java多線程編程（打印三個線程名5次ABCABCABCABCABC）

1.題目描述

啓動三個線程，三個線程名稱分別是A,B,C；每個線程將自己的名稱在屏幕上打印5遍，打印順序是ABCABCABCABCABC

2.解題思路

2.1寫打印A、B、C的方法

//設置標記位，判斷應該打印哪個線程名
    private int flag = 1;
//記錄打印次數
    private int count = 1；
//打印線程名稱A方法
//    順序打印，用鎖
    public synchronized void PrintA(){
//    如果falg不爲1，等待
        while (flag != 1){
            try {
                wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
//    打印當前線程名
        System.out.print(Thread.currentThread().getName());
//    使其可以進入打印線程B方法
        flag = 2;
        notifyAll();
//    打印次數+1
        count++;
    }
//打印線程名稱B方法
    public synchronized void PrintB(){
        while (flag != 2){
            try {
                wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        System.out.print(Thread.currentThread().getName());
        flag = 3;
        notifyAll();
        count++;
    }
//打印線程名稱C方法
    public synchronized void PrintC(){
        while (flag != 3){
            try {
                wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        System.out.print(Thread.currentThread().getName());
        flag = 1;
        notifyAll();
        count++;
    }

2.2寫MyThread類調用三個打印方法

class MyThread implements Runnable{
    public PrintTest1 printTest1;
    public MyThread(PrintTest1 printTest1){
        this.printTest1 = printTest1;
    }
    @Override
    public void run() {
//    因爲最後一次打印A時count=13
        while(printTest1.getCount()<14){
            if(Thread.currentThread().getName().equals("A")){
                printTest1.PrintA();
            }
            if(Thread.currentThread().getName().equals("B")){
                printTest1.PrintB();
            }
            if(Thread.currentThread().getName().equals("C")){
                printTest1.PrintC();
            }
        }
    }
}

3.整體代碼如下

/**
 * 2.啓動三個線程，三個線程名稱分別是A,B,C；
 * 每個線程將自己的名稱在屏幕上打印5遍，打印順序是ABCABCABCABCABC
 */
class PrintTest1{
    private int flag=1;
    private int count=1;
    public int getCount(){
        return count;
    }
    public synchronized void PrintA(){
        while (flag != 1){
            try {
                wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        System.out.print(Thread.currentThread().getName());
        flag = 2;
        notifyAll();
        count++;
    }
    public synchronized void PrintB(){
        while (flag != 2){
            try {
                wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        System.out.print(Thread.currentThread().getName());
        flag = 3;
        notifyAll();
        count++;
    }
    public synchronized void PrintC(){
        while (flag != 3){
            try {
                wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        System.out.print(Thread.currentThread().getName());
        flag = 1;
        notifyAll();
        count++;
    }

}

class MyThread implements Runnable{
    public PrintTest1 printTest1;
    public MyThread(PrintTest1 printTest1){
        this.printTest1 = printTest1;
    }
    @Override
    public void run() {
        while(printTest1.getCount()<14){
            if(Thread.currentThread().getName().equals("A")){
                printTest1.PrintA();
            }
            if(Thread.currentThread().getName().equals("B")){
                printTest1.PrintB();
            }
            if(Thread.currentThread().getName().equals("C")){
                printTest1.PrintC();
            }
        }
    }
}
public class Test2 {
    public static void main(String[] args) {
        PrintTest1 printTest1 = new PrintTest1();
        MyThread myThread = new MyThread(printTest1);
        new Thread(myThread,"A").start();
        new Thread(myThread,"B").start();
        new Thread(myThread,"C").start();
    }
}

4.運行結果