code after synchronized block in java is unreachable but semp.release() is not

Question

Thread faculty = new Thread(() -> {
                try {
                    while (true) {


         boolean is_grab = false;
                    semp.acquire();
                    if (candy > 0) {
                        System.out.println("No." + NO + " faculty grabs a candy");
                        candy--;
                        is_grab = true;
                        System.out.println("Candy num left:" + candy);
                    }
                    semp.release();
                    if (is_grab) {
                        Thread.sleep(1000);
                    }
                }
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        });
        faculty.start();
    }

In the code above, I use a semaphore implementation for synchronization and if (is_grab) { Thread.sleep(1000); } could be executed.

However, in code below,

Thread faculty = new Thread(() -> {
                synchronized (Bowl.class) {
                    while (true) {
                        while (Bowl.candy <= 0) {
                            try {
                                Bowl.class.wait();
                            } catch (InterruptedException e) {
                                e.printStackTrace();
                            }
                        }
                        System.out.println("No." + NO + " faculty grabs a candy");
                        Bowl.candy--;
                        System.out.println("Candy num left:" + Bowl.candy);
                        Bowl.class.notifyAll();
                    }
                }
                try {
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            });

I use synchronized on Bowl.class but try{sleep} is unreachable. Why?

Answer 1

在下面的示例中，没有break语句可以退出while(true)循环。