线程

线程

线程实现方法：Thread类，继承Runnable接口。但是Runnable需要用Thread实例。

      优先级

<span style="font-size:14px;">class RunnableTest implements Runnable{public void run() {// TODO Auto-generated method stubfor(int j=0;j<5;j++){try {Thread.sleep(1000);System.out.print(Thread.currentThread().getName()+":"+j+"  ");} catch (InterruptedException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}}public class RunnableDome {public static void main(String[] args) {// TODO Auto-generated method stubThread t1=new Thread(new RunnableTest(),"A");Thread t2=new Thread(new RunnableTest(),"B");Thread t3=new Thread(new RunnableTest(),"c");//设置优先级t1.setPriority(Thread.MIN_PRIORITY);t2.setPriority(Thread.MAX_PRIORITY);t3.setPriority(Thread.NORM_PRIORITY);t1.start();t2.start();t3.start();}}</span>

线程常用方法

<span style="font-size:14px;">public class ThreadDemo extends Thread{String name;public ThreadDemo(String name){this.name=name;}//必须重写run()方法，把功能代码放入public void run(){System.out.println("返回当前线程的线程组中活动线程的数目:"+Thread.activeCount());System.out.println("返回对当前正在执行的线程对象的引用:"+Thread.currentThread());System.out.println("返回该线程的名称:"+Thread.currentThread().getName());for(int j=0;j<10;j++){if(j>5&&j<8){//暂停当前正在执行的线程对象，并执行其他线程yield();System.out.println(name+":"+j);}else if(j>8){try {//join()等待该线程终止join();System.out.println("name:"+j);} catch (InterruptedException e) {// TODO Auto-generated catch blocke.printStackTrace();}}else{try {//sleep()方法是指定的毫秒数内让当前正在执行的线程休眠。sleep(1000);System.out.println(name+":"+j);} catch (InterruptedException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}}public static void main(String[] args) {// TODO Auto-generated method stub//创建线程ThreadDemo t1=new ThreadDemo("A");ThreadDemo t2=new ThreadDemo("B");//启动线程方法start()方法。几个线程时，谁抢到资源谁先执行t1.start();t2.start();System.out.println("测试线程是否处于活动状态:"+Thread.currentThread().isAlive());}}</span>

线程的同步机制synchronized

1.同步代码块

synchronized(同步对象){

需要同步的代码

}

<span style="font-size:14px;">class Test implements Runnable{        //定义车票数量，好为下面进行判断private int ticket=10;public void run() {// TODO Auto-generated method stubfor(int j=1;j<11;j++){synchronized(this){if(ticket>0){try {Thread.sleep(500);} catch (InterruptedException e) {// TODO Auto-generated catch blocke.printStackTrace();}System.out.println("车票:"+ticket--);}}}}}public class Synchronized01 {public static void main(String[] args) {// TODO Auto-generated method stub<span style="color:#FF0000;">//三个窗口同时卖10张票，这时候，实例对象，Thread线程的对象必须是同一个</span>Test t=new Test();Thread t1=new Thread(t);Thread t2=new Thread(t);Thread t3=new Thread(t);t1.start();t2.start();t3.start();}}</span>

2.同步方法

synchronized  void  方法名(){

}

class Test implements Runnable{private int ticket=10;public void run() {// TODO Auto-generated method stubfor(int j=1;j<11;j++){tell();}}synchronized void tell(){if(ticket>0){try {Thread.sleep(500);} catch (InterruptedException e) {// TODO Auto-generated catch blocke.printStackTrace();}System.out.println("车票:"+ticket--);}}}public class Synchronized01 {public static void main(String[] args) {// TODO Auto-generated method stub//三个窗口同时卖10张票Test t=new Test();Thread t1=new Thread(t);Thread t2=new Thread(t);Thread t3=new Thread(t);t1.start();t2.start();t3.start();}}

效果和同步代码块一样