Object not locked by thread before notify() in onPostExecute

 

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I try to notify adapters of listviews of main class in onPostExecute but I receive the error: java.lang.IllegalMonitorStateException:object not locked by thread before notify()

@Override
protected void onPostExecute(String result) {
    popularfragment.adapter.notifyDataSetChanged();
    recentfragment.adapter.notifyDataSetChanged();
}

java  android  multithreading

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asked  Jun 12 '14 at 13:38

Erkan Erol

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2 Answers

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The .notify() method has to be called from within a synchronized context, ie from inside a synchronized block.

The java.lang.IllegalMonitorStateException is thrown when you call .notify() on an object that is not used as the lock for the synchronized block in which you call notify. For example, the following works;

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

But this will throw the exception;

synchronized(obj){
    // notify() is being called here when the thread and 
    // synchronized block does not own the lock on the object.
    anotherObj.notify();        
}

Reference;

• IllegalMonitorStateException API
• How to use wait & notify

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edited May 23 '17 at 11:55

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answered  Jun 12 '14 at 13:48

Rudi Kershaw

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I had the same error, but (for me) the answer suggested by Rudi Kershaw wasn't the issue... I called the notify() of a Notification the wrong way (see the last line of both snippets):

Not working:

public void update() {
    mBuilder.setSmallIcon(R.drawable.ic_launcher)
            .setPriority(AesPrefs.getInt(R.string.PRIORITY_NOTIFICATION_BATTERY, NotificationCompat.PRIORITY_MAX))
            .setOngoing(true);
    mBuilder.setWhen(AesPrefs.getLong(Loader.gStr(R.string.LAST_FIRED_BATTERY_NOTIFICATION) + Const.START_CLIPBOARD_NOTIFICATION_DELAYED, -1));
    mManager.notify(); // <- lil' mistake
}

Working:

public void update() {
    mBuilder.setSmallIcon(R.drawable.ic_launcher)
            .setPriority(AesPrefs.getInt(R.string.PRIORITY_NOTIFICATION_BATTERY, NotificationCompat.PRIORITY_MAX))
            .setOngoing(true);
    mBuilder.setWhen(AesPrefs.getLong(Loader.gStr(R.string.LAST_FIRED_BATTERY_NOTIFICATION) + Const.START_CLIPBOARD_NOTIFICATION_DELAYED, -1));
    mManager.notify(Const.NOTIFICATION_CLIPBOARD, mBuilder.build()); // <- ok ;-)
}

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answered  Dec 29 '15 at 20:19

Martin Pfeffer

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https://stackoverflow.com/questions/24185921/object-not-locked-by-thread-before-notify-in-onpostexecute