Java多线程基础(面试向)

public class ThreadTest04 {

    public static void main(String[] args) {
        Runnable runnable = new Processor();
        Thread thread_1 = new Thread(runnable,"r1");
        thread_1.start();
        Thread thread_2 = new Thread(runnable,"r2");
        thread_2.start();
    }

}

class Processor implements Runnable{

    @Override
    public void run() {
        for(int i=0; i<100; i++){
         System.out.println(Thread.currentThread().getName() + "," + i);
         
         if(i%10 == 0){
             try {
              //睡眠100毫秒，将CPU时间片交给其他线程使用
                Thread.sleep(100);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
         }
        }        
    }    
}

public class ThreadTest05 {
    
       public static void main(String[] args) {  
            System.out.println(Thread.currentThread().getName()+"主线程运行开始!");  
            Thread1 mTh1=new Thread1("A");  
            Thread1 mTh2=new Thread1("B");  
            mTh1.start();  
            mTh2.start();  
            try {
                mTh1.join();
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            try {
                mTh2.join();
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            System.out.println(Thread.currentThread().getName()+ "主线程运行结束!");  
      
        }  

}
class Thread1 extends Thread{  
    private String name;  
    public Thread1(String name) {  
        super(name);  
       this.name=name;  
    }  
    public void run() {  
        System.out.println(Thread.currentThread().getName() + " 线程运行开始!");  
        for (int i = 0; i < 5; i++) {  
            System.out.println("子线程"+name + "运行 : " + i);  
            try {  
                sleep((int) Math.random() * 10);  
            } catch (InterruptedException e) {  
                e.printStackTrace();  
            }  
        }  
        System.out.println(Thread.currentThread().getName() + " 线程运行结束!");  
    }  
}  

main主线程运行开始!
B 线程运行开始!
A 线程运行开始!
子线程B运行 : 0
子线程A运行 : 0
子线程B运行 : 1
子线程A运行 : 1
子线程B运行 : 2
子线程A运行 : 2
子线程B运行 : 3
子线程A运行 : 3
子线程B运行 : 4
子线程A运行 : 4
B 线程运行结束!
A 线程运行结束!
main主线程运行结束!

public class ThreadTest06 {

    public static void main(String[] args) {
        MyThread_2 yt1 = new MyThread_2("张三");  
        MyThread_2 yt2 = new MyThread_2("李四");  
        yt1.start();  
        yt2.start();  
    }

}

class MyThread_2 extends Thread{
    
    MyThread_2(String s){
        super(s);
    }
    @Override
    public void run() {
        for(int i=0; i<=50; i++){
            System.out.println(Thread.currentThread().getName()+":"+i);
            if(i==30){
          // 当i为30时，该线程就会把CPU时间让掉，让其他或者自己的线程执行（也就是谁先抢到谁执行）  
                this.yield();
            }
        }
    }
}

package com.xxg.thread;

public class ThreadTest07 {

    public static void main(String[] args) {
        new Thread(new Thread01()).start();
        try {
            Thread.sleep(5000);
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        new Thread(new Thread02()).start();
    }

}

class Thread01 implements Runnable {

    @Override
    public void run() {
        synchronized (ThreadTest07.class) {
            System.out.println("enter thread1...");
            System.out.println("thread1 is waiting...");

            try {
                // 调用wait()方法，线程会放弃对象锁，进入等待此对象的等待锁定池
                ThreadTest07.class.wait();
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            System.out.println("thread1 is going on ....");
            System.out.println("thread1 is over!!!");
        }
    }
}

class Thread02 implements Runnable {

    @Override
    public void run() {
        synchronized (ThreadTest07.class) {
            System.out.println("enter thread2...");
            System.out.println("thread2 is sleeping...");
            // 只有针对此对象调用notify()方法后本线程才进入对象锁定池准备获取对象锁进入运行状态。
            ThreadTest07.class.notify();

            // 区别
            // 如果我们把代码：TestD.class.notify();给注释掉，即TestD.class调用了wait()方法，但是没有调用notify()
            // 方法，则线程永远处于挂起状态。
            try {
                // sleep()方法导致了程序暂停执行指定的时间，让出cpu该其他线程，
                // 但是他的监控状态依然保持者，当指定的时间到了又会自动恢复运行状态。
                // 在调用sleep()方法的过程中，线程不会释放对象锁。
                Thread.sleep(5000);
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            System.out.println("thread2 is going on ....");
            System.out.println("thread2 is over!!!");
        }
    }
}