认识达内从这里开始

昆明IT培训的小编知道，Condition接口描述了可能会与锁有关联的条件变量。这些变量在用法与使用Object.wait访问的隐式监视器类似，但提供了更强大的功能。需要特别指出的是，单个Lock可能与多个Condition对象关联。为了避免兼容性问题，Condition方法的名称与对应的Object版本中的不同；

在Condition对象中，与wait、notify和notifyAll方法对应的分别是await、signal和signalAll；

Condition实例实质上被绑定到一个锁上。要为特定Lock实例获得Condition实例，请使用器newCondition()方法。

1 package com.ccfdod.juc;

2

3 import java.util.concurrent.locks.Condition;

4 import java.util.concurrent.locks.Lock;

5 import java.util.concurrent.locks.ReentrantLock;

6

7 /**

8 *题目：编写一个程序，开启3个线程，这三个线程的ID分别为A、B、C，每个线程将自己的ID在屏幕上打印10遍，要求输出的结果必须按顺序显示。

9 *如：ABCABCABC……

10 */

11 class AlternateDemo {

12    //标志当前由哪一个线程输出，1代表A，2代表B，3代表C

13    private int number = 1;

14

15    Lock lock = new ReentrantLock();

16

17    //Condition的强大之处在于它可以为多个线程间建立不同的Condition

18    Condition condition1 = lock.newCondition();

19    Condition condition2 = lock.newCondition();

20    Condition condition3 = lock.newCondition();

21

22    // loopNum:当前循环轮数

23    public void loopA(int loopNum) {

24        //上锁

25        lock.lock();

26        try {

27            while (number != 1) {

28                //等待

29                condition1.await();

30            }

31

32            System.out.println(Thread.currentThread().getName() + ", currentLoopNum is " + loopNum);

33            number = 2;

34            //唤醒

35            condition2.signal();

36

37        } catch (InterruptedException e) {

38            e.printStackTrace();

39        } finally {

40            //确保释放锁

41            lock.unlock();

42        }

43    }

44

45    public void loopB(int loopNum) {

46        lock.lock();

47        try {

48            while (number != 2) {

49                condition2.await();

50            }

51

52            System.out.println(Thread.currentThread().getName() + ", currentLoopNum is " + loopNum);

53            number = 3;

54            condition3.signal();

55

56        } catch (InterruptedException e) {

57            e.printStackTrace();

58        } finally {

59            lock.unlock();

60        }

61    }

62

63    public void loopC(int loopNum) {

64        lock.lock();

65        try {

66            while (number != 3) {

67                condition3.await();

68            }

69

70            System.out.println(Thread.currentThread().getName() + ", currentLoopNum is " + loopNum);

71            number = 1;

72            condition1.signal();

73

74        } catch (InterruptedException e) {

75            e.printStackTrace();

76        } finally {

77            lock.unlock();

78        }

79    }

80 }

81

82 public class TestABCAlternate {

83

84    public static void main(String[] args) {

85        AlternateDemo ad = new AlternateDemo();

86

87        new Thread(new Runnable() {

88

89            @Override

90            public void run() {

91                for (int i = 0; i < 10; i++)

92                    ad.loopA(i);

93            }

94        }, "A").start();

95

96        new Thread(new Runnable() {

97

98            @Override

99            public void run() {

100                for (int i = 0; i < 10; i++)

101                    ad.loopB(i);

102            }

103        }, "B").start();

104

105        new Thread(new Runnable() {

106

107            @Override

108            public void run() {

109                for (int i = 0; i < 10; i++)

110                    ad.loopC(i);

111            }

112        }, "C").start();

113    }

114 }

这一期的知识点昆明IT培训的小编就给大家讲完了，之后我们还会有更多更新的资讯。