线程交替打印

Posted by xdshent on July 21, 2020

线程交替打印

重点在wait和notify的协作

交替打印0、1

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
public class PrintZeroOne {

    private int count;//0、1切换

    private int num;//计数

    private final int max;//最大打印次数+1

    public PrintZeroOne(int max) {
        this.max = max;
    }

    /**
    * 打印0
    */
    public synchronized void printZero() {
        while (num < max) {
            while (count == 1) {
                try {
                    this.wait();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }

            System.out.println(Thread.currentThread().getName() + "->" + count++);
            num++;
            this.notify();
        }
    }

    /**
     * 打印1
     */
    public synchronized void printOne() {
        while (num < max) {
            while (count == 0) {
                try {
                    this.wait();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }

            System.out.println(Thread.currentThread().getName() + "->" + count--);
            num++;
            this.notify();
        }
    }

    public static void main(String[] args) {

        PrintZeroOne printZeroOne = new PrintZeroOne(5);
        new Thread(() -> {
            printZeroOne.printZero();
        }, "child").start();   //child线程

        printZeroOne.printOne(); //main线程
    }
}

结果:

1
2
3
4
5
6
child->0
main->1
child->0
main->1
child->0
main->1

交替打印奇偶数

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
public class PrintOddEven {

    private int num;

    private int max;

    public PrintOddEven(int max) {
        this.max = max;
    }

    /**
     * 打印奇数
     */
    public synchronized void odd() {
        while (num < max) {
            while ((num & 1) == 0) {
                try {
                    wait();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }

            }

            System.out.println(Thread.currentThread().getName() + " " + (num++));
            notify();
        }
    }

    /**
     * 打印偶数
     */
    public synchronized void even() {
        while (num < max) {

            while ((num & 1) == 1) {
                try {
                    wait();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }

            }

            System.out.println(Thread.currentThread().getName() + " " + (num++));
            notify();
        }
    }


    public static void main(String[] args) {
        PrintOddEven printOddEven = new PrintOddEven(100);
        new Thread(() -> {

            printOddEven.even();

        }, "偶数").start();

        new Thread(() -> {
          
            printOddEven.odd();

        }, "奇数").start();
    }
}

结果:

1
2
3
4
5
6
7
8
偶数 0
奇数 1
偶数 2
奇数 3
偶数 4
奇数 5
偶数 6
.....