三个线程顺序打印

主方法

  public static void main(String[] args) {
          new Thread(()-> {
              try {
                  test6("a",1,2);
              } catch (InterruptedException e) {
                  e.printStackTrace();
              }
          }).start();
          new Thread(()-> {
              try {
                  test6("b", 2, 3);
              } catch (InterruptedException e) {
                  e.printStackTrace();
              }
          }).start();
          new Thread(()-> {
              try {
                  test6("c", 3, 1);
              } catch (InterruptedException e) {
                  e.printStackTrace();
              }
          }).start();
      }

1.使用synchorined解决

static int totalFlag = 1;
static Object object = new Object();
public static void test5(String inputStr, int nowFlag, int nextFlag) {
    synchronized (object) {
        for (int i = 0; i < 3; i++) {
            while (nowFlag != totalFlag) {
                try {
                    object.wait();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
            System.out.print(inputStr);
            totalFlag = nextFlag;
            object.notifyAll();
            if(nowFlag==3){
                System.out.println();
            }
        }
    }
}

2.使用ReentrentLock解决

static ReentrantLock reentrantLock = new ReentrantLock();
static Condition aCondition = reentrantLock.newCondition();
static Condition bCondition = reentrantLock.newCondition();
static Condition cCondition = reentrantLock.newCondition();
public static void test6(String inputStr, int nowFlag, int nextFlag) throws InterruptedException {
    try {
        reentrantLock.lock();
        for (int i = 0; i < 3; i++) {
            while (nowFlag != totalFlag) {
                switch (nowFlag){
                    case 1:
                        aCondition.await();
                        break;
                    case 2:
                        bCondition.await();
                        break;
                    case 3:
                        cCondition.await();
                        break;
                }
            }
            System.out.print(inputStr);
            totalFlag = nextFlag;
            switch (nowFlag){
                case 1:
                    bCondition.signalAll();
                    break;
                case 2:
                    cCondition.signalAll();
                    break;
                case 3:
                    aCondition.signalAll();
                    break;
            }
            if(nextFlag==1){
                System.out.println();
            }
        }
    } finally {
        reentrantLock.unlock();
    }
}