错误：可扩展列表视图的表达式

Question

实际上，每当我点击其中一个按钮时，我都会尝试获取所选项目的消耗列表视图。但是在我编写代码之后，它显示了表达式。你可以建议

提前致谢。

public class UploadPageActivity extends Activity {

ExpandableListAdapter listAdapter;
ExpandableListView expListView;
List<String> listDataHeader;
HashMap<String, List<String>> listDataChild;
Button mupload;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_upload);
    mupload = (Button)findViewById(R.id.upload_btn);

    Fragment main = new MainFragment();
    FragmentTransaction ft = getFragmentManager().beginTransaction();
    ft.replace(R.id.content_frame, main);
    ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE);
    ft.addToBackStack(null);
    ft.commit();

    // get the listview
    expListView = (ExpandableListView) findViewById(R.id.lvExp);

    ArrayAdapter<String>adapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_multiple_choice,
            (List<String>) listDataChild);
    expListView.setChoiceMode(expListView.CHOICE_MODE_MULTIPLE);
    expListView.setAdapter(ExpandableListAdapter);

    mupload.setOnClickListener(new Button.OnClickListener() {
        @Override
        public void onClick(View v) {

            String selected = "";

            int cntChoice = expListView.getCount();
            SparseBooleanArray sparseBooleanArray = expListView.getCheckedItemPositions();
            for (int i = 0; i < cntChoice; i++) {
                if (sparseBooleanArray.get(i)) {
                    selected += expListView.getItemAtPosition(i).toString() + "\n";
                }
            }
            Toast.makeText(UploadPageActivity.this, selected,
                    Toast.LENGTH_LONG).show();
        }});

ExpandableListAdapter：

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;

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

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

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

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

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

@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_retailorslist, null);
    }

    TextView lblListHeader = (TextView) convertView
            .findViewById(R.id.lblListHeader);
    lblListHeader.setTypeface(null, Typeface.BOLD);
    lblListHeader.setText(headerTitle);

    return convertView;
}

@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_retailoritems, null);
    }

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

    txtListChild.setText(childText);
    return convertView;
}

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

}