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Empty ViewPager view with PagerTabStrip

When used ViewPagerwith PagerTabStrip:

<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.view.ViewPager
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/pager"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent">

<android.support.v4.view.PagerTabStrip
    android:id="@+id/pager_tab_strip"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_gravity="top"
    android:paddingTop="4dp"
    android:paddingBottom="4dp"
    />

</android.support.v4.view.ViewPager>

with a pager having an empty adapter:

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

    ViewPager pager = (ViewPager) findViewById(R.id.pager);

    FragmentPagerAdapter adapter = new FragmentPagerAdapter(getFragmentManager()) {

        @Override
        public CharSequence getPageTitle(int position) {
            return "test";
        }

        @Override
        public Fragment getItem(int i) {
            return null;
        }

        @Override
        public int getCount() {
            return 0;
        }
    };
    pager.setAdapter(adapter);

}

Application crash when touching / scrolling tab strip:

java.lang.IndexOutOfBoundsException: Invalid index 0, size is 0
        at java.util.ArrayList.throwIndexOutOfBoundsException(ArrayList.java:251)
        at java.util.ArrayList.get(ArrayList.java:304)
        at android.support.v4.view.ViewPager.performDrag(ViewPager.java:1990)

I think this line inViewPager.performDrag() may be the reason.

Is this a bug or is there something wrong with my view setting?

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2 answers

In ViewPagercode , array elements are available without any checks (when there is no page):

final ItemInfo firstItem = mItems.get(0);
final ItemInfo lastItem = mItems.get(mItems.size() - 1);

This leads to a failure.

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This error is still not fixed since I encountered the same problem. The problem is that these are two lines in the ViewPager class for Android, in the performDrag (float x) method:

final ItemInfo firstItem = mItems.get(0);
final ItemInfo lastItem = mItems.get(mItems.size() - 1);

, mItems Arraylist . Android...

, . , ViewPager , try catch:

public class CustomViewPager extends ViewPager {

    public CustomViewPager(Context context) {
        super(context);
    }

    public CustomViewPager(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev) {
        boolean event = false;
        try {
            event = super.onInterceptTouchEvent(ev);
        } catch (Exception e) {
            Log.e(MainActivity.TAG, "ERROR: ViewPagerAdapter was empty");
        }
        return event;
    }
}

, try, catch , , , .

EDIT:

ViewPager XML:

<com.package.CustomViewPager
    android:id="@+id/viewPager_fragment_container"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content">

    <android.support.v4.view.PagerTabStrip
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
</com.package.CustomViewPager>
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