第一種方式:Lock鎖

package com.test;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
public class ThreadDemo {
    private static int state=0;
    public static void main(String[] args) {
        final Lock lock=new ReentrantLock();

        Thread A=new Thread(new Runnable(){
            public void run(){

                while(state<=27){
                    lock.lock();
                    if(state%3==0){
                        System.out.println("我");
                        state ++;
                    }
                    lock.unlock();
                }
            }
        });

        Thread B=new Thread(new Runnable(){
            public void run(){

                while(state<=27){
                    lock.lock();
                    if(state%3==1){
                        System.out.println("愛");
                        state ++;
                    }
                    lock.unlock();
                }
            }
        });

        Thread C=new Thread(new Runnable(){
            public void run(){

                while(state<=27){
                    lock.lock();
                    if(state%3==2){
                        System.out.println("你");
                        state ++;
                    }
                    lock.unlock();
                }
            }
        });

        A.start();
        B.start();
        C.start();

    }

}
運行結果如下:

第二種:synchronized同步方法:

具體代碼如下:

package com.test;
public class ThreadDemo2 implements Runnable{
    
    
    //三個變量 三條線程之間切換執行 一把鎖是不夠的  2把鎖把鎖  對象有鎖的定義 Object對象

    private String word;//線程要打印的字
    private Object prev;//當前線程的上一個線程要持有的鎖
    private Object current;//當前線程所要持有的鎖

    public void run() {
        for(int i=0;i<10;i++){
            synchronized (prev){
                synchronized (current){
                    System.out.println(word);
                    current.notify();
                }
                try {
                    prev.wait();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    public ThreadDemo2(String word, Object prev, Object current) {
        this.word = word;
        this.prev = prev;
        this.current = current;
    }
    //打印字的操作
}


測試類:

package com.test;

public class TestThreadDemo2 { 
    public static void main(String[]args) throws Exception{
       Object a=new Object();
       Object b=new Object();
       Object c=new Object();
       Thread t1=new Thread(new ThreadDemo2("I",c,a));
       Thread t2=new Thread(new ThreadDemo2("love",a,b));
       Thread t3=new Thread(new ThreadDemo2("you",b,c));
       t1.start();;
       Thread.sleep(1000);
       t2.start();;
       Thread.sleep(1000);
       t3.start();
    }
}

運行結果:

多線程--打印十次"我愛你"