java多線程學習之-3個線程交替運作5次，分别列印其線程名字

@JAVA多線程學習之-3個線程分别列印ABC交替5次

1. 使用Lock-Condition 實作。定義一個value 來控制哪個線程工作。因為是用if 判斷的，i++操作必須要在正确列印之後自己去控制i++，不可放在for循環力裡面

class Resource1 {
    private volatile int value = 1;
    private ReentrantLock lock = new ReentrantLock();
    Condition condition1 = lock.newCondition();
    /**
     * 線程A
     */
    void printA() {
        try {
            lock.lock();
            for (int i = 0; i < 5; ) {
                if (value == 1) {
                    System.out.print(Thread.currentThread().getName());
                    value = 2;
                    i++;
                    condition1.signalAll();
                } else {
                    condition1.await();
                }
            }

        } catch (InterruptedException e) {

        } finally {
            lock.unlock();
        }
    }

    /**
     * 線程B
     */
    void printB() {
        try {
            lock.lock();
            for (int i = 0; i < 5;) {
                if (value == 2) {
                    System.out.print(Thread.currentThread().getName());
                    value = 3;
                    i++;
                    condition1.signalAll();
                } else {
                    condition1.await();
                }
            }

        } catch (InterruptedException e) {
            e.printStackTrace();
        } finally {
            lock.unlock();
        }
    }

    /**
     * 線程C
     */
    void printC() {
        try {
            lock.lock();
            for (int i = 0; i < 5; ) {
                if (value == 3) {
                    System.out.print(Thread.currentThread().getName());
                    value = 1;
                    i++;
                    condition1.signalAll();
                } else {
                    condition1.await();
                }
            }

        } catch (InterruptedException e) {
            e.printStackTrace();
        } finally {
            lock.unlock();
        }
    }
}


    public static void main(String[] args) {
        Resource1 resource1 = new Resource1();
        new Thread(()->resource1.printA(),"A").start();
        new Thread(()->resource1.printB(),"B").start();
        new Thread(()->resource1.printC(),"C").start();
    }

輸出結果：ABCABCABCABCABC
           

##使用 wait- notify實作，列印次數在外面控制，裡面用while判斷是哪個線程工作

class Resource3 {
    private volatile int value = 1;

    /**
     * 線程A
     */
    void printA() {
        synchronized (this) {
            while (value != 1) {
                try {
                    wait();
                } catch (Exception e) {
                }
            }

            System.out.print(Thread.currentThread().getName());
            value = 2;
            notifyAll();
        }

    }

    /**
     * 線程B
     */
    void printB() {
        synchronized (this) {
            while (value != 2) {
                try {
                    wait();
                } catch (Exception e) {
                }
            }

            System.out.print(Thread.currentThread().getName());
            value = 3;
            notifyAll();
        }
    }

    /**
     * 線程C
     */
    void printC() {
        synchronized (this) {
            while (value != 3) {
                try {
                    wait();
                } catch (Exception e) {
                }
            }

            System.out.print(Thread.currentThread().getName());
            value = 1;
            notifyAll();
        }
    }
}

public static void main(String[] args) {
        Resource3 resource1 = new Resource3();
      /*  new Thread(()->resource1.printA(),"A").start();
        new Thread(()->resource1.printB(),"B").start();
        new Thread(()->resource1.printC(),"C").start();*/

        new Thread(() -> {
            for (int i = 0; i < 5; i++) {
                resource1.printA();
            }
        }, "A").start();
        new Thread(() -> {
            for (int i = 0; i < 5; i++) {
                resource1.printB();
            }
        }, "B").start();

        new Thread(() -> {
            for (int i = 0; i < 5; i++) {
                resource1.printC();
            }
        }, "C").start();
    }