Issue with Expanding Multi-Level ExpandableListView
I have a multi level (3 levels, Root -> Parent -> Child) ExpandableListView containing children that are also ExpandableListViews. I'm having no issue filling them up; however, I need to expand a specific item in the Parent level when I first display the Activity (onCreate).
I successfully expand the related Root item of the Parent but I can't seem to expand the Parent item. The given listeners are called and yet the result isn't reflected in my multi level list.
Activity in which I call the expansion:
public class Activity {
private int groupToExpand = 4, childToExpand = 3;
protected void onCreate(Bundle savedInstance) {
final ExpandableListView elv = (ExpandableListView) findViewById(R.id.elv);
if (arrayList!= null && !arrayList.isEmpty()) {
elv.setAdapter(new RootAdapter(this, arrayList);
// this selects the correct group, but doesn't expand the child.
elv.setSelectedChild(groupToExpand, childToExpand, true);
elv.expandGroup(groupToExpand); // this works.
}
}
}
My Root adapter:
public class RootAdapter extends BaseExpandableListAdapter {
private List<Objects> arrayList;
private Context context;
private LayoutInflater inflater;
public RootAdapter(Context context, List<Objects> arrayList) {
this.context = context;
this.arrayList = arrayList;
this.inflater = LayoutInflater.from(context);
}
@Override
public Object getChild(int groupPosition, int childPosition) {
final Objects parent = (Objects) getGroup(groupPosition);
return parent.arrayList.get(childPosition);
}
@Override
public long getChildId(int groupPosition, int childPosition) {
return childPosition;
}
@Override
public View getChildView(int groupPosition, int childPosition,
boolean isLastChild, View convertView, ViewGroup parent) {
final Objects o = (Objects) getChild(groupPosition, childPosition);
CustomExpandableListView elv = (CustomExpandableListView) convertView;
ChildViewHolder holder;
if (elv == null) {
holder = new ChildViewHolder();
elv = new CustomExpandableListView(context);
elv.setGroupIndicator(null);
elv.setDivider(null);
elv.setCacheColorHint(Color.parseColor("#00000000"));
elv.setChildDivider(null);
elv.setChildIndicator(null);
elv.setScrollingCacheEnabled(false);
elv.setAnimationCacheEnabled(false);
holder.cListView = elv;
elv.setTag(holder);
} else {
holder = (ChildViewHolder) elv.getTag();
}
final ParentAdapter adapter = new ParentAdapter(context, o);
holder.cListView.setAdapter(adapter);
return elv;
}
private static class ChildViewHolder {
CustomExpandableListView cListView;
}
@Override
public int getChildrenCount(int groupPosition) {
final Objects parent = (Objects) getGroup(groupPosition);
return parent.arrayList.size();
}
@Override
public Object getGroup(int groupPosition) {
return arrayList.get(groupPosition);
}
@Override
public int getGroupCount() {
return arrayList.size();
}
@Override
public long getGroupId(int groupPosition) {
return groupPosition;
}
@Override
public View getGroupView(int groupPosition, boolean isExpanded,
View convertView, ViewGroup parent) {
View layout = convertView;
GroupViewHolder holder;
final Objects o = (Objects) getGroup(groupPosition);
if (layout == null) {
layout = inflater.inflate(R.layout.item_to_inflate, parent, false);
holder = new GroupViewHolder();
holder.title = (TextView) layout.findViewById(R.id.title);
holder.image = (ImageView) layout.findViewById(R.id.image);
layout.setTag(holder);
} else {
holder = (GroupViewHolder) layout.getTag();
}
holder.title.setText(o.title.trim());
return layout;
}
@Override
public boolean hasStableIds() {
return true;
}
@Override
public boolean isChildSelectable(int groupPosition, int childPosition) {
return true;
}
private static class GroupViewHolder {
TextView title;
ImageView image;
}
public class CustomExpandableListView extends ExpandableListView {
public CustomExpandableListView(Context context) {
super(context);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
heightMeasureSpec = MeasureSpec.makeMeasureSpec(2000, MeasureSpec.AT_MOST);
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
}
}
Finally my ParentAdapter :
public class ParentAdapter extends BaseExpandableListAdapter {
private Objects child;
private LayoutInflater inflater;
public ParentAdapter(Context context, Objects child) {
this.child = child;
this.inflater = LayoutInflater.from(context);
}
@Override
public Object getChild(int groupPosition, int childPosition) {
return child.arrayList.get(childPosition);
}
@Override
public long getChildId(int groupPosition, int childPosition) {
return childPosition;
}
@Override
public View getChildView(int groupPosition, int childPosition,
boolean isLastChild, View convertView, ViewGroup parent) {
View layout = convertView;
final Objects o = (Objects) getChild(0, childPosition);
ChildViewHolder holder;
if (layout == null) {
layout = inflater.inflate(R.layout.item_to_inflate, parent, false);
holder = new ChildViewHolder();
holder.title = (TextView) layout.findViewById(R.id.title);
layout.setTag(holder);
} else {
holder = (ChildViewHolder) layout.getTag();
}
holder.title.setText(o.title.trim());
return layout;
}
@Override
public int getChildrenCount(int groupPosition) {
return child.arrayList.size();
}
@Override
public Object getGroup(int groupPosition) {
return child;
}
@Override
public int getGroupCount() {
return 1;
}
@Override
public long getGroupId(int groupPosition) {
return groupPosition;
}
@Override
public View getGroupView(int groupPosition, boolean isExpanded,
View convertView, ViewGroup parent) {
View layout = convertView;
GroupViewHolder holder;
if (layout == null) {
layout = inflater.inflate(R.layout.item_to_inflate, parent, false);
holder = new GroupViewHolder();
holder.image = (ImageView) layout.findViewById(R.id.image);
holder.title = (TextView) layout.findViewById(R.id.title);
layout.setTag(holder);
} else {
holder = (GroupViewHolder) layout.getTag();
}
holder.title.setText(o.title.trim());
return layout;
}
@Override
public boolean hasStableIds() {
return true;
}
@Override
public boolean isChildSelectable(int groupPosition, int childPosition) {
return true;
}
private static class GroupViewHolder {
TextView title;
ImageView image;
}
private static class ChildViewHolder {
TextView title;
}
}
I can't expand the child lists within the root ExpandableListView; do you know any correct way to expand the items at the Parent level?
I tried in getChildView of the RootAdapter :
if (groupToExpand == groupPosition && childToExpand == childPosition) {
elv.expandGroup(childToExpand);
}
Then in the activity i changed:
if (arrayList!= null && !arrayList.isEmpty()) {
RootAdapter adapter = new RootAdapter(this, arrayList);
elv.setAdapter(adapter);
// this selects the correct group, but doesn't expand the child.
elv.setSelectedChild(groupToExpand, childToExpand, true);
elv.expandGroup(groupToExpand); // this works.
adapter.groupToExpand = groupToExpand;
adapter.childToExpand = childToExpand;
adapter.notifyDataSetChanged();
}
This expands the Parent level item, BUT, it generates duplicate items of the Parent. How do I do this correctly? Is this the correct way but my adapter is broken, therefore generating duplicate items?
I just can't find what I'm missing here...
Answer
I ended up using a multi level ExpandableListView adapter from another post in stackoverflow. Unfortunately I just can't find the link anymore so I'll just post my code here.
Top Level of the ExpandableListView adapter.
RootAdapter.java:
public class RootAdapter extends BaseExpandableListAdapter {
private Object root;
private final LayoutInflater inflater;
public class Entry {
public final CustExpListview cls;
public final SecondLevelAdapter sadpt;
public Entry(CustExpListview cls, SecondLevelAdapter sadpt) {
this.cls = cls;
this.sadpt = sadpt;
}
}
public Entry[] lsfirst;
// you can change the constructor depending on which listeners you wan't to use.
public RootAdapter(Context context, Object root, ExpandableListView.OnGroupClickListener grpLst,
ExpandableListView.OnChildClickListener childLst, ExpandableListView.OnGroupExpandListener grpExpLst) {
this.root = root;
this.inflater = LayoutInflater.from(context);
lsfirst = new Entry[root.children.size()];
for (int i = 0; i < root.children.size(); i++) {
final CustExpListview celv = new CustExpListview(context);
SecondLevelAdapter adp = new SecondLevelAdapter(root.children.get(i));
celv.setAdapter(adp);
celv.setGroupIndicator(null);
celv.setOnChildClickListener(childLst);
celv.setOnGroupClickListener(grpLst);
celv.setOnGroupExpandListener(grpExpLst);
lsfirst[i] = new Entry(celv, adp);
}
}
@Override
public Object getChild(int groupPosition, int childPosition) {
return childPosition;
}
@Override
public long getChildId(int groupPosition, int childPosition) {
return childPosition;
}
@Override
public View getChildView(int groupPosition, int childPosition, boolean isLastChild,
View convertView, ViewGroup parent) {
// second level list
return lsfirst[groupPosition].cls;
}
@Override
public int getChildrenCount(int groupPosition) {
return 1;
}
@Override
public Object getGroup(int groupPosition) {
return root.children.get(groupPosition);
}
@Override
public int getGroupCount() {
return root.children.size();
}
@Override
public long getGroupId(int groupPosition) {
return groupPosition;
}
@Override
public View getGroupView(int groupPosition, boolean isExpanded, View convertView,
ViewGroup parent) {
// first level
View layout = convertView;
GroupViewHolder holder;
final Object item = (Object) getGroup(groupPosition);
if (layout == null) {
layout = inflater.inflate(R.layout.item_root, parent, false);
holder = new GroupViewHolder();
holder.title = (TextView) layout.findViewById(R.id.itemRootTitle);
layout.setTag(holder);
} else {
holder = (GroupViewHolder) layout.getTag();
}
holder.title.setText(item.title.trim());
return layout;
}
private static class GroupViewHolder {
TextView title;
}
@Override
public boolean hasStableIds() {
return true;
}
@Override
public boolean isChildSelectable(int groupPosition, int childPosition) {
return true;
}
}
Custom ExpandableListView with the solution to items sometimes not being displayed. There is also a workaround to a known bug for IllegalArgumentException being called when destroying the view (by pressing the back button essentially).
CustExpListview.java:
public class CustExpListview extends ExpandableListView {
public CustExpListview(Context context) {
super(context);
}
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
// the value (2000) should not be fixed and be calculated
// as follows: cell_height x root_items_count x root_items_children_count
heightMeasureSpec = MeasureSpec.makeMeasureSpec(2000, MeasureSpec.AT_MOST);
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
@Override
protected void onDetachedFromWindow() {
try {
super.onDetachedFromWindow();
} catch (IllegalArgumentException e) {
// TODO: Workaround for http://code.google.com/p/android/issues/detail?id=22751
}
}
}
Finally, the code to the last level adapter.
public class SecondLevelAdapter extends BaseExpandableListAdapter {
public Object child;
public SecondLevelAdapter(Object child) {
this.child = child;
}
@Override
public Object getChild(int groupPosition, int childPosition) {
return child.children.get(groupPosition).children.get(childPosition);
}
@Override
public long getChildId(int groupPosition, int childPosition) {
return childPosition;
}
// third level
@Override
public View getChildView(int groupPosition, int childPosition, boolean isLastChild,
View convertView, ViewGroup parent) {
View layout = convertView;
final Object item = (Object) getChild(groupPosition, childPosition);
ChildViewHolder holder;
if (layout == null) {
layout = inflater.inflate(R.layout.item_child, parent, false);
holder = new ChildViewHolder();
holder.title = (TextView) layout.findViewById(R.id.itemChildTitle);
layout.setTag(holder);
} else {
holder = (ChildViewHolder) layout.getTag();
}
holder.title.setText(item.title.trim());
return layout;
}
@Override
public int getChildrenCount(int groupPosition) {
return child.children.get(groupPosition).children.size();
}
@Override
public Object getGroup(int groupPosition) {
return child.children.get(groupPosition);
}
@Override
public int getGroupCount() {
return child.children.size();
}
@Override
public long getGroupId(int groupPosition) {
return groupPosition;
}
// Second level
@Override
public View getGroupView(int groupPosition, boolean isExpanded, View convertView,
ViewGroup parent) {
View layout = convertView;
ViewHolder holder;
final Object item = (Object) getGroup(groupPosition);
if (layout == null) {
layout = inflater.inflate(R.layout.item_parent, parent, false);
holder = new ViewHolder();
holder.title = (TextView) layout.findViewById(R.id.itemParentTitle);
layout.setTag(holder);
} else {
holder = (ViewHolder) layout.getTag();
}
holder.title.setText(item.title.trim());
return layout;
}
@Override
public void registerDataSetObserver(DataSetObserver observer) {
super.registerDataSetObserver(observer);
}
@Override
public void unregisterDataSetObserver(DataSetObserver observer) {
Log.d("SecondLevelAdapter", "Unregistering observer");
if (observer != null) {
super.unregisterDataSetObserver(observer);
}
}
@Override
public boolean hasStableIds() {
return true;
}
@Override
public boolean isChildSelectable(int groupPosition, int childPosition) {
return true;
}
private static class ViewHolder {
TextView title;
}
private static class ChildViewHolder {
TextView title;
}
}
I hope this helps!!!
Update
This is an example of how I call the above adapter.
MainActivity:
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
final List<Object> objects = yourItems;
if (!objects.isEmpty()) {
final ExpandableListView elv = (ExpandableListView) findViewById(R.id.yourExpandableListView);
/* Item click listeners below */
// First level items in the ExpandableListView
elv.setOnGroupClickListener(new ExpandableListView.OnGroupClickListener() {
@Override
public boolean onGroupClick(ExpandableListView eListView, View view, int groupPosition,
long id) {
// TODO: whatever you need
return false /* or true depending on what you need */;
}
});
// Second level items in the ExpandableListView
ExpandableListView.OnGroupClickListener grpLst = new ExpandableListView.OnGroupClickListener() {
@Override
public boolean onGroupClick(ExpandableListView eListView, View view, int groupPosition,
long id) {
// TODO: whatever you need
return false /* or true depending on what you need */;
}
};
// Third (and last) level items in the ExpandableListView
ExpandableListView.OnChildClickListener childLst = new ExpandableListView.OnChildClickListener() {
@Override
public boolean onChildClick(ExpandableListView eListView, View view, int groupPosition,
int childPosition, long id) {
// TODO: whatever you need
return false /* or true depending on what you need */;
}
};
ExpandableListView.OnGroupExpandListener grpExpLst = new ExpandableListView.OnGroupExpandListener() {
@Override
public void onGroupExpand(int groupPosition) {
/* this one is not required of course, you can delete it from the RootAdapter Constructor
* it is just an example as to how to implement Listeners on the second level items */
}
};
final RootAdapter adapter = new RootAdapter(this, objects, grpLst, childLst, grpExpLst);
elv.setAdapter(adapter);
}
}
This is how my class Object would look like.
Object.java:
public class Object {
public String title; // use getters and setters instead
public List<Object> children; // same as above
public Object() {
children = new ArrayList<Object>();
}
}