I'm trying to write a simple example which pulls external data over the network and populates an ExpandableListView via a ExpandableListAdapter. I've tried a couple examples and am pretty much lost. I'm familiar with working with the ArrayAdapter class, but it seems that ExpandableListAdapter is WAY different. Here is my current application code that is displaying nothing:
MyExpandableListAdapter:
public class MyExpandableListAdapter extends BaseExpandableListAdapter {
public static class GroupHolder {
TextView title;
}
public static class ChildHolder {
TextView title;
ImageView icon;
}
// groups.getChildren() returns the children
private List<Group> groups;
private Context context;
private LayoutInflater inflater;
public MyExpandableListAdapter(Context context, List<Group> groups) {
this.context = context;
this.groups = groups;
this.inflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
public boolean hasStableIds() {
return true;
}
public Object getGroup(int groupPosition) {
return groups.get(groupPosition);
}
public int getGroupCount() {
return groups.size();
}
public long getGroupId(int groupPosition) {
return groupPosition;
}
public View getGroupView(int groupPosition, boolean isExpanded,
View convertView, ViewGroup parent) {
GroupHolder holder;
if (convertView != null) {
holder = (GroupHolder)convertView.getTag();
} else {
convertView = inflater.inflate(R.layout.group_item, parent, false);
holder = new GroupHolder();
holder.title = (TextView) convertView.findViewById(R.id.group_item_title);
convertView.setTag(holder);
}
holder.title.setText(this.groups.get(groupPosition).getName());
return convertView;
}
public boolean isChildSelectable(int groupPosition, int childPosition) {
return true;
}
public Object getChild(int groupPosition, int childPosition) {
return groups.get(groupPosition).getChildren().get(childPosition);
}
public long getChildId(int groupPosition, int childPosition) {
return childPosition;
}
public int getChildrenCount(int groupPosition) {
return groups.get(groupPosition).getChildren().size();
}
public View getChildView(int groupPosition, int childPosition,
boolean isLastChild, View convertView, ViewGroup parent) {
ChildHolder holder;
if (convertView != null) {
holder = (ChildHolder) convertView.getTag();
} else {
convertView = inflater.inflate(R.layout.child_item, parent, false);
holder = new ChildHolder();
holder.title = (TextView) convertView.findViewById(R.id.child_item_title);
holder.icon = (ImageView) convertView.findViewById(R.id.child_item_icon);
convertView.setTag(holder);
}
holder.title.setText(groups.get(groupPosition).getChildren().get(childPosition).getName());
// TODO add in image loading.
return convertView;
}
}
MyExpandableListActivity:
public class MyExpandableListActivity extends ExpandableListActivity {
private List<Group> groups;
private ExpandableListAdapter adapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.group_list);
this.groups = new ArrayList<Group>();
Group group = new Group("$1", "Colors");
Child child = new Child("$2", "Red");
groups.getChildren().add(child);
this.adapter = new MyExpandableListAdapter(this, groups);
setListAdapter(this.adapter);
}
}
R.layout.group_list:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<ExpandableListView android:id="@+id/android:list"
android:layout_width="fill_parent"
android:layout_height="fill_parent"/>
<TextView android:id="@+id/android:empty"
android:text="EMPTY! DOOM!"
android:layout_width="fill_parent"
android:layout_height="fill_parent"/>
</LinearLayout>
R.layout.group_item:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView android:id="@+id/group_item_title"/>
</LinearLayout>
R.layout.child_item:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal">
<ImageView android:id="@+id/child_item_icon"
android:layout_width="48px" android:layout_height="48px"/>
<TextView android:id="@+id/child_item_title"/>
</LinearLayout>
I, of course, am seeing "EMPTY! DOOM!" rather than the list item I added in my activity. What am I doing wrong?
Also, it seems that the SimpleExpandableListAdapter is supposed to make things easy, but I totally can't figure out how it works or how to use it. Can anyone help me figure this out?
