java线程join()方法分析

我会带着你远行 2022-08-11 15:30 170阅读 0赞

join()方法作用就是：当一个线程中调用另一个线程的join()方法时，当前线程会等待另一个线程执行完毕后，在继续执行。起到一种同步的作用。即：若线程A调用线程B的join()方法，那么A会等到B的run()中内容执行完毕再去执行A的run 方法。

package com.zhiru;
    
    class TA implements Runnable {
    
    	private int count = 0;
    
    	@Override
    	public void run() {
    		//启动线程TA
    		System.out.println(Thread.currentThread().getName()+"start...");
    		while (count <= 10) {
    			System.out.print("count=" + count + " ");
    			count++;
    		}
    		System.out.print("\n");
    	}
    
    }
    
    class TB implements Runnable {
    
    	private int id = 0;
    
    	private Thread c;
    	@Override
    	public void run() {
    		// TODO Auto-generated method stub
    		System.out.println(Thread.currentThread().getName()+"start...");
    		c=new Thread(new TC());//创建线程TC的对象
    		try {
    			c.start();
    			c.join();//加入线程TC,直到线程TC中的run内容执行完在执行TB的。
    		} catch (InterruptedException e) {
    			// TODO Auto-generated catch block
    			e.printStackTrace();
    		}
    		while (id++ <= 10) {
    			System.out.print("id=" + id + " ");
    		}
    		System.out.print("\n");
    	}
    
    }
    class TC implements Runnable{
    
    	@Override
    	public void run() {
    		// TODO Auto-generated method stub
    		System.out.println("TC was called!"+Thread.currentThread().getName()+"start...");
    		for(int i=1;i<=10;i++) System.out.print(i+" ");
    		System.out.print("\n");
    	}
    	
    }
    public class ThreadJoin {
    
    	public static void main(String[] args) throws InterruptedException {
    		// TODO Auto-generated method stub
    		Thread t2=new Thread(new TB());
    		Thread t1=new Thread(new TA());
    		t2.start();
    		t2.join();//直到线程t2执行完在执行t1.
    		t1.start();
    //		t1.join();
    	}
    
    }

Thread-0start...  
TC was called!Thread-2start...  
1 2 3 4 5 6 7 8 9 10   
id=1 id=2 id=3 id=4 id=5 id=6 id=7 id=8 id=9 id=10 id=11   
Thread-1start...  
count=0 count=1 count=2 count=3 count=4 count=5 count=6 count=7 count=8 count=9 count=10