代碼都已上傳github

P02 使用三個(gè)線程使得ABC 循環(huán)輸出十次

心得

• 利用Condition 來(lái)控制對(duì)哪個(gè)類(lèi)型的鎖進(jìn)行釋放醇蝴。可以達(dá)到對(duì)3個(gè)線程的一個(gè)控制导坟。
• 對(duì)于線程輸出的控制順序缠诅，可以加入一個(gè)判斷順序Int.來(lái)決定是否輪到該線程運(yùn)行，不是則繼續(xù)等待乍迄。

代碼塊

public class P02 {
    private static ReentrantLock lock;
    public static int ThSum=1; //決定那個(gè)線程運(yùn)行


    /*使用三個(gè)線程使得ABC 循環(huán)輸出十次*/
    public static void po2(){
        lock = new ReentrantLock(true);

        Thread t1 = new Thread(new t1(lock));
        Thread t2 = new Thread(new t2(lock));
        Thread t3 = new Thread(new t3(lock));
        t1.start();
        t2.start();
        t3.start();
    }


}

class t1 implements Runnable{

    private ReentrantLock lock;
    public static Condition conditionA;

    public t1(ReentrantLock lock) {
        this.lock = lock;
        conditionA = lock.newCondition();
    }

    @Override
    public void run() {
        try {
            for (int i = 1; i <= 10; i++) {
                lock.lock();
                while (P02.ThSum != 1) {    //如果沒(méi)有該判斷順序管引，則線程1 可能會(huì)再次獲得鎖。不能確保順序正確
                    conditionA.await();    //當(dāng)還不是該線程輸出的時(shí)候闯两，釋放鎖
                }
                System.out.print("第"+i+"次");
                System.out.print('A');
                P02.ThSum = 2;
                t2.conditionB.signalAll(); //釋放第二個(gè)線程 喚醒第二個(gè)線程
                lock.unlock();             //釋放鎖褥伴，是因?yàn)樽詈笠淮蔚臅r(shí)候谅将，如果沒(méi)有釋放鎖，那么2 3 線程并不能獲取到鎖重慢。
            }
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

    }
}

class t2 implements Runnable{

    private ReentrantLock lock;
    public static Condition conditionB;


    public t2(ReentrantLock lock) {
        this.lock = lock;
        conditionB = lock.newCondition();
    }

    @Override
    public void run() {
        try {
            for (int i = 0; i < 10; i++) {
                lock.lock();
                while (P02.ThSum != 2) {
                    conditionB.await();
                }
                System.out.print('B');
                P02.ThSum = 3;
                t3.conditionC.signalAll();
                lock.unlock();
            }

        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

class t3 implements Runnable{

    private ReentrantLock lock;
    public static Condition conditionC;

    public t3(ReentrantLock lock) {
        this.lock = lock;
        conditionC = lock.newCondition();
    }

    @Override
    public void run() {
        try {
            for (int i = 0; i < 10; i++) {
                lock.lock();
                while (P02.ThSum != 3) {
                    conditionC.await();
                }
                System.out.println('C');
                P02.ThSum = 1;
                t1.conditionA.signalAll();

            }
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

輸出效果

image.png