Compare the sleep() and wait() methods in Java

In Java, both sleep() and wait() methods are used to pause the execution of a thread, but they serve different purposes and are used in different contexts.

sleep() Method:

• Class Belonging: sleep() is a static method of the Thread class.
• Purpose: It is used to pause the execution of the current thread for a specified duration of time.
• Lock Behavior: When a thread is put to sleep, it holds any locks it has – it does not release any object locks.
• Usage Context: sleep() can be called from any context and is not dependent on the object's monitor.
• Method Signature: sleep() has two overloaded versions: sleep(long millis) and sleep(long millis, int nanos), both of which can throw InterruptedException.
• Interruption: If another thread interrupts the sleeping thread, it throws an InterruptedException.
• Static Method: Being a static method, sleep() always affects the current executing thread, regardless of which thread object calls it.

wait() Method:

• Class Belonging: wait() is a non-static method and is part of the Object class.
• Purpose: It causes the current thread to wait until another thread invokes notify() or notifyAll() on the same object or until the optional timeout expires.
• Lock Behavior: When wait() is invoked, the calling thread releases the lock on the object to allow other threads to synchronize on that object.
• Usage Context: wait() must be called from a synchronized context – the calling thread must own the object's monitor.
• Method Signature: wait() has three versions: wait(), wait(long timeout), and wait(long timeout, int nanos), all of which can throw InterruptedException.
• Interruption: A thread in wait() state can be woken up before the notify call or timeout by an InterruptedException.
• Object Lock: wait() is always about the object lock; when a thread calls wait(), it sets itself in a wait state on that object's monitor.

Key Differences:

• Lock Release: wait() releases the monitor lock, sleep() does not.
• Class Membership: wait() is in Object class, sleep() is ...