Where to create Android Spinner in Fragment?

Question

My question is rather simple: how can one use(populate) Spinners in Fragments? Or better said, what is wrong with my code below? Adding Spinner as I did is as simple as it gets, but after trying in all the different ways, nothing worked. What is FragmentPagerAdapter has to do with Spinner? If I add the Spinner from a method declared somewhere else, the spinner is populated with no problems(for example if populating the spinner from a button).

Thanks in advance

public class MainActivity extends FragmentActivity {

/**
 * The {@link android.support.v4.view.PagerAdapter} that will provide
 * fragments for each of the sections. We use a
 * {@link android.support.v4.app.FragmentPagerAdapter} derivative, which
 * will keep every loaded fragment in memory. If this becomes too memory
 * intensive, it may be best to switch to a
 * {@link android.support.v4.app.FragmentStatePagerAdapter}.
 */
SectionsPagerAdapter mSectionsPagerAdapter;
public List<String> fragments = new Vector<String>();

/**
 * The {@link ViewPager} that will host the section contents.
 */
ViewPager mViewPager;
private MySQLite database;

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

    // Create the adapter that will return a fragment for each of the three
    // primary sections of the app.
    mSectionsPagerAdapter = new SectionsPagerAdapter(
            getSupportFragmentManager());

    // Set up the ViewPager with the sections adapter.
    mViewPager = (ViewPager) findViewById(R.id.pager); // pager
    mViewPager.setAdapter(mSectionsPagerAdapter);

    // We initialise the database
    database = new MySQLite(this);

    Spinner spin = (Spinner)findViewById(R.id.spinner1);
    List<String> toSpin = new ArrayList<String>();
    toSpin.add("ONE");
    toSpin.add("TWO");
    toSpin.add("THREE");
    ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,android.R.layout.simple_spinner_item,toSpin);
    spin.setAdapter(adapter);
}

@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;
}

/**
 * A {@link FragmentPagerAdapter} that returns a fragment corresponding to
 * one of the sections/tabs/pages.
 */

public class SectionsPagerAdapter extends FragmentPagerAdapter {

    public SectionsPagerAdapter(FragmentManager fm) {
        super(fm);
        fragments.add(ConnectionFragment.class.getName());
        fragments.add(DataFragment.class.getName());

    }

    @Override
    public Fragment getItem(int position) {
        // we need to instantiate the list of fragments
        return Fragment.instantiate(getBaseContext(),
                fragments.get(position));

    }

    @Override
    public int getCount() {
        // Show 3 total pages.
        return 2;
    }

    @Override
    public CharSequence getPageTitle(int position) {
        Locale l = Locale.getDefault();
        switch (position) {
        case 0:
            return getString(R.string.title_section1).toUpperCase(l);
        case 1:
            return getString(R.string.title_section2).toUpperCase(l);
        }
        return null;
    }
}

/**
 * A dummy fragment representing a section of the app, but that simply
 * displays dummy text.
 */
public static class ConnectionFragment extends Fragment {
    /**
     * The fragment argument representing the section number for this
     * fragment.
     */
    public static final String ARG_SECTION_NUMBER = "section_number";

    public ConnectionFragment() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View connectionView = inflater.inflate(
                R.layout.fragment_main_dummy, container, false);
        return connectionView;
    }
}

public static class DataFragment extends Fragment {

    public DataFragment() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View dataView = inflater.inflate(R.layout.fragment_linear,
                container, false);
        return dataView;
    }
}

Logcat:

11-16 18:26:13.092: E/AndroidRuntime(16442): FATAL EXCEPTION: main
11-16 18:26:13.092: E/AndroidRuntime(16442): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.iwallet/com.example.iwallet.MainActivity}: java.lang.NullPointerException
11-16 18:26:13.092: E/AndroidRuntime(16442):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2071)
11-16 18:26:13.092: E/AndroidRuntime(16442):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2096)
11-16 18:26:13.092: E/AndroidRuntime(16442):    at android.app.ActivityThread.access$600(ActivityThread.java:138)
11-16 18:26:13.092: E/AndroidRuntime(16442):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1207)
11-16 18:26:13.092: E/AndroidRuntime(16442):    at android.os.Handler.dispatchMessage(Handler.java:99)
11-16 18:26:13.092: E/AndroidRuntime(16442):    at android.os.Looper.loop(Looper.java:213)
11-16 18:26:13.092: E/AndroidRuntime(16442):    at android.app.ActivityThread.main(ActivityThread.java:4787)
11-16 18:26:13.092: E/AndroidRuntime(16442):    at java.lang.reflect.Method.invokeNative(Native Method)
11-16 18:26:13.092: E/AndroidRuntime(16442):    at java.lang.reflect.Method.invoke(Method.java:511)
11-16 18:26:13.092: E/AndroidRuntime(16442):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:789)
11-16 18:26:13.092: E/AndroidRuntime(16442):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:556)
11-16 18:26:13.092: E/AndroidRuntime(16442):    at dalvik.system.NativeStart.main(Native Method)
11-16 18:26:13.092: E/AndroidRuntime(16442): Caused by: java.lang.NullPointerException
11-16 18:26:13.092: E/AndroidRuntime(16442):    at com.example.iwallet.MainActivity.onCreate(MainActivity.java:65)
11-16 18:26:13.092: E/AndroidRuntime(16442):    at android.app.Activity.performCreate(Activity.java:5008)
11-16 18:26:13.092: E/AndroidRuntime(16442):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
11-16 18:26:13.092: E/AndroidRuntime(16442):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2035)
11-16 18:26:13.092: E/AndroidRuntime(16442):    ... 11 more

Answer 1

If you want to make your Spinner in your Fragment, maybe you must to declare in these Fragment in onCreatedView(). Not in onCreate() of your FragmentActivity.

And you can do it like this: Error populating spinner in a fragment