java.lang.NullPointerException：空对象引用上的FloatingActionButton.setVisibility（int）'

Question

[我创建了一个Activity，其中包含四个Floating Button和一个片段，该片段调用Activity的Floating Button以使其可见/不可见，但是当我从片段访问这些Floating Buttons时，它将引发空指针异常。

活动代码：

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

    getInitialized();

    fabSettings = (FloatingActionButton) this.findViewById(R.id.fabSetting);
    fabStory = (FloatingActionButton) this.findViewById(R.id.fabStory);
    fabImage = (FloatingActionButton) this.findViewById(R.id.fabImage);
    fabVideo = (FloatingActionButton) this.findViewById(R.id.fabVideo);

}

片段代码：

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

    View v = inflater.inflate(R.layout.fragment_all_community, container, false);


    SessionManager sessionManager = new SessionManager(getActivity());
    if(sessionManager.isLoggedIn()){


        ActivityUser.fabSettings.setVisibility(View.VISIBLE);
        ActivityUser.laySearchCode.setVisibility(View.VISIBLE);
        ActivityUser.bottomLayout.setVisibility(View.VISIBLE);

        tvCreateCommunity.setVisibility(View.VISIBLE);
    }else{
        MainActivity.fabSettings.setVisibility(View.VISIBLE);
        MainActivity.bottomLayout.setVisibility(View.VISIBLE);
        MainActivity.laySearchCode.setVisibility(View.VISIBLE);
        ((MainActivity) getActivity()).getSupportActionBar().setTitle("");
        tvCreateCommunity.setVisibility(View.GONE);
    }
 }

请帮助

Answer 1

使用此代码

片段：