片段以編程方式更改高度

Question

我試圖以編程方式更改片段的高度。

我可以在片段布局高度為650dp的XML中得到結果；

但是我想動態地改變它。

在片段的onCreateView內，我編寫了以下代碼，該代碼引發NullPointerException-

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
    // Inflate the layout for this fragment
    View v = inflater.inflate(R.layout.fragment_group_info, container, false);
    try {
        ViewGroup.LayoutParams params = v.getLayoutParams();
        params.height = 610;
        v.setLayoutParams(params);
    } catch (Exception e) {
        Log.d("ListView1", "GroupInfoFragment Height Exception: " + e.toString());
    }
    mListView = (ListView) v.findViewById(android.R.id.list);
    rv =v;
    return v;
}

例外-

GroupInfo Fragment Height Exception: java.lang.NullPointerException: 
Attempt to invoke virtual method 'android.view.View android.app.Fragment.getView()' 
on a null object reference

Answer 1

初始化全局View（以下rv）變量，並在Fragment onCreateView上初始化-

View rv;
...
...
...


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

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


    rv =v;
    return v;
}

在片段的onActivityCreated方法上更改高度-

@Override
public void onActivityCreated(Bundle savedInstanceState)
{
    super.onActivityCreated(savedInstanceState);
    try {
        ViewGroup.LayoutParams params = rv.getLayoutParams();
        params.height = 1200;
        rv.setLayoutParams(params);
    } catch (Exception e) {
        Log.d("ListView1", "2 GroupInfoFragment Height Exception: " + e.toString());
    }
}