Question

我有一个由ViewPager托管的片段

public class FragmentOne extends Fragment {

DatabaseHelper db;
String TAG = "FragmentOne";
DisplayActivity displayActivity;
....
@Override
public void onActivityCreated(@Nullable Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);
    displayActivity = new DisplayActivity();
    initView();
}
    Button delete = (Button) getActivity().findViewById(R.id.dont);
    delete.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            displayActivity.removeCurrentFragment(count-1);


        }
    });

我的目标是从ViewPager中删除此当前片段。但是，通过调试器，我发现displayActivity为null。

如何获取displayActivity的参考资料？

public class DisplayActivity extends FragmentActivity {

ViewPager viewPager;
PagerAdapter pagerAdapter;
String TAG = "DisplayActivity";


public void removeCurrentFragment(int position){
    pagerAdapter.fragmentArrayList.remove(position);
    pagerAdapter.notifyChangeInPosition(1);
    pagerAdapter.notifyDataSetChanged();
    Log.e(TAG, "in removeCurrentFragment");
}

我尝试使用displayActivity = new DisplayActivity（）; 但似乎没有用。

这是错误

NullPointerException: Attempt to invoke virtual method 'void .DisplayActivity.removeCurrentFragment(int)' on a null object reference

Answer 1

将getActivity()与强制转换为DisplayActivity。

public void onActivityCreated(@Nullable Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);
    displayActivity = (DisplayActivity) getActivity();
    initView();
}

在片段中，无法获得对托管活动的引用

1 个答案: