What is the difference between the wait() and sleep() methods in Java?

The wait() and sleep() methods are two methods in Java that are used for multithreading purposes. However, there are some differences between these two methods that you should be aware of when using them in your programs.

The wait() method is used to make a thread wait for a specific condition to occur. When a thread calls the wait() method, it releases the lock on the object and goes into a waiting state until another thread calls the notify() method or the notifyAll() method on the same object. Once the thread is notified, it competes with other threads for the lock on the object and proceeds with its execution.

On the other hand, the sleep() method is used to make a thread sleep for a specified amount of time. When a thread calls the sleep() method, it keeps the lock on the object and goes into a timed waiting state. After the specified time has elapsed, the thread wakes up and competes with other threads for the lock on the object and proceeds with its execution.

One important thing to note is that the wait() method can only be called from within a synchronized context. This means that the calling thread must own the lock on the object before calling the wait() method. Otherwise, a IllegalMonitorStateException will be thrown.

In summary, the wait() and sleep() methods in Java are used for different purposes. The wait() method is used for synchronization purposes, while the sleep() method is used for making a thread sleep for a specified amount of time.