Android View nullPointerException cause by setVisibility() method

Question

I'm have an issue with changing the visibility of my buttons. Whenever I use the setVisibility() method I get a nullPointerException. Here is the error I get:

04-08 15:59:02.529: E/AndroidRuntime(2807): FATAL EXCEPTION: main
04-08 15:59:02.529: E/AndroidRuntime(2807): java.lang.NullPointerException
04-08 15:59:02.529: E/AndroidRuntime(2807):     at com.android.Rides.RideTracking.onClick(RideTracking.java:307)
04-08 15:59:02.529: E/AndroidRuntime(2807):     at android.view.View.performClick(View.java:4204)
04-08 15:59:02.529: E/AndroidRuntime(2807):     at android.view.View$PerformClick.run(View.java:17355)
04-08 15:59:02.529: E/AndroidRuntime(2807):     at android.os.Handler.handleCallback(Handler.java:725)
04-08 15:59:02.529: E/AndroidRuntime(2807):     at android.os.Handler.dispatchMessage(Handler.java:92)
04-08 15:59:02.529: E/AndroidRuntime(2807):     at android.os.Looper.loop(Looper.java:137)
04-08 15:59:02.529: E/AndroidRuntime(2807):     at android.app.ActivityThread.main(ActivityThread.java:5041)
04-08 15:59:02.529: E/AndroidRuntime(2807):     at java.lang.reflect.Method.invokeNative(Native Method)
04-08 15:59:02.529: E/AndroidRuntime(2807):     at java.lang.reflect.Method.invoke(Method.java:511)
04-08 15:59:02.529: E/AndroidRuntime(2807):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
04-08 15:59:02.529: E/AndroidRuntime(2807):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
04-08 15:59:02.529: E/AndroidRuntime(2807):     at dalvik.system.NativeStart.main(Native Method)

Here is the code:

        public View btnStart = null;
        public View btnPause = null;
        public View btnResume = null;

        case R.id.btnPauseRide:
            mLoggerServiceManager.pauseGPSLogging();

            setResult( RESULT_OK, intent );
            btnPause.setVisibility(View.GONE);
            btnResume.setVisibility(View.VISIBLE);
            break;

        case R.id.btnResumeRide: 
            mLoggerServiceManager.resumeGPSLogging();
            setResult(RESULT_OK, intent);

            btnResume.setVisibility(View.GONE);
            btnPause.setVisibility(View.VISIBLE);
        default:
                            break;

Any help would be greatly appreciated.

codeMagic · Accepted Answer · 2013-04-08T16:27:17.897

This is because

 public View btnPause = null;

you set the button to null. You need to assign it. Assuming you have already called setContentView() and the button is in that layout

btnPause = (Button) findViewwById(R.id.button_id);

You have all of your buttons set to null then trying to call a method on them, setVisibility(), which will return null every time

If you are wanting to hide the Button that is pressed then you can just do

    case R.id.btnPauseRide:
        mLoggerServiceManager.pauseGPSLogging();

        setResult( RESULT_OK, intent );
        btnPPauseRide.setVisibility(View.GONE);
        btnResume.setVisibility(View.VISIBLE);
        break;

instead of creating these new Views unless you have something else going on

score 1 · Answer 2 · answered Apr 08 '13 at 16:13

1

Looks like the variable you are trying to access is not set. Check your onCreate method if you set it and actually find it.

answered Apr 08 '13 at 16:13

meredrica

2,527
1
19
24

score 1 · Answer 3 · answered Apr 08 '13 at 16:14

1

You are getting the null pointer exception because you are assigning the view as null. Instead, try initializing the View via either:

public View btnPause = findViewById(R.id.btnPause);

or....

public View btnPause = new View(this);

answered Apr 08 '13 at 16:14

sngreco

1,098
11
16

Android View nullPointerException cause by setVisibility() method

3 Answers3