多线程案例_循环打印_设计4个线程...

要求：设计4个线程，其中两个线程每次对 i 增加1，另外两个线程对 i 每次减少1，写出程序。
在以下程序中，numOfPrint 代表题目中的 i
为了解决本方唤醒其他一方的问题。可以一个锁创建多个监视器对象(Condition对象)。
  1 import java.util.concurrent.locks.Condition;
  2 import java.util.concurrent.locks.Lock;
  3 import java.util.concurrent.locks.ReentrantLock;
  4 
  5 /**
  6  * @author 馬建超 2018年1月19日 上午11:45:39
  7  */
  8 public class ThreadTest6 {
  9     public static void main(String[] args) {
 10         final NumberIncreate ni = new NumberIncreate();
 11         new Thread(new Runnable() {
 12 
 13             @Override
 14             public void run() {
 15                 for (int i = 0; i < 5; i++) {
 16                     ni.num();
 17                 }
 18 
 19             }
 20         }, "A").start();
 21         new Thread(new Runnable() {
 22 
 23             @Override
 24             public void run() {
 25                 for (int i = 0; i < 5; i++) {
 26                     ni.num2();
 27                 }
 28 
 29             }
 30         }, "B").start();
 31         new Thread(new Runnable() {
 32 
 33             @Override
 34             public void run() {
 35                 for (int i = 0; i < 5; i++) {
 36                     ni.num3();
 37                 }
 38 
 39             }
 40         }, "C").start();
 41         new Thread(new Runnable() {
 42 
 43             @Override
 44             public void run() {
 45                 for (int i = 0; i < 5; i++) {
 46                     ni.num4();
 47                 }
 48 
 49             }
 50         }, "D").start();
 51     }
 52 
 53 }
 54 
 55 class NumberIncreate {
 56     private int num = 1;// 当前正在执行线程的标记
 57     private int numOfPrint = 0;// 打印的数字
 58     private Lock lock = new ReentrantLock();
 59     Condition condition = lock.newCondition();
 60     Condition condition2 = lock.newCondition();
 61     Condition condition3 = lock.newCondition();
 62     Condition condition4 = lock.newCondition();
 63 
 64     public void num() {
 65         lock.lock();
 66         try {
 67             if (num != 1) {
 68                 condition.await();
 69             }
 70             System.out.println("numOfPrint==" + numOfPrint++);
 71             num = 2;
 72             condition2.signal();
 73         } catch (Exception e) {
 74         } finally {
 75             lock.unlock();
 76         }
 77 
 78     }
 79 
 80     public void num2() {
 81         lock.lock();
 82         try {
 83             if (num != 2) {
 84                 condition2.await();
 85             }
 86             System.out.println("numOfPrint==" + numOfPrint++);
 87             num = 3;
 88             condition3.signal();
 89         } catch (Exception e) {
 90         } finally {
 91             lock.unlock();
 92         }
 93 
 94     }
 95 
 96     public void num3() {
 97         lock.lock();
 98         try {
 99             if (num != 3) {
100                 condition3.await();
101             }
102             System.out.println("numOfPrint==" + numOfPrint--);
103             num = 4;
104             condition4.signal();
105         } catch (Exception e) {
106         } finally {
107             lock.unlock();
108         }
109 
110     }
111 
112     public void num4() {
113         lock.lock();
114         try {
115             if (num != 4) {
116                 condition4.await();
117             }
118             System.out.println("numOfPrint==" + numOfPrint--);
119             num = 1;
120             condition.signal();
121         } catch (Exception e) {
122         } finally {
123             lock.unlock();
124         }
125 
126     }
127 }
纸上学来终觉浅，觉知此事需躬行