CODEWITHSUNDEEP
android
Sidharth
Sidharth

Reputation: 79

Method invocation may produce java NullpointerException .setText()

I am just a beginner in android development. I came by this error, when i try to set the text using ".setText()" for a text view it says it may produce null pointer exception. I am stuck and don't know what to do! Please please please Help Me Out guys!

Thanks in advance!!!

private void runTimer()
    {

     final TextView timeView = (TextView) findViewById(R.id.display_time);
     final Handler handler =new Handler();

    handler.post(new Runnable(){
        @Override

        public void run() {
                int hours = seconds/3600;
                int minutes = (seconds%3600)/60;
                int secs = seconds%60;
                String time = String.format(Locale.US,"%d:%02d:%02d",
                        hours, minutes, secs);
                timeView.setText(time);//this is where i am getting the warning!
                if (running) {
                    seconds++;
                }
            handler.postDelayed(this,1000);
        }
    });

}

Upvotes: 0

Views: 5286

Answers (3)

Tazz
Tazz

Reputation: 801

  1. Make sure you call runTimmer() after setContentView or if in fragment in onViewCreated()

  2. Make sure id: display_time is actually the real id of the TextView you want to use, check the xml file.

  3. Only the Ui Thread can make changes to the views, so you need to call runOnUiThread(new Runnable());

Upvotes: 0

Franklyn
Franklyn

Reputation: 325

Check R.id.display_time if it is pointing to the TextView in the same layout. as your activity.

Upvotes: 1

Elye
Elye

Reputation: 60081

Perhaps you could wrap a check around it as below, for the peace of mind.

private void runTimer()
{

    final TextView timeView = (TextView) findViewById(R.id.display_time);
    final Handler handler =new Handler();

    handler.post(new Runnable(){
        @Override

        public void run() {
            int hours = seconds/3600;
            int minutes = (seconds%3600)/60;
            int secs = seconds%60;
            String time = String.format(Locale.US,"%d:%02d:%02d",
                    hours, minutes, secs);
            if (timeView != null) {
                timeView.setText(time);//this is where i am getting the warning!
            }
            if (running) {
                seconds++;
            }
            handler.postDelayed(this,1000);
        }
    });

}

In the event that timeView is null for any reason (your activity ended?), no NPE will be thrown.

Upvotes: 1

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