#千锋逆战班#

最新推荐文章于 2020-03-17 22:28:57 发布

原创最新推荐文章于 2020-03-17 22:28:57 发布 · 193 阅读

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在千锋学习的第二十八天

加倍努力！

今天学习了线程，分别就线程的创建和线程的安全

习题

1一个cpu 的机器，执行的任务每个执行一段时间。线程呈现并发执行

package com.lichenchen.xiti;

public class TestDemo1 {

	public static void main(String[] args) {
		Example ex1 =new Example();
		Example ex2 =new Example();
		Example ex3 =new Example();
		ex1.run();
		ex2.run();
		ex3.run();

	}

}
class Example implements Runnable{
	public void run(){
		while(true){}
	}
}

选择正确答案
C  代码编译成功，存在一个可运行的线程

package com.lichenchen.xiti;

 class Example1  implements Runnable{

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Thread t = new Thread(new Example());
		t.start();

	}
	public void run(int limit){
		for(int i =0;i<limit;i++){
			System.out.println(i);
		}
	}
	

}

C 代码编译失败，因为没有正确实现Runnable 接口

package com.lichenchen.xiti;

public class Example2 {
  public static void main(String[] args) {
	//Thread.sleep(3000);
	System.out.println("sleep");
}
}
 编译出错

package com.lichenchen.xiti;

import java.util.Random;

public class TestDemo4 {

	public static void main(String[] args) {
		MyThread t =new MyThread();
		t.start();
		MyThread2 t1 =new MyThread2();
		Thread th =new Thread(t1);
		th.start();
	}

}
class MyThread extends Thread{

	public void run(){
		Random r =new Random();
		for(int i =1;i<=100;i++){
			System.out.println(r.nextInt(26)+"\t    -/"+i);
		}
		
	}
	
}
class MyThread2 implements Runnable{

	@Override
	public void run() {
	
			for(int c =1;c<=100;c++){
				Random  r1 =new Random();
				int ran =r1.nextInt(26);
				Character ac =(char)(ran+65);
				System.out.println(ac+"\t"+c);
			}
		
		
	}
	
}

package com.lichenchen.xiti;

public class TestMyThread {

	public static void main(String[] args) {
		Object lock =new Object();
		Thread t1 =new MyThread3(lock);
		Thread t2 =new MyThread4(lock);
		t1.start();
		t2.start();
		
	}

}
class MyThread3 extends Thread{
	Object lock;

	public MyThread3(Object lock) {
		super();
		this.lock = lock;
	}
	public void run(){
		//synchronized(lock){
			for(int i =0;i<=10;i++){
				try{
					Thread.sleep((int)(Math.random()*1000));
					System.out.println("程序技术");
				}catch (Exception e){
					System.out.println("$$$");
				}
				
			//}
		}
	}
}
class MyThread4 extends Thread{
	Object lock;

	public MyThread4(Object lock) {
		super();
		this.lock = lock;
	}
	public void run(){
		//synchronized (lock) {//2
			for(int i=0;i<=10;i++){
				try{
					Thread.sleep((int)(Math.random()*1000));
					System.out.println("我也休眠啦");
				}catch(Exception e){
					
				}
				System.out.println("####");
				
			//}
		}
	}
}

在加入synchronized 同步 只能以一个线程访问内部代码 
如果不加 线程会交替执行

package com.lichenchen.xiti;

public class TestMyThreads {

	public static void main(String[] args) {
		Thread t1 =new MyThreadsd("hello");
		Thread t2 =new MyThreadsd("world");
		t1.start();
		t2.start();
		

	}

}
class MyThreadsd extends Thread{
	private String data;
	
	public MyThreadsd(String data) {
		super();
		this.data = data;
	}

	public void run(){
		synchronized (data) {
			for(int i =0;i<10;i++){
				try{
					Thread.sleep((int)(Math.random()*1000));
				}catch(Exception e){
					
				}
				System.out.println(data);
			}
		}
	}
}
C 线程不同步 所以交替输出hello 和word