Can the wait() method be used on an object without holding a synchronized lock?

No, the wait() method on an object in Java can only be called if the current thread owns the monitor of that object, meaning it is inside a synchronized block synchronized on that object. Calling wait() without holding the lock will throw an IllegalMonitorStateException.

Example of correct usage:

synchronized(obj) {
    obj.wait();
}

This is because wait() releases the monitor and puts the thread into a waiting state, and for proper operation, the monitor must be acquired.