多线程
Thread：
package com.kuang.demo01;
// 创建线程方式一：继承Thread类，重写run（）方法，调用start开启线程
//总结：注意，线程开启不一定立即执行，由CPU调度执行
public class TestThread1 extends Thread{
@Override
public void run() {
// run方法线程体
for (int i = 0; i < 20; i++) {
System.out.println("我在看代码---"+i);
}
}
public static void main(String[] args) {
// main线程，主线程
//创建一个线程对象
TestThread1 testThread1 = new TestThread1();
//调用start()方法开始线程
testThread1.start();
for (int i = 0; i < 200; i++) {
System.out.println("我在学习多线程--"+i);
}
}
}
实现多线程同步下载图片：
package com.kuang.demo01;
import org.apache.commons.io.FileUtils;
import java.io.File;
import java.io.IOException;
import java.net.URL;
//联系Thread，实现多线程同步下载图片
public class TestThread2 implements Runnable{
private String url;
private String name;
public TestThread2(String url,String name){
this.url = url;
this.name = name;
}
//下载图片的线程执行体
@Override
public void run() {
WebDownloader webDownloader = new WebDownloader();
webDownloader.downloader(url,name);
System.out.println("下载了文件名为："+name);
}
public static void main(String[] args) {
TestThread2 t1 = new TestThread2("https://img-blog.csdnimg.cn/f1ff6c58ec2a43b58454c9be67ebc2da.png?x-oss-process=image/resize,m_fixed,h_300,image/format,png","1.jpg");
TestThread2 t2 = new TestThread2("https://img-blog.csdnimg.cn/f1ff6c58ec2a43b58454c9be67ebc2da.png?x-oss-process=image/resize,m_fixed,h_300,image/format,png","2.jpg");
TestThread2 t3 = new TestThread2("https://img-blog.csdnimg.cn/f1ff6c58ec2a43b58454c9be67ebc2da.png?x-oss-process=image/resize,m_fixed,h_300,image/format,png","3.jpg");
new Thread(t1).start();
new Thread(t2).start();
new Thread(t3).start();
}
}
//下载器
class WebDownloader{
//下载方法
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");
}
}
}
实现runnable接口：
package com.kuang.demo01;
//创建线程方式二：实现runnable接口，重写run方法，执行线程需要先丢入runnable接口实现类，调用start方法
public class TestThread3 implements Runnable{
@Override
public void run() {
// run方法线程体
for (int i = 0; i < 20; i++) {
System.out.println("我在看代码---"+i);
}
}
public static void main(String[] args) {
//创建一个runnable接口的实现类对象
TestThread3 testThread3 = new TestThread3();
//创建线程对象，通过线程对象来开启我们的线程，代理
// Thread thread = new Thread(testThread3);
// thread.start();
new Thread(testThread3).start();
for (int i = 0; i < 200; i++) {
System.out.println("我在学习多线程--"+i);
}
}
}
多线程模拟买火车票：
package com.kuang.demo01;
//多个线程同时操作同一个对象
//买火车票的例子
//发现问题：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 TestThread4 implements Runnable{
//票数
private int ticketNums = 10;
@Override
public void run() {
while (true){
if (ticketNums<=0){
break;
}
//模拟延时
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) {
TestThread4 ticket = new TestThread4();
new Thread(ticket,"小明").start();
new Thread(ticket,"老师").start();
new Thread(ticket,"薇薇").start();
}
}
龟兔赛跑：
package com.kuang.demo01;
//模拟龟兔赛跑
public class Race implements Runnable{
//胜利者
private static String winner;
@Override
public void run() {
for (int i = 0; i <= 100; i++) {
//模拟兔子休息
if (Thread.currentThread().getName().equals("兔子")&& i%10==0){
try {
Thread.sleep(1);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
//判断是否比赛结束
boolean flag = gameOver(i);
//如果比赛结束了，就停止程序
if (flag){
break;
}
System.out.println(Thread.currentThread().getName()+"-->跑了"+i+"步");
}
}
//判断是否完成比赛
private boolean gameOver(int steps){
//判断是否有胜利者
if (winner!=null){
return true;
}{
if (steps>=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();
}
}
实现callable接口：
package com.kuang.demo02;
import com.kuang.demo01.TestThread2;
import org.apache.commons.io.FileUtils;
import java.io.File;
import java.io.IOException;
import java.net.URL;
import java.util.concurrent.*;
//线程创建方式三：实现callable接口
/*
callable的好处
1.可以定义返回值
2.可以抛出异常.
*/
public class TestCallable implements Callable<Boolean> {
private String url;
private String name;
public TestCallable(String url,String name){
this.url = url;
this.name = name;
}
//下载图片的线程执行体
@Override
public Boolean call() {
WebDownloader webDownloader = new WebDownloader();
webDownloader.downloader(url,name);
System.out.println("下载了文件名为："+name);
return true;
}
public static void main(String[] args) throws ExecutionException, InterruptedException {
TestCallable t1 = new TestCallable("https://img-blog.csdnimg.cn/f1ff6c58ec2a43b58454c9be67ebc2da.png?x-oss-process=image/resize,m_fixed,h_300,image/format,png","1.jpg");
TestCallable t2 = new TestCallable("https://img-blog.csdnimg.cn/f1ff6c58ec2a43b58454c9be67ebc2da.png?x-oss-process=image/resize,m_fixed,h_300,image/format,png","2.jpg");
TestCallable t3 = new TestCallable("https://img-blog.csdnimg.cn/f1ff6c58ec2a43b58454c9be67ebc2da.png?x-oss-process=image/resize,m_fixed,h_300,image/format,png","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 rs1 = r1.get();
boolean rs2 = r1.get();
boolean rs3 = r1.get();
System.out.println(rs1);
System.out.println(rs2);
System.out.println(rs3);
//关闭服务
ser.shutdownNow();
}
}
//下载器
class WebDownloader{
//下载方法
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");
}
}
}
测试Lock锁：
package com.kuang.gaoji;
import java.util.concurrent.locks.ReentrantLock;
//测试Lock锁
public class TestLock {
public static void main(String[] args) {
TestLock2 testLock2 = new TestLock2();
new Thread(testLock2).start();
new Thread(testLock2).start();
new Thread(testLock2).start();
}
}
class TestLock2 implements Runnable{
int ticketNums = 10;
//定义lock锁
private ReentrantLock lock = new ReentrantLock();
@Override
public void run() {
while (true){
try {
lock.lock();//加锁
if (ticketNums>0){
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println(ticketNums--);
}else{
break; }
} finally {
//解锁
lock.unlock();
}
}
}
}
生产者消费者模型：
package com.kuang.gaoji;
//测试：生产者消费者模型-->利用缓冲区解决：管理法
//生产者：消费者 ，产品 ，缓冲区
public class TestPC {
public static void main(String[] args) {
SynContainer container = new SynContainer();
new Productor(container).start();
new Consumer(container).start();
}
}
//生产者
class Productor extends Thread{
SynContainer container;
public Productor(SynContainer container){
this.container = container;
}
//生产
@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 Consumer extends Thread{
SynContainer container;
public Consumer(SynContainer container){
this.container = container;
}
//消费
@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;//产品编号
public Chicken(int id) {
this.id = id;
}
}
//缓冲区
class SynContainer{
//需要一个容器大小
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，就需要等待消费者
if (count==chickens.length){
try {
this.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
//吃完了，通知消费者，生产等待
}
//如果没有满，我们就需要丢入产品
chickens[count]=chicken;
count++;
//可以通知消费者了
this.notifyAll();
}
//消费者消费产品
public synchronized Chicken pop() {
//判断是否消费
if (count == 0) {
//等待消费者生产，消费者等待
try {
this.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
//如果可以消费
count--;
Chicken chicken = chickens[count];
//吃完了，通知生费者生产
this.notifyAll();
return chicken;
}
}测试生产者消费者问题2：
信号灯法，标志位解决：
package com.kuang.gaoji;
//测试生产者消费者问题2：信号灯法，标志位解决
public class TestPC2 {
public static void main(String[] args) {
TV tv = new TV();
new Player(tv).start();
new Watcher(tv).start();
}
}
//生产者-->演员
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-->观众
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();
}
}
}
//产品-->节目
class TV{
//演员表演，观众等待 T
//观众观看，演员等待 F
String voice;//表演的节目
boolean flag = true;
//表演
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);
//通知观众观看
this.notifyAll();//通知唤醒
this.voice = voice;
this.flag = !this.flag;
}
//观看
public synchronized void watch(){
if (flag){
try {
this.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
System.out.println("观看了"+voice);
//通知演员表演
this.notifyAll();
this.flag = !this.flag;
}
}测试线程池：
package com.kuang.gaoji;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
//测试线程池
public class TestPool {
public static void main(String[] args) {
//1.创建服务，创建线程池
//newFixedThreadPool 参数为：线程池大小
ExecutorService service = Executors.newFixedThreadPool(10);
//执行
service.execute(new MyThread());
service.execute(new MyThread());
service.execute(new MyThread());
service.execute(new MyThread());
//关闭连接
service.shutdownNow();
}
}
class MyThread implements Runnable{
@Override
public void run() {
System.out.println(Thread.currentThread().getName());
}
}回顾总线程的创建：
package com.kuang.gaoji;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.FutureTask;
//回顾总线程的创建
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 接口
class MyThread2 implements Runnable{
@Override
public void run() {
System.out.println("MyThread2");
}
}
//3.实现Callable 接口
class MyThread3 implements Callable<Integer>{
@Override
public Integer call() throws Exception {
System.out.println("MyThread3");
return 100;
}
}测试守护线程：
package com.kuang.state;
//测试守护线程
//上帝守护你
public class TesDaemon {
public static void main(String[] args) {
God god = new God();
You you = new You();
Thread thread = new Thread(god);
thread.setDaemon(true);//默认是false表示是用户线程，正常的线程都是用户线程...
thread.start();//上帝守护线程启动
new Thread(you).start();//你 用户线程启动...
}
}
//上帝
class God implements Runnable{
@Override
public void run() {
while (true){
System.out.println("上帝守护着你");
}
}
}
//你
class You implements Runnable{
@Override
public void run() {
for (int i = 0; i < 36500; i++) {
System.out.println("你一生都开心的活着!");
}
System.out.println("========goodbye! world===========");//Hello world！
}
}测试join方法：
package com.kuang.state;
//测试join方法 想象为插队
public class TestJoin implements Runnable{
@Override
public void run() {
for (int i = 0; i < 100; i++) {
System.out.println("线程vip来了"+i);
}
}
public static void main(String[] args) throws InterruptedException {
//启动我们的线程
TestJoin testJoin = new TestJoin();
Thread thread = new Thread(testJoin);
thread.start();
//主线程
for (int i = 0; i < 1000; i++) {
if (i==200){
thread.join();//插队
}
System.out.println("main"+i);
}
}
}测试线程的优先级：
package com.kuang.state;
//测试线程的优先级
public class TestPriority {
public static void main(String[] args) {
//测试主线程的优先级
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);
//先设置优先级，在启动
t1.start();
t2.setPriority(1);
t2.start();
t3.setPriority(Thread.MAX_PRIORITY);//MAX_PRIORITY = 10
t3.start();
t4.setPriority(4);
t4.start();
t5.start();
t6.setPriority(8);
t6.start();
}
}
class MyPriority implements Runnable{
@Override
public void run() {
System.out.println(Thread.currentThread().getName()+"-->"+Thread.currentThread().getPriority());
}
}模拟网络延时:放大问题的发生性：
package com.kuang.state;
import com.kuang.demo01.TestThread4;
//模拟网络延时:放大问题的发生性
public class TestSleep implements Runnable{
//票数
private int ticketNums = 10;
@Override
public void run() {
while (true){
if (ticketNums<=0){
break;
}
//模拟延时
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) {
TestSleep ticket = new TestSleep();
new Thread(ticket,"小明").start();
new Thread(ticket,"老师").start();
new Thread(ticket,"薇薇").start();
}
}模拟倒计时：
package com.kuang.state;
import java.text.SimpleDateFormat;
import java.util.Date;
//模拟倒计时
public class TestSleep2 {
public static void main(String[] args) {
// try {
// tenDown();
// } catch (InterruptedException e) {
// e.printStackTrace();
// }
Date startTime = new Date(System.currentTimeMillis());//更新系统当前时间
while (true){
try {
Thread.sleep(1000);
System.out.println(new SimpleDateFormat("HH:mm:ss").format(startTime));
startTime = new Date(System.currentTimeMillis());//更新当前时间
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
public static void tenDown() throws InterruptedException {
int num = 10;
while (true){
Thread.sleep(1000);
System.out.println(num--);
if (num<=0){
break;
}
}
}
}观察测试线程的状态：
package com.kuang.state;
//观察测试线程的状态
public class TestState {
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("///////");
});
//观察状态
Thread.State state = thread.getState();
System.out.println(state);
//观察启动后
thread.start();//启动线程
state = thread.getState();
System.out.println(state);//Run
//只要线程不终止，就一直输出
while (state != Thread.State.TERMINATED){
Thread.sleep(100);
state = thread.getState();//更新线程状态
System.out.println(state);//输出状态
}
}
}测试stop：
package com.kuang.state;
//测试stop
//1、建议线程正常停止-->利用次数，不建议死循环
//2、建议使用标志位-->设置一个标志位
//3、不要使用stop或者destroy等过时或者JDK不推荐的方法
public class TestStop implements Runnable{
//1、设置一个标志位
private boolean flag = true;
@Override
public void run() {
int i = 0;
while (flag){
System.out.println("run...Thread"+i);
}
}
//2、设置一个公开的方法停止线程，转换标志位
public void stop(){
this.flag = flag;
}
public static void main(String[] args) {
TestStop testStop = new TestStop();
new Thread(testStop).start();
for (int i = 0; i < 1000; i++) {
System.out.println("main"+i);
if (i==900){
//调用stop方法 切换标志位，让线程停止
testStop.stop();
System.out.println("线程该停止了");
}
}
}
}测试礼让线程：
package com.kuang.state;
//测试礼让线程
//礼让不一定成功，看CPU心情
public class TestYield {
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();//礼让
System.out.println(Thread.currentThread().getName()+"线程停止执行");
}
}测试不安全的集合：
package com.kuang.syn;
import java.util.concurrent.CopyOnWriteArrayList;
//测试不安全的集合
public class TestJUC {
public static void main(String[] args) {
CopyOnWriteArrayList<String> list = new CopyOnWriteArrayList<String>();
for (int i = 0; i < 10000; i++) {
new Thread(()->{
list.add(Thread.currentThread().getName());
}).start();
}
try {
Thread.sleep(3000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}优化：
package com.kuang.syn;
import java.util.ArrayList;
import java.util.List;
//线程不安全集合
public class UnisafeList {
public static void main(String[] args) {
List<String> list = new ArrayList<String>();
for (int i = 0; i < 10000; 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());
}
}银行取钱：
package com.kuang.syn;
import java.awt.image.PackedColorModel;
//不安全的取钱
//两个人去银行取钱
public class UnsafeBank {
public static void main(String[] args) {
//账户
Account account = new Account(1000,"结婚基金");
Drawing you= new Drawing(account,50,"你");
Drawing girlFriend= new Drawing(account,100,"girlFriend");
you.start();
girlFriend.start();
}
}
//账户
class Account{
int money;//余额
String name;//卡名
public Account(int money, String name) {
this.money = money;
this.name = name;
}
}
//银行：模拟取款
class Drawing extends Thread{
Account account;//账户
//取了多少钱
int drawingMoney;
//现在手里有多少钱
int nowMoney;
public Drawing(Account account,int drawingMoney,String name){
super(name);
this.account = account;
this.drawingMoney = drawingMoney;
}
//取钱
//synchronized 默认的锁是this
@Override
public void run() {
//锁的对象是变化的量，需要增删改的对象
synchronized (account){
//判断是否有钱
if (account.money-drawingMoney<0){
System.out.println(Thread.currentThread().getName()+"钱不够，取不了");
return;
}
//sleep可以放大问题的发生性
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
//卡内余额 = 余额 - 你取的钱
account.money = account.money-drawingMoney;
//你手里的钱
nowMoney = nowMoney + drawingMoney;
System.out.println(account.name+"余额为:"+account.money);
//Thread.currentThread().getName() = this.getName()
System.out.println(this.getName()+"手里的钱："+nowMoney);
}
}
}买票：
package com.kuang.syn;
//不安全的买票
public class UnsafeBuyTicket {
public static void main(String[] args) {
BuyTicket station = new BuyTicket();
new Thread(station,"苦逼的我").start();
new Thread(station,"牛逼的你们").start();
new Thread(station,"可恶的黄牛党").start();
}
}
class BuyTicket implements Runnable{
//票
private int ticketNums = 10;
boolean flag = true;//外部的停止方式
@Override
public void run() {
//买票
while (flag){
try {
buy();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
//synchronized 同步方法 ，锁的是this
private synchronized void buy() throws InterruptedException {
//判断是否有票
if (ticketNums<=0){
flag = false;
return;
}
//模拟延时
Thread.sleep(100);
//买票
System.out.println(Thread.currentThread().getName()+"拿到"+ticketNums--);
}
}静态代理
模拟结婚：
//静态代理模式总结
//真是对象和代理对象都要实现同一个接口
//代理对象要代理真是角色
//好处：
//代理对象可以做很多真实对象做不了的事情
//真是对象专注做自己的事情
public class StaticProxy {
public static void main(String[] args) {
You you = new You();//你要结婚
new Thread( ()-> System.out.println("我爱你")).start();
new WeddingCompany(new You()).HappyMarry();
// WeddingCompany weddingCompany = new WeddingCompany(you);
// weddingCompany.HappyMarry();
}
}
interface Marry{
void HappyMarry();
}
//真实角色，你去结婚
class You implements Marry{
@Override
public void HappyMarry() {
System.out.println("秦老师要结婚了，超开心");
}
}
//代理角色，帮助你去结婚
class WeddingCompany implements Marry{
//代理唯一>真实目标角色
private Marry target;
public WeddingCompany(Marry target){
this.target = target;
}
@Override
public void HappyMarry() {
before();
this.target.HappyMarry();//这就是真实对象
after();
}
private void after() {
System.out.println("结婚之后，收尾款");
}
private void before() {
System.out.println("结婚之前，布置现场");
}
}死锁（deadlock）
package com.kuang;
//死锁：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,"灰姑娘");
Makeup g2 = new Makeup(1,"白雪公主");
g1.start();
g2.start();
}
}
//口红
class Lipstick{
}
//镜子
class Mirror{
}
class Makeup extends Thread{
//需要的资源只有一份，用static来保证只有一份
static Lipstick lipstick = new Lipstick();
static Mirror mirror = new Mirror();
int choice;//选择
String girlName;//使用化妆品的人
Makeup(int choice,String girlName){
this.choice = choice;
this.girlName = girlName;
}
@Override
public void run() {
//化妆
try {
makeup();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
//化妆：互相持有对方的锁 ，就是拿到对方的资源
private void makeup() throws InterruptedException {
if (choice == 0) {
synchronized (lipstick) {//获得口红的锁
System.out.println(this.girlName + "获得口红的锁");
Thread.sleep(1000);
}
synchronized (mirror) {//一秒后想获得镜子
System.out.println(this.girlName + "获得镜子的锁");
}
} else {
synchronized (mirror) {//获得镜子的锁
System.out.println(this.girlName + "获得镜子的锁");
Thread.sleep(2000);
}
synchronized (lipstick) {//一秒后想获得口红
System.out.println(this.girlName + "获得口红的锁");
}
}
}
}lambda
一、Test
package com.kuang.lambda;
/*
推到lambda表达式
*/
public class TestLambda1 {
//3、静态内部类
static class Like2 implements ILike{
@Override
public void lambda() {
System.out.println("I like lambda2");
}
}
public static void main(String[] args) {
ILike like = new Like();
like.lambda();
like = new Like2();
like.lambda();
//4、局部内部类
class Like3 implements ILike{
@Override
public void lambda() {
System.out.println("I like lambda3");
}
}
like = new Like3();
like.lambda();
//5、匿名内部类，没有类的名称，必须借助接口或者父类
like = new ILike() {
@Override
public void lambda() {
System.out.println("I like lambda4");
}
};
like.lambda();
//6、用lambda简化
like = ()->{
System.out.println("I like lambda5");
};
like.lambda();
}
}
//1、定义一个函数式接口
interface ILike{
void lambda();
}
//2.实现类
class Like implements ILike{
@Override
public void lambda() {
System.out.println("I like lambda");
}
}二、Test2
package com.kuang.lambda;
public class TestLambda2 {
public static void main(String[] args) {
ILove love = null;
//1、lambda表示简化
love = (int a,int b)->{
System.out.println("i love you-->"+a);
};
//2、简化2.简化括号
love = (a,b) ->{
System.out.println("i love you -->"+a);
System.out.println("i love you too");
};
love = ((a, b) -> System.out.println("i love you"));
love.love(520,502);
/*
* 总结：
* 1、lambda表达式只能有一行代码的情况下才能简化为一行，如果有多行，那么就用代码块包裹
* 2、前提是接口为函数式接口
* 3、多个参数也可以去掉参数类型，要去掉就都去掉，必须加上括号
* */
}
}
interface ILove{
void love(int a,int b);
}