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

 1 package javase.exam1;
 2 /**
 3  * 面试题：doOther需要等到doSome结束吗
 4  *   不需要 
 5  *     synchronized 作用在实例方法上 相当于this 而doother没有synchronized
 6  *  
 7  * @author yumu
 8  *
 9  */
10 public class Exam01 {
11 
12     public static void main(String[] args) throws InterruptedException {
13         MyClass mc=new MyClass();
14         
15         Thread t1=new MyThread(mc);
16         Thread t2=new MyThread(mc);
17         t1.setName("t1");
18         t2.setName("t2");
19         
20         t1.start();
21         Thread.sleep(1000);
22         t2.start();
23     }
24 
25 }
26 class MyThread extends Thread{
27     private MyClass mc;
28     public MyThread(MyClass mc){
29         this.mc=mc;
30     }
31     public void run(){
32         if(Thread.currentThread().getName().equals("t1")){
33             mc.doSome();
34             
35         }
36         if(Thread.currentThread().getName().equals("t2")){
37             mc.doOther();
38             
39         }
40         
41     }
42 }
43 class MyClass{
44 //    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
45     public synchronized void doSome(){
46         System.out.println("doSome begin");
47         try {
48             Thread.sleep(1000*10);
49         } catch (InterruptedException e) {
50             
51             e.printStackTrace();
52         }
53         System.out.println("doSome over");
54     }
55     public void doOther(){
56         System.out.println("doother begin");
57         
58         System.out.println("doother over");
59     }
60 }

2.doOther需要等到doSome结束吗

 1 package javase.exam1;
 2 /**
 3  * 面试题：doOther需要等到doSome结束吗
 4  *   不需要 
 5  *   myclass对象两个 两把锁  
 6  *  
 7  * @author yumu
 8  *
 9  */
10 public class Exam02 {
11 
12     public static void main(String[] args) throws InterruptedException {
13         MyClass mc1=new MyClass();
14         MyClass mc2=new MyClass();
15         
16         Thread t1=new MyThread1(mc1);
17         Thread t2=new MyThread1(mc2);
18         t1.setName("t1");
19         t2.setName("t2");
20         
21         t1.start();
22         Thread.sleep(1000);
23         t2.start();
24     }
25 
26 }
27 class MyThread1 extends Thread{
28     private MyClass mc;
29     public MyThread1(MyClass mc){
30         this.mc=mc;
31     }
32     public void run(){
33         if(Thread.currentThread().getName().equals("t1")){
34             mc.doSome();
35             
36         }
37         if(Thread.currentThread().getName().equals("t2")){
38             mc.doOther();
39             
40         }
41         
42     }
43 }
44 class MyClass1{
45     public synchronized void doSome(){
46         System.out.println("doSome begin");
47         try {
48             Thread.sleep(1000*10);
49         } catch (InterruptedException e) {
50             
51             e.printStackTrace();
52         }
53         System.out.println("doSome over");
54     }
55     public synchronized void doOther(){
56         System.out.println("doother begin");
57         
58         System.out.println("doother over");
59     }
60 }

3.关于Thread.sleep()方法 线程t会进入休眠吗

 1 package javase.thread;
 2 /**
 3  * 关于Thread.sleep()方法面试题
 4  *   线程t会进入休眠吗
 5  * @author yumu
 6  *
 7  */
 8 public class ThreadTest06 {
 9 
10     public static void main(String[] args) throws InterruptedException {
11         MyThread3 t=new MyThread3();
12         t.setName("t2");
13         t.start();
14         //调用sleep    静态方法
15         t.sleep(2000);  //在执行的时候还是会转换成Thread.sleep(2000);
16                         //这换代码是让当前线程进入休眠,他出现在main方法
17         System.out.println("你好");//2秒后输出
18     }
19 
20 }
21 class MyThread3 extends Thread{
22     public void run(){
23         for(int i=0;i<10;i++){
24             System.out.println(Thread.currentThread().getName()+"--->"+i);
25         }
26     }
27 }

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