mac android创建activity 空指针,Activity 重新创建时viewpager适配器为空_android-viewpager_开发99编程知识库...

我正在实现包含viewpager的android应用程序。 问题在于在背景中杀死应用程序时，当我在 viewpager onPostExecute方法中设置时，线上有空指针。 下面是我的代码。希望得到帮助：)

fragment 类中发生崩溃的代码段protected void onPostExecute(ArrayList result) {

super.onPostExecute(result);

if (this.fragmentWeakRef.get()!= null) {

if (result!= null) {

mHomeCategories = result;

if(mBannerViewPager!= null){

mBannerViewPager.setAdapter(new BannerViewpagerAdapter(

getChildFragmentManager(), getActivity()

. getApplicationContext()));//here app crashes after being killed in background

//and restored

}

mcategoryViewPager.setAdapter(new CategoryViewpagerAdapter(

getChildFragmentManager(), getActivity()

. getApplicationContext(),setFragmentsArray()));

} else {

Toast.makeText(getActivity().getApplicationContext(),

"No Internet Connection", Toast.LENGTH_SHORT)

. show();

}

}

}

}

这是我的适配器public class BannerViewpagerAdapter extends FragmentPagerAdapter {

private SparseArray registeredFragments = new SparseArray();

private static HashMap myHashmap = new HashMap();

static {

myHashmap.put(0, R.drawable.img);

myHashmap.put(1, R.drawable.stopex);

}

public BannerViewpagerAdapter(android.support.v4.app.FragmentManager fm, Context context) {

super(fm);

//TODO Auto-generated constructor stub

}

@Override

public Fragment getItem(int position) {

//TODO Auto-generated method stub

BannerFragment myFragment = null;

myFragment = registeredFragments.get(position);

if(myFragment == null){

myFragment = BannerFragment.newInstance(myHashmap.get(position));

registeredFragments.put(position, myFragment);

}

return myFragment;

}

@Override

public Object instantiateItem(ViewGroup arg0, int arg1) {

//TODO Auto-generated method stub

return super.instantiateItem(arg0, arg1);

}

@Override

public int getCount() {

//TODO Auto-generated method stub

return 2;

}

}