类内的getFragmentManager()

Question

我正在尝试在类中获取FragmentManager 以显示我的dialogFragment，但它抛出错误...：

java.lang.ClassCastException: example.MyApplication 无法转换为 android.app.Activity

这是我的完整课程：

public class ExpandableListAdapter extends BaseExpandableListAdapter {

private Context _context;
private List<String> _listDataHeader; // header titles
// child data in format of header title, child title
private HashMap<String, List<String>> _listDataChild;
private static final String TAG = "ExpandableListAdapter";
Activity activity;

public ExpandableListAdapter(Context context, List<String> listDataHeader,
                             HashMap<String, List<String>> listChildData) {
    this._context = context;
    this._listDataHeader = listDataHeader;
    this._listDataChild = listChildData;

}

@Override
public Object getChild(int groupPosition, int childPosititon) {
    return this._listDataChild.get(this._listDataHeader.get(groupPosition))
            .get(childPosititon);
}

@Override
public long getChildId(int groupPosition, int childPosition) {
    return childPosition;
}

@Override
public View getChildView(int groupPosition, final int childPosition,
                         boolean isLastChild, View convertView, ViewGroup parent) {

    final String childText = (String) getChild(groupPosition, childPosition);

    if (convertView == null) {
        LayoutInflater infalInflater = (LayoutInflater) this._context
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        convertView = infalInflater.inflate(R.layout.list_item, null);
    }

    TextView txtListChild = (TextView) convertView
            .findViewById(R.id.viewEmployee);


    txtListChild.setText(childText);
    return convertView;
}

@Override
public int getChildrenCount(int groupPosition) {
    return this._listDataChild.get(this._listDataHeader.get(groupPosition))
            .size();
}

@Override
public Object getGroup(int groupPosition) {
    return this._listDataHeader.get(groupPosition);
}

@Override
public int getGroupCount() {
    return this._listDataHeader.size();
}

@Override
public long getGroupId(int groupPosition) {
    return groupPosition;
}

@Override
public View getGroupView(int groupPosition, boolean isExpanded,
                         View convertView, ViewGroup parent) {
    String headerTitle = (String) getGroup(groupPosition);
    if (convertView == null) {
        LayoutInflater infalInflater = (LayoutInflater) this._context
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        convertView = infalInflater.inflate(R.layout.list_group, null);
    }

    TextView lblListHeader = (TextView) convertView
            .findViewById(R.id.employeeType);
    TextView addEmpolyee = (TextView) convertView.findViewById(R.id.addEmployee); 
    addEmpolyee.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            activity = (Activity) _context;
            DataEntryEmpolyee empolyee = new DataEntryEmpolyee();
            empolyee.show(activity.getFragmentManager(), "DIALOG_FRAGMENT");
        }
    });

    lblListHeader.setTypeface(null, Typeface.BOLD);
    lblListHeader.setText(headerTitle);

    return convertView;
}

@Override
public boolean hasStableIds() {
    return false;
}

@Override
public boolean isChildSelectable(int groupPosition, int childPosition) {
    return true;
}

}

Answer 1

您可能在适配器中传递了错误的上下文。在应用程序上下文中使用活动的上下文。

活动中

 new ExpandableListAdapter(YourActivity.this,yourList,yourHashMap);

在片段中

 new ExpandableListAdapter(getActivity(),yourList,yourHashMap);

Answer 2

尝试用 YourActivity.this 或 getContext() 或 getActivity() 替换 getApplicationContext，具体取决于您在其中创建适配器对象的类。

例如

new ExpandableListAdapter(YourActivity.this, listDataHeader, listChildData);