1package com.oho.alg;
  2
  3import java.util.concurrent.locks.Condition;
  4import java.util.concurrent.locks.Lock;
  5import java.util.concurrent.locks.ReentrantLock;
  6
  7public class PrintNums {
  8
  9  public final Lock lock = new ReentrantLock();
 10  public Condition c0 = lock.newCondition();
 11  public Condition c1 = lock.newCondition();
 12  public int flag = 0;
 13
 14  private void print0(int num) {
 15
 16    lock.lock();
 17    try {
 18
 19      for (int i = 1; i <= num; i++) {
 20        if (flag == 0) {
 21          System.out.print(0);
 22          flag = 1;
 23          c1.signal();
 24          c0.await();
 25        }
 26
 27      }
 28
 29    } catch (InterruptedException e) {
 30      e.printStackTrace();
 31    } finally {
 32      lock.unlock();
 33    }
 34
 35  }
 36
 37  private void print(int num) {
 38
 39    lock.lock();
 40    try {
 41
 42      for (int i = 1; i <= num; i++) {
 43        if (flag == 1) {
 44
 45          System.out.print(i);
 46          flag = 0;
 47          c0.signal();
 48
 49          if (i < num) {
 50            c1.await();
 51          }
 52
 53        }
 54
 55      }
 56
 57    } catch (InterruptedException e) {
 58      e.printStackTrace();
 59    } finally {
 60      lock.unlock();
 61    }
 62
 63  }
 64
 65  public void printNumsWithNum(int num) {
 66
 67    long start = System.currentTimeMillis();
 68
 69    Thread t1 = new Thread(() -> print0(num));
 70    Thread t2 = new Thread(() -> print(num));
 71
 72    t1.start();
 73    t2.start();
 74
 75    try {
 76      t1.join();
 77      t2.join();
 78    } catch (InterruptedException e) {
 79      e.printStackTrace();
 80    }
 81    System.out.println();
 82    System.out.println("===============================================");
 83    System.out.println("运行时长: " + (System.currentTimeMillis() - start));
 84
 85  }
 86
 87  public static void main(String[] args) {
 88
 89    new PrintNums().printNumsWithNum(10);
 90
 91  }
 92}
 93
 94```java
 95
 96第二种解法：Semaphore
 97
 98```cs
 99package com.oho.alg;
100
101import java.util.concurrent.Semaphore;
102
103public class PrintNumsUseSemaphore {
104
105  public Semaphore s1 = new Semaphore(1);
106  public Semaphore s2 = new Semaphore(0);
107
108  private void print0(int num) {
109
110    try {
111
112      for (int i = 1; i <= num; i++) {
113        //获取信号量，s1 - 1
114        s1.acquire();
115        System.out.print(0);
116        //释放信号量，s2 + 1
117        s2.release();
118      }
119
120    } catch (InterruptedException e) {
121      e.printStackTrace();
122    }
123
124  }
125
126  private void print(int num) {
127
128    try {
129      for (int i = 1; i <= num; i++) {
130        //获取信号量，s2 - 1
131        s2.acquire();
132        System.out.print(i);
133        //释放信号量，s1 + 1
134        s1.release();
135      }
136
137    } catch (InterruptedException e) {
138      e.printStackTrace();
139    }
140
141  }
142
143  public void printNumsWithNum(int num) {
144
145    long start = System.currentTimeMillis();
146
147    Thread t1 = new Thread(() -> print0(num));
148    Thread t2 = new Thread(() -> print(num));
149
150    t1.start();
151    t2.start();
152
153    try {
154      t1.join();
155      t2.join();
156    } catch (InterruptedException e) {
157      e.printStackTrace();
158    }
159    System.out.println();
160    System.out.println("===============================================");
161    System.out.println("运行时长: " + (System.currentTimeMillis() - start));
162
163  }
164
165  public static void main(String[] args) {
166
167    new PrintNumsUseSemaphore().printNumsWithNum(10);
168
169  }
170}