成都Java后端开发常考面试题有哪些？

class ShareDataLock{
    // 线程执行的条件 1：线程1执行 2：线程2执行 3：线程3执行
    int number =1;
    // 锁
    Lock lock = new ReentrantLock();
    // 从锁中获得3个条件变量
    Condition condition1 = lock.newCondition();
    Condition condition2 = lock.newCondition();
    Condition condition3 = lock.newCondition();

    // 第一个线程run之后执行的方法
    public void f1(){
        lock.lock();
        try {
            // 如果条件值不为1 就挂起等待
            while(number!=1){
                condition1.await();
            }
            // 故意阻塞100毫秒，看看其他的线程会不会不再排队
            Thread.sleep(100);
            System.out.println("------1--------");
            // 线程1 执行完毕 把变量设置为2
            number = 2;
            // 唤醒第2个条件变量
            condition2.signal();
        } catch (Exception e) {
          e.printStackTrace();
        } finally {
            // 不管抛没抛出异常都要解锁，防止线程死锁
          lock.unlock();
        }
    }
    
    public void f2(){
        lock.lock();
        try {
            while(number!=2){
                condition2.await();
            }
            System.out.println("------2--------");
            number = 3;
            condition3.signal();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            lock.unlock();
        }
    }
    
    public void f3(){
        lock.lock();
        try {
            while(number!=3){
                condition3.await();
            }
            System.out.println("------3--------");
            number = 1;
            condition1.signal();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            lock.unlock();
        }
    }
}

public class SynchronizedAndReentrantLockDemo {

    public static void main(String[] args) {
        ShareDataLock shareDataLock = new ShareDataLock();
        for (int i = 0; i < 10; i++) {
            // 3个线程分别执行1,2,3 3个方法 ，并且同时就绪
            new Thread(()->shareDataLock.f1(),"AA").start();
            new Thread(()->shareDataLock.f2(),"bb").start();
            new Thread(()->shareDataLock.f3(),"cc").start();
        }

    }
}