ExpandableListView不显示任何东西

Question

没有错误，没有警告，它编译成功，但我的ExpandableListView没有显示任何东西。 这里是我ExpandableListViewAdapter类：

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 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.lblListItem); 

    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.lblListHeader); 
    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; 
} 


} 

这里是我ListViewtest类：

public class ListViewTest extends AppCompatActivity { 

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


@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 


    // get the listview 
    // expListView = (ExpandableListView) findViewById(R.id.lvExp); 
    View explist = getLayoutInflater().inflate(R.layout.activity_expandable_list,null,false); 
    expListView = (ExpandableListView) explist.findViewById(R.id.lvExp); 
    // preparing list data 
    prepareListData(); 

    listAdapter = new ExpandableListAdapter(this, listDataHeader, listDataChild); 



    // setting list adapter 
    expListView.setAdapter(listAdapter); 
    setContentView(R.layout.activity_expandable_list); 

} 

/* 
* Preparing the list data 
*/ 
private void prepareListData() { 
    listDataHeader = new ArrayList<String>(); 
    listDataChild = new HashMap<String, List<String>>(); 

    // Adding child data 
    listDataHeader.add("Top 250"); 
    listDataHeader.add("Now Showing"); 
    listDataHeader.add("Coming Soon.."); 

    // Adding child data 
    List<String> top250 = new ArrayList<String>(); 
    top250.add("The Shawshank Redemption"); 
    top250.add("The Godfather"); 
    top250.add("The Godfather: Part II"); 
    top250.add("Pulp Fiction"); 
    top250.add("The Good, the Bad and the Ugly"); 
    top250.add("The Dark Knight"); 
    top250.add("12 Angry Men"); 

    List<String> nowShowing = new ArrayList<String>(); 
    nowShowing.add("The Conjuring"); 
    nowShowing.add("Despicable Me 2"); 
    nowShowing.add("Turbo"); 
    nowShowing.add("Grown Ups 2"); 
    nowShowing.add("Red 2"); 
    nowShowing.add("The Wolverine"); 

    List<String> comingSoon = new ArrayList<String>(); 
    comingSoon.add("2 Guns"); 
    comingSoon.add("The Smurfs 2"); 
    comingSoon.add("The Spectacular Now"); 
    comingSoon.add("The Canyons"); 
    comingSoon.add("Europa Report"); 

    listDataChild.put(listDataHeader.get(0), top250); // Header, Child data 
    listDataChild.put(listDataHeader.get(1), nowShowing); 
    listDataChild.put(listDataHeader.get(2), comingSoon); 
} 

我不知道我做错了。任何人都可以告诉我我的问题在哪里？先谢谢你。

Answer 1

您可以通过调用这个覆盖所有布局的变化：

setContentView(R.layout.activity_expandable_list); 

这可能会解决问题：

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_expandable_list); 

    // get the listview 
    expListView = (ExpandableListView) findViewById(R.id.lvExp); 
    // preparing list data 
    prepareListData(); 

    listAdapter = new ExpandableListAdapter(this, listDataHeader, listDataChild); 



    // setting list adapter 
    expListView.setAdapter(listAdapter); 
}