What does the wait method do in Java?

The current thread is put into a waiting state (releasing the object's lock) until another thread calls the notify() or notifyAll() method on the same object, or until a timeout occurs. It is used in synchronized blocks or methods.

// Example of using wait() and notify()
public class SharedObject {
    private boolean dataAvailable = false;

    public synchronized void waitForData() throws InterruptedException {
        while (!dataAvailable) {
            // Thread waits until data becomes available
            wait(); 
        }
        // Data processing
        System.out.println("Data received.");
    }

    public synchronized void sendData() {
        // Sending data
        dataAvailable = true;
        // Notify waiting threads
        notifyAll(); 
        System.out.println("Data sent.");
    }
}

Key points:

• Called only from a synchronized context (block or method).
• The thread releases the lock on the object for which wait() was called.
• Can be interrupted (InterruptedException).
• Has overloaded versions with timeout.
• notify() wakes up one of the waiting threads.
• notifyAll() wakes up all waiting threads.