android - 背景上的 FragmentStatePagerAdapter IndexOutOfBound

Question

我正在使用扩展 FragmentStatePagerAdapter 的适配器实现动态 viewpager。

每次我的应用程序进入后台时都会崩溃。在 ViewPager 上使用 IndexOutOfBounds:

这是适配器代码:

/**
 * Created by root on 3/11/15.
 */
public class FragmentAdapter extends FragmentStatePagerAdapter {
    private ArrayList<Fragment> mFragList = null;
    private ArrayList<String> mFragmentNameList = null;

    public FragmentAdapter(FragmentManager fm, ArrayList<Fragment> mFragList, ArrayList<String> fragmentNameList) {
        super(fm);
        this.mFragList = mFragList;
        this.mFragmentNameList = fragmentNameList;
    }

    @Override
    public Fragment getItem(int position) {
        if (!AppUtility.isNullOrEmpty(mFragList) && position < mFragList.size()) {
            return mFragList.get(position);
        }
        return null;
    }

    @Override
    public int getCount() {
        if (mFragList != null) {
            return mFragList.size();
        }
        return 0;
    }

    @Override
    public CharSequence getPageTitle(int position) {
        return mFragmentNameList.get(position);
    }
}

这是 fragment 代码:

 public class PagerFragment extends BaseFragment {

        private final int MAX_PAGES = 4;
        private ViewPager mViewPager = null;
        private FragmentAdapter mFragmentAdapter = null;
        private ArrayList<Fragment> mFragList = new ArrayList<>(MAX_PAGES);
        private ArrayList<String> mFragmentNameList = new ArrayList<>(MAX_PAGES);
        private TabLayout mTabLayout = null;



    @Override
    public void onViewCreated(View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        initViewById(view);
    }

    public void initViewById(View view) {
        mViewPager = (ViewPager) view.findViewById(R.id.viewpager);
        mTabLayout = (TabLayout) view.findViewById(R.id.tabs);

        mFragList.add(new Fragment());
        mFragList.add(new Fragment());
        mFragList.add(new Fragment());
        mFragList.add(new Fragment());
        mFragmentNameList.add("Fragment1");
        mFragmentNameList.add("Fragment2");
        mFragmentNameList.add("Fragment3");
        mFragmentNameList.add("Fragment4");
        mFragmentAdapter = new FragmentAdapter(getFragmentManager(), mFragList, mFragmentNameList);
        mViewPager.setOffscreenPageLimit(2);
        mViewPager.setAdapter(mFragmentAdapter);
        mViewPager.setPageTransformer(true, new ZoomOutPageTransformer());
        mTabLayout.setupWithViewPager(mViewPager);
    }
}

它不显示我的类(class)的任何行号，但只显示 viewpager:

错误日志:

FATAL EXCEPTION: main
Process: com.android.myapp.ui, PID: 5897
java.lang.IndexOutOfBoundsException: Invalid index 5, size is 3
  at java.util.ArrayList.throwIndexOutOfBoundsException(ArrayList.java:255)
  at java.util.ArrayList.get(ArrayList.java:308)
  at android.support.v4.view.ViewPager.getChildDrawingOrder(ViewPager.java:800)
  at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3396)
  at android.view.View.draw(View.java:16384)
  at android.support.v4.view.ViewPager.draw(ViewPager.java:2415)
  at android.view.View.updateDisplayListIfDirty(View.java:15378)
  at android.view.View.draw(View.java:16151)
  at android.view.ViewGroup.drawChild(ViewGroup.java:3610)
  at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3400)
  at android.view.View.updateDisplayListIfDirty(View.java:15373)
  at android.view.View.draw(View.java:16151)
  at android.view.ViewGroup.drawChild(ViewGroup.java:3610)
  at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3400)
  at android.view.View.draw(View.java:16384)
  at android.view.View.updateDisplayListIfDirty(View.java:15378)
  at android.view.View.draw(View.java:16151)
  at android.view.ViewGroup.drawChild(ViewGroup.java:3610)
  at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3400)
  at android.view.View.draw(View.java:16384)
  at android.view.View.updateDisplayListIfDirty(View.java:15378)
  at android.view.View.draw(View.java:16151)
  at android.view.ViewGroup.drawChild(ViewGroup.java:3610)
  at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3400)
  at android.view.View.updateDisplayListIfDirty(View.java:15373)
  at android.view.View.draw(View.java:16151)
  at android.view.ViewGroup.drawChild(ViewGroup.java:3610)
  at android.support.v4.widget.DrawerLayout.drawChild(DrawerLayout.java:1383)
  at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3400)
  at android.view.View.draw(View.java:16384)
  at android.view.View.updateDisplayListIfDirty(View.java:15378)
  at android.view.View.draw(View.java:16151)
  at android.view.ViewGroup.drawChild(ViewGroup.java:3610)
  at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3400)
  at android.view.View.updateDisplayListIfDirty(View.java:15373)
  at android.view.View.draw(View.java:16151)
  at android.view.ViewGroup.drawChild(ViewGroup.java:3610)
  at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3400)
  at android.view.View.updateDisplayListIfDirty(View.java:15373)
  at android.view.View.draw(View.java:16151)
  at android.view.ViewGroup.drawChild(ViewGroup.java:3610)
  at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3400)
  at android.view.View.updateDisplayListIfDirty(View.java:15373)
  at android.view.View.draw(View.java:16151)
  at android.view.ViewGroup.drawChild(ViewGroup.java:3610)
  at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3400)
  at android.view.View.updateDisplayListIfDirty(View.java:15373)
  at android.view.View.draw(View.java:16151)
  at android.view.ViewGroup.drawChild(ViewGroup.java:3610)
  at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3400)
  at android.view.View.draw(View.java:16384)
  at com.android.internal.policy.PhoneWindow$DecorView.draw(PhoneWindow.java:2692)
  at android.view.View.updateDisplayListIfDirty(View.java:15378)
  at android.view.ThreadedRenderer.updateViewTreeDisplayList(ThreadedRenderer.java:281)
  at android.view.ThreadedRenderer.updateRootDisplayList(ThreadedRenderer.java:287)
  at android.view.ThreadedRenderer.draw(ThreadedRenderer.java:322)
  at android.view.ViewRootImpl.draw(ViewRootImpl.java:2928)
  at android.view.ViewRootImpl.performDraw(ViewRootImpl.java:2740)
  at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2358)
  at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1233)
  at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6549)
  at android.view.Choreographer$CallbackRecord.run(Choreographer.java:919)
  at android.view.Choreographer.doCallbacks(Choreographer.java:710)
  at android.view.Choreographer.doFrame(Choreographer.java:645)
  at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:905)
    at android.os.Han

Answer 1

好的，我找到了解决方案，基本上问题根本不在适配器中，我将我的 viewPager 放在 fragment 中，为此适配器需要引用 getChildfragmentManager() 而不是 getFragmentManager()；我改变了

mFragmentAdapter = new FragmentAdapter(getFragmentManager(), mFragList, mFragmentNameList);
           to
mFragmentAdapter = new FragmentAdapter(getChildFragmenManager(), mFragList, mFragmentNameList);

Volla 成功了。