在片段中的onCreateView之前调用setUserVisibleHint

Question

@Override
public void setUserVisibleHint(boolean isVisibleToUser) {
    //FIXED: setUserVisibleHint() called before onCreateView() in Fragment causes NullPointerException
    //super.setUserVisibleHint(isVisibleToUser);
}

Answer 1

// create boolean for fetching data
private boolean isViewShown = false;

@Override
public void setUserVisibleHint(boolean isVisibleToUser) {
    super.setUserVisibleHint(isVisibleToUser);
    if (getView() != null) {
        isViewShown = true;
        // fetchdata() contains logic to show data when page is selected mostly asynctask to fill the data
        fetchData();
    } else {
        isViewShown = false;
    }
} 

使用ISViewShower实例变量来决定是在OnCreateView()中还是在SetUserVisibleHint()中提取数据。

下面的代码包含OnCreateView()的逻辑：

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.main_layout, container, false);

   // view initialization steps.......

   if (!isViewShown) {
        fetchData();
   } 
   // do other stuff
}

这段代码会解决你的问题。因为它解决了我的问题。：）