App has stopped working on using display.setText()

Question

I am little new to Android Programming but I am very familiar with Java and C++. Following is my Java code of my app it works on toast but when I tried to change text it causes "Your App has stopped working".

Code

public class MainActivity extends ActionBarActivity {

int counter;
Button sum, sub;
TextView display;

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    counter = 0;
    display = (TextView) findViewById(R.id.show);
    if (savedInstanceState == null) {
        getSupportFragmentManager().beginTransaction()
                .add(R.id.container, new PlaceholderFragment()).commit();
    }
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {

    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);
}

/**
 * A placeholder fragment containing a simple view.
 */
public static class PlaceholderFragment extends Fragment {

    public PlaceholderFragment() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_main, container,
                false);
        return rootView;
    }
}
public void addButtonClicked(View v) {
     counter++;
     tToast("Your Total Is : " + counter);
        display.setText("Your Total Is : " + counter);

    }
public void subButtonClicked(View v) {
     counter--;
     tToast("Your Total Is : " + counter);
        display.setText("Your Total Is : " + counter);

    }
 private void tToast(String s) {
        Context context = getApplicationContext();
        int duration = Toast.LENGTH_LONG;
        Toast toast = Toast.makeText(context, s, duration);
        toast.show();
    }
}

StackTrace :

07-05 05:22:42.888: E/AndroidRuntime(1650): FATAL EXCEPTION: main
07-05 05:22:42.888: E/AndroidRuntime(1650): Process: com.example.counter, PID: 1650
07-05 05:22:42.888: E/AndroidRuntime(1650): java.lang.IllegalStateException: Could not execute method of the activity
07-05 05:22:42.888: E/AndroidRuntime(1650):     at android.view.View$1.onClick(View.java:3823)
07-05 05:22:42.888: E/AndroidRuntime(1650):     at android.view.View.performClick(View.java:4438)
07-05 05:22:42.888: E/AndroidRuntime(1650):     at android.view.View$PerformClick.run(View.java:18422)
07-05 05:22:42.888: E/AndroidRuntime(1650):     at android.os.Handler.handleCallback(Handler.java:733)
07-05 05:22:42.888: E/AndroidRuntime(1650):     at android.os.Handler.dispatchMessage(Handler.java:95)
07-05 05:22:42.888: E/AndroidRuntime(1650):     at android.os.Looper.loop(Looper.java:136)
07-05 05:22:42.888: E/AndroidRuntime(1650):     at android.app.ActivityThread.main(ActivityThread.java:5017)
07-05 05:22:42.888: E/AndroidRuntime(1650):     at java.lang.reflect.Method.invokeNative(Native Method)
07-05 05:22:42.888: E/AndroidRuntime(1650):     at java.lang.reflect.Method.invoke(Method.java:515)
07-05 05:22:42.888: E/AndroidRuntime(1650):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
07-05 05:22:42.888: E/AndroidRuntime(1650):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
07-05 05:22:42.888: E/AndroidRuntime(1650):     at dalvik.system.NativeStart.main(Native Method)
07-05 05:22:42.888: E/AndroidRuntime(1650): Caused by: java.lang.reflect.InvocationTargetException
07-05 05:22:42.888: E/AndroidRuntime(1650):     at java.lang.reflect.Method.invokeNative(Native Method)
07-05 05:22:42.888: E/AndroidRuntime(1650):     at java.lang.reflect.Method.invoke(Method.java:515)
07-05 05:22:42.888: E/AndroidRuntime(1650):     at android.view.View$1.onClick(View.java:3818)
07-05 05:22:42.888: E/AndroidRuntime(1650):     ... 11 more
07-05 05:22:42.888: E/AndroidRuntime(1650): Caused by: java.lang.NullPointerException
07-05 05:22:42.888: E/AndroidRuntime(1650):     at com.example.counter.MainActivity.addButtonClicked(MainActivity.java:104)
07-05 05:22:42.888: E/AndroidRuntime(1650):     ... 14 more

Likely the view belongs to the Fragment. So initialize display in Fragment's onCreateView and set text there. You initialize button and set click listener for the same in Fragment — Raghunandan, Jul 05 '14 at 09:12
where have you put your textview?? in fragment_main or activity_main.xml??? — Lal, Jul 05 '14 at 09:13
Please post the log from your logcat in order to analyze the issue — hungr, Jul 05 '14 at 09:14
If I had a penny for every time someone makes this error with placeholder fragment... — Yaroslav Mytkalyk, Jul 05 '14 at 09:15
How can I post my whole Logcat its like of 1000 lines hungr Second thing I have told you in my post that I am new to Android so what is fragment_main?? — Wasif Khan, Jul 05 '14 at 09:16
@user3125340 need not post 1000 lines. You can post the exception part oonly — Raghunandan, Jul 05 '14 at 09:17
@user3125340 need not comment. edit and post the same in your post — Raghunandan, Jul 05 '14 at 09:20
Hey you marked my question as duplicate and did not answer my question :/ — Wasif Khan, Jul 05 '14 at 09:30
@user3125340 Look at the link at the top of your post carefully. If you read that you should be able to fix it yourself. Its a duplicate hence voted to close — Raghunandan, Jul 05 '14 at 09:31
Raghunandan I want to message you personally how can I contact you? — Wasif Khan, Jul 05 '14 at 09:35

Lal · Accepted Answer · 2014-07-05T11:27:15.823

1

This is because findViewById() searches in the activity_main layout, while the TextView is located in the fragment's layout fragment_main.

Move that piece of code in the onCreateView() method of the fragment:

//...
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
display = (TextView)rootView.findViewById(R.id.show);

Notice that now you access it through rootView view:

display = (TextView)rootView.findViewById(R.id.show);

otherwise you would get again NullPointerException.

edited Jul 05 '14 at 11:27

answered Jul 05 '14 at 09:15

Lal

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When I moved it.. It caused error Cannot make a static reference to the non-static method findViewById(int) from the type Activity – Wasif Khan Jul 05 '14 at 09:53
I've dited my answer..Try it once more.. @user3125340 – Lal Jul 05 '14 at 10:06
@Lal this is still wrong. You have the initialization before inflating the layout. Also the button should be initialized in onCreateview and op should remove` android:onClick="addButtonClicked"` and have a click listener in fragment – Raghunandan Jul 05 '14 at 11:16
Sorry..That was a mistake...I've edited my answer.. – Lal Jul 05 '14 at 11:18
@Lal still wrong `display` cannot be accessed in activity. Notice `display.setText("Your Total Is : " + counter);` in activity – Raghunandan Jul 05 '14 at 11:19
Is it ok now...?? @Raghunandan – Lal Jul 05 '14 at 11:29

App has stopped working on using display.setText()

1 Answers1