JAVA复习之线程

一、线程

二、线程的特点

三、线程的生命周期

四、Thread类

Thread类是java.lang包中的一个类，Thread类的对象用来代表线程，通过继承Thread类创建、启动并执行一个线程的步骤：①创建一个继承Thread类的子类；②覆写Thread类的run()方法；③创建线程类的一个对象；④通过线程类的对象调用start()方法启动线程(启动之后会自动调用覆写的run()方法执行线程)。

案例分析：

public class Demo5 { public static void main(String[] args) { ThreadA threadA = new ThreadA(); threadA.start(); ThreadB threadB = new ThreadB(); threadB.start(); } } class ThreadA extends Thread{ public void run(){ for(int i=0;i<100;i++){ System.out.println(i); try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } } } } class ThreadB extends Thread{ public void run(){ for(char i= 'a';i<'z';i++){ System.out.println(i); try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } } } }

五、Runnable接口

六、线程的休眠

七、线程的加入

八、线程的中断

九、线程的安全

（一）案例之线程不安全，出现脏读

public class Demo6 implements Runnable{ int num = 10; public static void main(String[] args) { Demo6 demo = new Demo6(); Thread t1 = new Thread(demo,"线程一"); Thread t2 = new Thread(demo,"线程二"); Thread t3 = new Thread(demo,"线程三"); Thread t4 = new Thread(demo,"线程四"); t1.start(); t2.start(); t3.start(); t4.start(); } @Override public void run() { while (true){ if(num>0){ System.out.println("票数："+num--); try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } } } } }

（二）线程同步机制synchronized关键字

两种方法： 案例剖析：

public class Demo6 implements Runnable{ int num = 10; public static void main(String[] args) { Demo6 demo = new Demo6(); Thread t1 = new Thread(demo,"线程一"); Thread t2 = new Thread(demo,"线程二"); Thread t3 = new Thread(demo,"线程三"); Thread t4 = new Thread(demo,"线程四"); t1.start(); t2.start(); t3.start(); t4.start(); } @Override public void run() { while (true){ synchronized (this){ if(num>0){ System.out.println("票数："+num--); try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } } } } } }