Java 线程控制（输出奇偶数）

两个线程，一个输出1，3，5，7......99；另一个输出2，4，6，8......100。

1.线程同步

public class ST2 {
    int i = 0;

    public static void main(String[] args) {
        ST2 st1 = new ST2();
        new Thread(st1.new Inc()).start();
        new Thread(st1.new Dec()).start();
    }

    private synchronized void inc(){
        i++;
        try {
            Thread.currentThread().sleep(1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println(Thread.currentThread().getName()+" +++  "+i);
    }
    
    private synchronized void dec(){
        i--;
        try {
            Thread.currentThread().sleep(1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println(Thread.currentThread().getName()+" -----  "+i);
    }
    
    class Inc implements Runnable{
        @Override
        public void run() {
            while(true)
                inc();
        }
    }
    
    class Dec implements Runnable{
        @Override
        public void run() {
            while(true)
                dec();
        }
    }
}

输出：

Thread-1 -----  -1
Thread-1 -----  -2
Thread-0 +++  -1
Thread-0 +++  0
Thread-0 +++  1
Thread-0 +++  2
Thread-1 -----  1
Thread-0 +++  2
Thread-1 -----  1
Thread-1 -----  0
Thread-1 -----  -1
Thread-1 -----  -2
Thread-0 +++  -1
Thread-0 +++  0
Thread-0 +++  1
Thread-1 -----  0
Thread-1 -----  -1
Thread-1 -----  -2
Thread-1 -----  -3
Thread-1 -----  -4
Thread-0 +++  -3
Thread-0 +++  -2
Thread-0 +++  -1
Thread-0 +++  0

从这里可以看出，线程随机执行。

2.控制线程执行顺序

    private synchronized void inc() throws Exception{
        b = true;
        notifyAll();
        i++;
        System.out.println(Thread.currentThread().getName()+" ++  "+i);
        
        Thread.currentThread().sleep(1000);

        while(b)
            wait();
    }
    
    private synchronized void dec() throws Exception {
        while(!b)
            wait();
        i++;
        System.out.println(Thread.currentThread().getName()+" ++++  "+i);
        
        Thread.currentThread().sleep(1000);
         
        b = false;
        notifyAll();
    }

输出：

Thread-0 ++  1
Thread-1 ++++  2
Thread-0 ++  3
Thread-1 ++++  4
Thread-0 ++  5
Thread-1 ++++  6
Thread-0 ++  7
Thread-1 ++++  8
Thread-0 ++  9
Thread-1 ++++  10
Thread-0 ++  11
Thread-1 ++++  12
Thread-0 ++  13
Thread-1 ++++  14
Thread-0 ++  15
Thread-1 ++++  16
Thread-0 ++  17
Thread-1 ++++  18
Thread-0 ++  19
Thread-1 ++++  20
Thread-0 ++  21

3.控制线程执行次数

class Inc implements Runnable{
            @Override
            public void run() {
                    for(int j=0 ; j<50; j++){
                            try {
                                inc();
                            } catch (Exception e) {
                                e.printStackTrace();
                            }
                    }
            }
    }
    
    class Dec implements Runnable{
            @Override
            public void run() {
                for(int j=0 ; j<50; j++){
                            try {
                                dec();
                            } catch (Exception e) {
                                e.printStackTrace();
                            }
                    }
            }
    }