CODEWITHSUNDEEP
androidandroid-fragmentsandroid-spinner
Dumbo
Dumbo

Reputation: 14112

NullPointerException with Android API18 and fragment layout

I've created a new project with Android Studio v3.2, used API 18 and it created the default app just fine.

I added a spinner to the fragment file (First time I am using it, I am not sure if this is the problem).

No I simply wanted to add some dummy items to the spinner on the fly but my app keeps crashing with Unofrotunately....has stopped message.

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_app_start);

        if (savedInstanceState == null) {
            getFragmentManager().beginTransaction()
                    .add(R.id.container, new PlaceholderFragment())
                    .commit();
        }
    //Just added this!
    String[] movies = new String[]{"one, two, three"};
    ArrayAdapter<String> movieAdapter = new ArrayAdapter<String>(this, R.id.app_start_select_movie_spinner, movies );
    Spinner spinner = (Spinner)findViewById(R.id.app_start_select_movie_spinner);
    spinner.setAdapter(movieAdapter);
}

Here is the message in logcat:

11-06 23:57:29.174  16743-16743/org.pervasivesystems.nexusmosaic E/AndroidRuntime﹕ FATAL EXCEPTION: main
    java.lang.RuntimeException: Unable to start activity ComponentInfo{org.pervasivesystems.nexusmosaic/org.pervasivesystems.nexusmosaic.activity_app_start}: java.lang.NullPointerException
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2211)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261)
            at android.app.ActivityThread.access$600(ActivityThread.java:141)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:137)
            at android.app.ActivityThread.main(ActivityThread.java:5103)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:525)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: java.lang.NullPointerException
            at org.pervasivesystems.nexusmosaic.activity_app_start.onCreate(activity_app_start.java:32)
            at android.app.Activity.performCreate(Activity.java:5133)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2175)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261)
            at android.app.ActivityThread.access$600(ActivityThread.java:141)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:137)
            at android.app.ActivityThread.main(ActivityThread.java:5103)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:525)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
            at dalvik.system.NativeStart.main(Native Method)

line 32 is:

spinner.setAdapter(movieAdapter);

So basically the spinner is null...somehow it couldnt be assigned

It might be very simple but I couldnt figure it out :(

Upvotes: 0

Views: 634

Answers (1)

frogmanx
frogmanx

Reputation: 2630

You are using the same resource for both the spinner and the adapter spinner item (which expects a pointer to a layout resource file, not a view object).

ArrayAdapter<String> movieAdapter = new ArrayAdapter<String>(this, R.id.app_start_select_movie_spinner, movies );
Spinner spinner = (Spinner)findViewById(R.id.app_start_select_movie_spinner);

Instead, try: 

ArrayAdapter<String> movieAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item, movies );
Spinner spinner = (Spinner)findViewById(R.id.app_start_select_movie_spinner);

Also, try moving adapter initialisation into your fragment's onCreateView.

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {

        View rootView = inflater.inflate(R.layout.your_fragment, container, false);

        String[] movies = new String[]{"one, two, three"};
        ArrayAdapter<String> movieAdapter = new ArrayAdapter<String>(getActivity(), android.R.layout.simple_spinner_item, movies );
        Spinner spinner = (Spinner)rootView.findViewById(R.id.app_start_select_movie_spinner);
        spinner.setAdapter(movieAdapter);
        return rootView;
}

For accessing the fragment from the activity, have a look at the fragment google dev docs.

In essence, you can get the fragment's root view from your activity by using the following code, but it can be a bit hit and miss:

YourFragment yourFragment = (YourFragment) getFragmentManager().findViewById(R.id.your_fragment);
if(yourFragment != null)
{
    View fragmentRootView = (View) yourFragment.getView();
    //do your manipulation here.
}

Upvotes: 2

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