What’s the difference between sleep and wait in Java?

In Java, both sleep and wait are methods used to control the execution of threads, but they have different purposes and behaviors.

1. method to sleep

1. The sleep method belongs to the Thread class as a static method, used to pause the current thread for a certain amount of time and then resume execution.
2. Invoking the sleep method does not release the lock on the object, meaning that other threads cannot access the object.
3. The parameter of the sleep method is a time interval in milliseconds, causing the thread to pause execution for that period of time.

1. Wait method:

1. The wait method is a method belonging to the Object class, used to temporarily release a thread’s lock on an object and enter a waiting state.
2. Invoking the wait method will release the lock of the object, allowing other threads to enter and execute.
3. The wait method requires using the notify or notifyAll method to wake up the waiting threads, otherwise the threads will continue waiting indefinitely.
4. The wait method can accept a timeout value, and if no notification is received within that time frame, the thread will automatically wake up.

Summary:

1. The sleep method is a method of the Thread class, while the wait method is a method of the Object class.
2. The sleep method does not release the lock of an object, while the wait method does release the lock of an object.
3. The sleep method has a fixed duration, while the wait method allows you to set a timeout.
4. The sleep method does not need to be awakened, while the wait method needs to be awakened through the notify or notifyAll method.