试题一

试题一

题目:

• /**
   * Created by fan on 2019/11/4.
   * <p>
   * 三个线程A,B,C
   * A打印AA  5次
   * B打印BB 10 次
   * C打印CC 15 次
   * <p>
   * A->B->C依次打印
   * 轮询 10 次
   */
  

实现

• public class LockChangeSynchonized {
      public static void main(String[] args) throws Exception {
          Resource resource = new Resource();
          Lock lock = new ReentrantLock();
  
          Condition conditionA = lock.newCondition();
          Condition conditionB = lock.newCondition();
          Condition conditionC = lock.newCondition();
  
          new Thread(() -> {
              lock.lock();
              try {
                  for (int i = 0; i < 10; i++) {
  
                      while (resource.getFlag() != 1) {
                          conditionA.await();
                      }
  
                      resource.print(5, "AA");
  
                      resource.setFlag(2);
  
                      conditionB.signal();
                  }
              } catch (Exception e) {
                  e.printStackTrace();
              } finally {
                  lock.unlock();
              }
          }, "A").start();
  
          new Thread(() -> {
              lock.lock();
              try {
  
                  for (int i = 0; i < 10; i++) {
  
                      while (resource.getFlag() != 2) {
                          conditionB.await();
                      }
                      resource.print(10, "BB");
  
                      resource.setFlag(3);
  
                      conditionC.signal();
                  }
  
              } catch (Exception e) {
                  e.printStackTrace();
              } finally {
                  lock.unlock();
              }
          }, "B").start();
  
          new Thread(() -> {
              lock.lock();
              try {
  
                  for (int i = 0; i < 10; i++) {
  
                      while (resource.getFlag() != 3) {
                          conditionC.await();
                      }
                      resource.print(15, "CC");
  
                      resource.setFlag(1);
  
                      conditionA.signal();
                  }
  
              } catch (Exception e) {
                  e.printStackTrace();
              } finally {
                  lock.unlock();
              }
          }, "C").start();
      }
  }
  
  
  class Resource {
      private int flag = 1;
  
      public int getFlag() {
          return flag;
      }
  
      public void setFlag(int flag) {
          this.flag = flag;
      }
  
      public void print(int count, String content) {
          for (int i = 0; i < count; i++) {
              System.out.println(Thread.currentThread().getName() + "\t" + content + "\t" + (i + 1));
          }
      }
  }