Android 'notify()' Error: Object Not Locked by Thread

This error message typically occurs when you call the 'notify()' method on an object without first acquiring its lock using the 'synchronized' keyword. In Java, the 'wait()' and 'notify()' methods can only be called on an object while holding its lock.

To fix this error, you should ensure that you are using the 'synchronized' keyword to acquire the lock on the object before calling 'notify()'. Here's an example:

// Acquiring the lock
synchronized (object) {
    // Performing some operations

    // Notifying other threads waiting on the object's lock
    object.notify();
}

Make sure that you are synchronizing on the correct object and that you have acquired its lock before calling 'notify()'.