Question

我是Android开发的新手。我将代码从我的MainActivity转移到了Fragment类。在我的onCreateView方法中，我调用一个viewFunds（）方法来从SQLite动态显示数据。

但是，当我单击该片段的选项卡时，应用程序会在到达removeAllViews行时关闭。每次调用此方法刷新数据时，我都需要先删除AllViews。

由于我也在其他方法中调用ViewFunds（），例如删除数据时，我会调用它来刷新屏幕上的结果。

见下面的代码：

public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

        View rootview = inflater.inflate(R.layout.activity_settings_tab, container, false);
        super.onCreate(savedInstanceState);
        myDb = new DatabaseHelper(getContext());


        btnAddData = (Button) rootview.findViewById(R.id.button_add);
        btnviewAll = (Button) rootview.findViewById(R.id.button_viewAll);
        btnAddFund = (Button) rootview.findViewById(R.id.button_AddFund);
        btnviewUpdate = (Button) rootview.findViewById(R.id.button_update);
        editEmergencyFund = (EditText) rootview.findViewById(R.id.edit_EmergencyFund);
        editProsperityFund = (EditText) rootview.findViewById(R.id.edit_ProsperityFund);
        editRewardFund = (EditText) rootview.findViewById(R.id.edit_RewardFund);

        viewAll(); //this is for a button
        viewFunds();//this is executed when the fragment is called


        return inflater.inflate(R.layout.activity_settings_tab, container, false);
    }


public void viewFunds() { 
        Cursor res2 = myDb.getConfigData();
        res2.moveToFirst();


        final View linearLayout = getActivity().findViewById(R.id.ll_config);
        ((LinearLayout) linearLayout.getParent()).removeAllViews(); //clear layout first - LINE WITH ISSUE
        ((LinearLayout) linearLayout.getParent()).setGravity(Gravity.CENTER);

 //some code follows...

 }

在removeAllViews行之后编写的这组代码中的最后一行也会导致应用程序关闭：

 LinearLayout llh = new LinearLayout(getActivity());
            llh.setOrientation(LinearLayout.HORIZONTAL);
            LinearLayout.LayoutParams lp_llh = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT);
            llh.setLayoutParams(lp_llh);

            ((LinearLayout) linearLayout.getParent()).addView(llh); //code  that causes app to close

提前感谢您的帮助。

Answer 1

我认为((LinearLayout) linearLayout.getParent()).removeAllViews()也会移除linearLayout。试着这样做：

...
ViewParent parent = linearLayout.getParent();
parent.removeAllViews();
parent.setGravity(Gravity.CENTER);
...
parent.addView(llh);
...

Answer 2

在此处，您返回刚刚在View末尾创建的新onCreateView：

return inflater.inflate(R.layout.activity_settings_tab, container, false);

由于您返回的View非Views，因此您找到了有效参考，这会导致NPE。将其更改为：

return rootView;

应用程序关闭在fragmentLayout removeAllViews行内的片段：Android

2 个答案: