关于JAVA线程面试题

关于JAVA线程面试题

1.doOther需要等到doSome结束吗

package javase.exam1;
/**
 * 面试题：doOther需要等到doSome结束吗
 *   不需要 
 *     synchronized 作用在实例方法上 相当于this 而doother没有synchronized
 *  
 * @author yumu
 *
 */
public class Exam01 {

    public static void main(String[] args) throws InterruptedException {
        MyClass mc=new MyClass();
        
        Thread t1=new MyThread(mc);
        Thread t2=new MyThread(mc);
        t1.setName("t1");
        t2.setName("t2");
        
        t1.start();
        Thread.sleep(1000);
        t2.start();
    }

}
class MyThread extends Thread{
    private MyClass mc;
    public MyThread(MyClass mc){
        this.mc=mc;
    }
    public void run(){
        if(Thread.currentThread().getName().equals("t1")){
            mc.doSome();
            
        }
        if(Thread.currentThread().getName().equals("t2")){
            mc.doOther();
            
        }
        
    }
}
class MyClass{
//    public synchronized static void doSome(){   synchronized出现在静态方法上,是类锁,只有一把,需要等待
    public synchronized void doSome(){
        System.out.println("doSome begin");
        try {
            Thread.sleep(1000*10);
        } catch (InterruptedException e) {
            
            e.printStackTrace();
        }
        System.out.println("doSome over");
    }
    public void doOther(){
        System.out.println("doother begin");
        
        System.out.println("doother over");
    }
}

2.doOther需要等到doSome结束吗

package javase.exam1;
/**
 * 面试题：doOther需要等到doSome结束吗
 *   不需要 
 *   myclass对象两个 两把锁  
 *  
 * @author yumu
 *
 */
public class Exam02 {

    public static void main(String[] args) throws InterruptedException {
        MyClass mc1=new MyClass();
        MyClass mc2=new MyClass();
        
        Thread t1=new MyThread1(mc1);
        Thread t2=new MyThread1(mc2);
        t1.setName("t1");
        t2.setName("t2");
        
        t1.start();
        Thread.sleep(1000);
        t2.start();
    }

}
class MyThread1 extends Thread{
    private MyClass mc;
    public MyThread1(MyClass mc){
        this.mc=mc;
    }
    public void run(){
        if(Thread.currentThread().getName().equals("t1")){
            mc.doSome();
            
        }
        if(Thread.currentThread().getName().equals("t2")){
            mc.doOther();
            
        }
        
    }
}
class MyClass1{
    public synchronized void doSome(){
        System.out.println("doSome begin");
        try {
            Thread.sleep(1000*10);
        } catch (InterruptedException e) {
            
            e.printStackTrace();
        }
        System.out.println("doSome over");
    }
    public synchronized void doOther(){
        System.out.println("doother begin");
        
        System.out.println("doother over");
    }
}

3.关于Thread.sleep()方法 线程t会进入休眠吗

package javase.thread;
/**
 * 关于Thread.sleep()方法面试题
 *   线程t会进入休眠吗
 * @author yumu
 *
 */
public class ThreadTest06 {

    public static void main(String[] args) throws InterruptedException {
        MyThread3 t=new MyThread3();
        t.setName("t2");
        t.start();
        //调用sleep    静态方法
        t.sleep(2000);  //在执行的时候还是会转换成Thread.sleep(2000);
                        //这换代码是让当前线程进入休眠,他出现在main方法
        System.out.println("你好");//2秒后输出
    }

}
class MyThread3 extends Thread{
    public void run(){
        for(int i=0;i<10;i++){
            System.out.println(Thread.currentThread().getName()+"--->"+i);
        }
    }
}

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