产好的数据放入缓冲区，消费者从缓冲区拿出数据
package com.gaoji.lock;
//测试生产者 消费者模型 --->利用缓冲区解决：管程法
//生产者 消费者 产品 缓冲去
public class TestPC {
public static void main(String[] args) {
SynContainer container = new SynContainer();
new Productor(container).start();
new Concumer(container).start();
}
}
//生产者
class Productor extends Thread{
SynContainer container;
public Productor(SynContainer container){
this.container=container;
}
@Override
public void run() {
for (int i = 0; i < 100; i++) {
container.push(new Chicken(i));
System.out.println("生产了"+i+"只鸡！！！");
}
}
}
//消费者
class Concumer extends Thread{
SynContainer container;
public Concumer(SynContainer container){
this.container=container;
}
@Override
public void run() {
for (int i = 0; i < 100; i++) {
System.out.println("消费了--->" + container.pop().id + "只鸡");
}
}
}
//产品
class Chicken{
int id;
public Chicken(int id) {
this.id = id;
}
}
//缓冲区
class SynContainer {
//容器
Chicken[] chickens = new Chicken[10];
//容器计数器
int count = 0;
//生产者放入产品
public synchronized void push(Chicken chicken) {
//如果容器满了 需要等待消费
if (count == chickens.length) {
//通知消费者消费
//生产等待
try {
this.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
//如果没有满 丢入产品
chickens[count] = chicken;
count++;
//可以通知消费者消费了
this.notifyAll();
}
//消费者消费产品
public synchronized Chicken pop() {
//判断能否消费
if (count == 0) {
//等待生产者生产 消费者等待
try {
this.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
count--;
Chicken chicken = chickens[count];
//消费完了 通知生产者生产
this.notifyAll();
return chicken;
}
}
6.4 信号灯法
package com.gaoji.lock;
import javax.print.DocFlavor;
public class TestPC2 {
public static void main(String[] args) {
TV tv = new TV();
new Player(tv).start();
new Watcher(tv).start();
}
}
//生产者
class Player extends Thread {
TV tv;
public Player(TV tv) {
this.tv = tv;
}
@Override
public void run() {
for (int i = 0; i < 20; i++) {
if (i%2==0){
this.tv.play("快乐大本营播放中");
}else{
this.tv.play("抖音记录美好生活");
}
}
}
}
//消费者
class Watcher extends Thread {
TV tv;
public Watcher(TV tv) {
this.tv = tv;
}
@Override
public void run() {
for (int i = 0; i < 20; i++) {
tv.watch();
}
}
}
class TV {
String voice;
boolean flag = true;
public synchronized void play(String voice) {
if (!flag){
try {
this.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
System.out.println("演员表演了：" + voice);
this.notifyAll();
this.voice = voice;
this.flag = !this.flag;
}
public synchronized void watch() {
if (flag) {
try {
this.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
System.out.println("观看了：" + voice);
this.notifyAll();
this.flag = !this.flag;
}
}
7.线程池
提前创建好多个线程，放入线程池中，使用时直接获取，使用完放回池中。可以避免频繁创建销毁、实现重复利用
- 提高响应速度
- 降低资源消耗
- 便于线程管理
JDK5.0提供了线程池相关API：ExecutorService和Executors
- void execute：执行任务 /命令，没有返回值，一般使用Runnable
Future submit(Callable task)：执行任务，又返回值，一般用来执行Callable - void shutdown()：关闭连接池
Executors：工具类、线程池的工厂类，用于创建并返回不同类型的线程池
package com.gaoji.lock;
import java.util.concurrent.Executor;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
public class TestThreadPool {
public static void main(String[] args) {
//1.创建服务 创建线程池
ExecutorService service = Executors.newFixedThreadPool(10);
//执行
service.execute(new MyThread());
service.execute(new MyThread());
service.execute(new MyThread());
service.execute(new MyThread());
service.execute(new MyThread());
//2.关闭连接
service.shutdown();
}
}
class MyThread implements Runnable {
@Override
public void run() {
System.out.println(Thread.currentThread().getName());
/*
for (int i = 0; i < 100; i++) {
System.out.println(Thread.currentThread().getName() + i);
}
*/
}
}
8.总结
package com.gaoji.lock;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.FutureTask;
public class ThreadNew {
public static void main(String[] args) {
new MyThread1().start();
new Thread(new MyThread2()).start();
FutureTask<Integer> futureTask = new FutureTask<Integer>(new MyThread3());
new Thread(futureTask).start();
try {
Integer integer = futureTask.get();
System.out.println(integer);
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}
}
}
//1.继承Thread类
class MyThread1 extends Thread{
@Override
public void run() {
System.out.println("MyThread1");
}
}
//2.实现Runnable
class MyThread2 implements Runnable{
@Override
public void run() {
System.out.println("MyThread2");
}
}
//3.实现Callble接口
class MyThread3 implements Callable<Integer> {
@Override
public Integer call() throws Exception {
System.out.println("MyThread3");
return 100;
}
}
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