多线程死锁问题

同步中嵌套同步,导致锁无法释放

package com.toov5.threadSecurity;
class Thread009 implements Runnable {
    private int trainCount = 100;
    private Object oj = new Object();
    public boolean flag = true;

    public void run() {

        if (flag) {
            while (trainCount > 0) {
                synchronized (oj) {
                    try {
                        Thread.sleep(10);
                    } catch (Exception e) {
                        // TODO: handle exception
                    }
                    sale();
                }

            }
        } else {
            while (trainCount > 0) {
                sale();
            }

        }

    }

    public synchronized void sale() {
        synchronized (oj) {
            try {
                Thread.sleep(10);
            } catch (Exception e) {

            }
            if (trainCount > 0) {
                System.out.println(Thread.currentThread().getName() + "," + "出售第" + (100 - trainCount + 1) + "票");
                trainCount--;
            }
        }
    }
}

public class Test009 {
    public static void main(String[] args) throws InterruptedException {
        Thread009 threadTrain = new Thread009();
        Thread t1 = new Thread(threadTrain, "窗口1");
        Thread t2 = new Thread(threadTrain, "窗口2");
        t1.start();
        Thread.sleep(40);
        threadTrain.flag = false;
        t2.start();

    }
}

t1先获取oj锁，然后this锁，才能把程序执行完毕

t2现货区this锁，再获取oj锁，才能把程序执行完毕

结果：