What is wrong with this code to use a ViewPager?

Question

I'm trying to get a very basic program working that uses a ViewPager. But I get java error when I try to execute it on my phone. Here is the code (I'm trying to do a modified version of the tutorial)

public class MainActivity extends ActionBarActivity {

private ViewPager pager;
private PagerAdapter pageAdapter;

private class ScreenSlidePagerAdapter extends FragmentStatePagerAdapter {
    public ScreenSlidePagerAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override
    public Fragment getItem(int position) {
        CardListFragment clf = new CardListFragment();
        if (position == 0) clf.setThetext("Hola");
        else if (position == 1) clf.setThetext("Mundo");
        else if (position == 2) clf.setThetext("Cruel");
        return clf;
    }

    @Override
    public int getCount() {
        return 3;
    }
}

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

    LinearLayout ll = new LinearLayout(this);
    ll.setOrientation(LinearLayout.VERTICAL);
    ll.setLayoutParams(new LinearLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT));


    pager = new ViewPager(this);
    pager.setLayoutParams(new LinearLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT));
    pageAdapter = new ScreenSlidePagerAdapter(getSupportFragmentManager());
    pager.setAdapter(pageAdapter);

    ll.addView(pager);
    setContentView(ll);
}
}

And the CardListFragment

public class CardListFragment extends Fragment {

public void setThetext(String thetext) {
    this.thetext = thetext;
}

private String thetext = "Antes";

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

    TextView textView = new TextView(container.getContext());
    textView.setTextSize(28);
    textView.setText(thetext);

    return textView;
}
}

The error I get is (stack trace):

21385-21385/lengendary.app E/AndroidRuntime﹕ FATAL EXCEPTION: main
android.content.res.Resources$NotFoundException: Unable to find resource ID #0xffffffff
        at android.content.res.Resources.getResourceName(Resources.java:1686)
        at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:919)
        at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1104)
        at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:682)
        at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1467)
        at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:472)
        at android.support.v4.app.FragmentStatePagerAdapter.finishUpdate(FragmentStatePagerAdapter.java:163)
        at android.support.v4.view.ViewPager.populate(ViewPager.java:1068)
        at android.support.v4.view.ViewPager.populate(ViewPager.java:914)
        at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1436)
        at android.view.View.measure(View.java:15593)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825)
        at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404)
        at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
        at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
        at android.view.View.measure(View.java:15593)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:314)
        at android.view.View.measure(View.java:15593)
        at android.widget.LinearLayout.measureVertical(LinearLayout.java:847)
        at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
        at android.view.View.measure(View.java:15593)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:314)
        at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2183)
        at android.view.View.measure(View.java:15593)
        at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1878)
        at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1089)
        at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1265)
        at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:989)
        at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4356)
        at android.view.Choreographer$CallbackRecord.run(Choreographer.java:749)
        at android.view.Choreographer.doCallbacks(Choreographer.java:562)
        at android.view.Choreographer.doFrame(Choreographer.java:532)
        at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:735)
        at android.os.Handler.handleCallback(Handler.java:725)
        at android.os.Handler.dispatchMessage(Handler.java:92)
        at android.os.Looper.loop(Looper.java:213)
        at android.app.ActivityThread.main(ActivityThread.java:5092)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:511)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:797)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:564)
        at dalvik.system.NativeStart.main(Native Method)

Any ideas on what I'm doing wrong?

I didn't want to use one. I rather just do it programatically. But apparetly there is no choice... — aarelovich, Mar 22 '14 at 16:59
I think your have same problem. See this http://stackoverflow.com/questions/15262261/android-content-res-resourcesnotfoundexception-unable-to-find-resource-id-0xf — vmtrue, Mar 22 '14 at 18:35
You are right. Seem like the same problem. I had guessed it had something to do with the ID for one simple reason. The default code generated by Android Studio for a ViewPager (which worked) was that the xml set that ID and I didn't programatically. But since I didn't know how to set it, I went with using the xml for simplicity. However I will check this out if I get problems in the future. Thanks! — aarelovich, Mar 22 '14 at 19:35

score 15 · Answer 1 · answered Sep 25 '14 at 00:38

This is a pretty common issue with ViewPagers. You need to set an id for your view pager. The documentation states this at the top:

When using FragmentPagerAdapter the host ViewPager must have a valid ID set.

http://developer.android.com/reference/android/support/v4/app/FragmentStatePagerAdapter.html

What is wrong with this code to use a ViewPager?

1 Answers1