Android expandable list view fragment

Question

I am in search of implementing fragments with expandable list view . After searching i found a class that implements expandable listview fragment on https://gist.github.com/1316903 . But i have no idea how to use it. Please help me. I tried list fragments ,but i have no idea about using fragments with expandable list view thanks in advance.

Answer 1

Here is what I got in MonoDroid/C#. I had to strip away some code (for confidentiality), but it should be mostly complete.

This implementation can support distinct child-views, where each group contains a specific child-type that is the same throughout that group. However, you can mix child-types within a group, and can even have different group-types (which just changes the group header really; I use the same group-type for both groups, and use the group's position to determine the child-type - so group[0] contains children of ExpandableListChild1 and group[1] of ExpandableListChild2 - as is the intended use).

The child-types here only differ by their background color (for simplicity's sake), however these views can be any view you require, including custom views. Just make a corresponding ExpandListChild subclass for whatever view you need. Also, the base class ExpandListChildAbs can be whatever you need to suit your app. If you only have one child type, a base class isn't necessary, however if there are two or more then you need some sort of base class both children-types can subclass from to support the polymorphism within the BaseExpandableListAdapter method getChild and related methods.

[Activity(
    Label = "ExpandableListView in a Fragment", 
    Theme = "@android:style/Theme.NoTitleBar", 
    MainLauncher = false,
    ConfigurationChanges = ConfigChanges.KeyboardHidden,
    WindowSoftInputMode = SoftInput.AdjustPan | SoftInput.StateHidden)] 

public class Fragment1 : Fragment
{
    private ViewGroup _thisView;       

    private Bundle _bundle;
    private LayoutInflater _inflater;
    private ViewGroup _container;

    public override void OnCreate(Bundle bundle)
    {
        base.OnCreate(bundle);          

        _bundle = bundle;
        _model = Model;
    }

    public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle bundle)
    {
        base.OnCreateView(inflater, container, bundle);

        _inflater = inflater;
        _container = container;
        _bundle = bundle;

         Render();

        return _thisView;
    }        

    public override void OnAttach(Activity activity)
    {
        base.OnAttach(activity);

        _dialogListener = (IDialogWindow)activity;
    }                

    //public Context LocalContext { get; set; }

    public override void OnActivityCreated(Bundle savedInstanceState)
    {
        base.OnActivityCreated(savedInstanceState);            
    }

    public override void OnViewCreated(View view, Bundle savedInstanceState)
    {
        base.OnViewCreated(view, savedInstanceState);            
    }

    public override void Render()
    {   
        _thisView = (ViewGroup)_inflater.Inflate(Resource.Layout.MainLayout, _container, false);

        ExpandableListView elvParcelInfo = _thisView.FindViewById<ExpandableListView>(Resource.Id.elv_parcel_info);
        List<ExpandListGroup> expandListItems = SetStandardGroups();
        ExpandListAdapter expandListAdapter = new ExpandListAdapter(Activity.ApplicationContext, expandListItems);
        elvParcelInfo.SetAdapter(expandListAdapter);
    }

    public List<ExpandListGroup> SetStandardGroups()
    {
        List<ExpandListChild1> childern1 = new List<ExpandListChild1>();

        for (int i = 0; i < 20; i++)
        {
            ExpandListChild1 child1 = new ExpandListChild1();
            child1.Name = "child1 #" + i.ToString();
            child1.Tag = null;

            childern1.Add(child1);
        }

        ExpandListGroup group1 = new ExpandListGroup();
        group1.Name = "Comedy";
        //group1.Items = childern1;
        group1.Items = new List<ExpandListChildAbs>();
        foreach (ExpandListChild1 child1 in childern1)
        {
            group1.Items.Add(child1);
        }

        /////////////////////////////////////////////////////////////

        List<ExpandListChild2> childern2 = new List<ExpandListChild2>();

        for (int i = 0; i < 20; i++)
        {
            ExpandListChild2 child2 = new ExpandListChild2();
            child2.Name = "child2 #" + i.ToString();
            child2.Tag = null;

            childern2.Add(child2);
        }

        ExpandListGroup group2 = new ExpandListGroup();
        group2.Name = "Action";
        //group2.Items = childern2;
        group2.Items = new List<ExpandListChildAbs>();
        foreach (ExpandListChild2 child2 in childern2)
        {
            group2.Items.Add(child2);
        }

        /////////////////////////////////////////////////////////////

        List<ExpandListGroup> groups = new List<ExpandListGroup>();
        groups.Add(group1);
        groups.Add(group2);

        return groups;
    }

    public abstract class ExpandListChildAbs : Java.Lang.Object
    {
        public abstract String Name { get; set; }
        public abstract String Tag { get; set; }
    }

    public class ExpandListChild1 : ExpandListChildAbs
    {
        public override String Name { get; set; }
        public override String Tag { get; set; }
    }

    public class ExpandListChild2 : ExpandListChildAbs
    {
        public override String Name { get; set; }
        public override String Tag { get; set; }
    }

    public class ExpandListGroup : Java.Lang.Object
    {
        public String Name { get; set; }
        public List<ExpandListChildAbs> Items { get; set; }
    }

    public class ExpandListAdapter : BaseExpandableListAdapter
    {
        private enum ChildTypes { ChildType1, ChildType2 }
        private Context context;
        private List<ExpandListGroup> groups;

        public ExpandListAdapter(Context context, List<ExpandListGroup> groups) 
        {
            this.context = context;
            this.groups = groups;
        }

        public void AddItem(ExpandListChildAbs item, ExpandListGroup group) 
        {                              
            if (!groups.Contains(group)) 
            {
                groups.Add(group);
            }

            int index = groups.IndexOf(group);

            List<ExpandListChildAbs> ch = groups[index].Items;

            ch.Add(item);
            groups[index].Items = ch;
        }

        public override bool HasStableIds
        {
            get { return true; }
        }

        public override bool IsChildSelectable(int arg0, int arg1)
        {
            return true;
        }

        //______________________________________________________________________________________________________
        // Get Child Methods
        //______________________________________________________________________________________________________

        public override long GetChildId(int groupPosition, int childPosition)
        {
            return childPosition;                
        }

        public override int GetChildrenCount(int groupPosition)
        {
            List<ExpandListChildAbs> chList = groups[groupPosition].Items;               

            return chList.Count;
        }

        public override int ChildTypeCount
        {
            get { return Enum.GetNames(typeof(ChildTypes)).Length; }
        }

        public override int GetChildType(int groupPosition, int childPosition)
        {   
            //return base.GetChildType(groupPosition, childPosition);

            if (groupPosition == 0)
            {
                return (int)ChildTypes.ChildType1;
            }

            if (groupPosition == 1)
            {
                return (int)ChildTypes.ChildType2;
            }

            return 0;
        }

        public override Java.Lang.Object GetChild(int groupPosition, int childPosition)
        {
            List<ExpandListChildAbs> chList = groups[groupPosition].Items;

            return chList[childPosition];
        }

        public override View GetChildView(int groupPosition, int childPosition, bool isLastChild, View view, ViewGroup parent)
        {
            int ChildType = GetChildType(groupPosition, childPosition);

            if (ChildType == (int)ChildTypes.ChildType1)
            {
                return GetChildView_ChildType1(groupPosition, childPosition, isLastChild, view, parent);
            }

            if (ChildType == (int)ChildTypes.ChildType2)
            {
                return GetChildView_ChildType2(groupPosition, childPosition, isLastChild, view, parent);
            }

            return null;
        }

        private View GetChildView_ChildType1(int groupPosition, int childPosition, bool isLastChild, View view, ViewGroup parent)
        {   
            ExpandListChild1 child1 = (ExpandListChild1)GetChild(groupPosition, childPosition);

            if (view == null)
            {
                LayoutInflater infalInflater = (LayoutInflater)context.GetSystemService(Context.LayoutInflaterService);

                view = infalInflater.Inflate(Resource.Layout.ExpandList_ChildItem1, null);
            }

            TextView tv = view.FindViewById<TextView>(Resource.Id.tvChild1);

            tv.Text = child1.Name;
            tv.Tag = child1.Tag;

            return view;
        }

        private View GetChildView_ChildType2(int groupPosition, int childPosition, bool isLastChild, View view, ViewGroup parent)
        {
            ExpandListChild2 child2 = (ExpandListChild2)GetChild(groupPosition, childPosition);

            if (view == null)
            {
                LayoutInflater infalInflater = (LayoutInflater)context.GetSystemService(Context.LayoutInflaterService);

                view = infalInflater.Inflate(Resource.Layout.ExpandList_ChildItem2, null);
            }

            TextView tv = view.FindViewById<TextView>(Resource.Id.tvChild2);

            tv.Text = child2.Name;
            tv.Tag = child2.Tag;

            return view;
        }

        //________________________________________________________________________________________________________


        //______________________________________________________________________________________________________
        // Get Group Methods
        //______________________________________________________________________________________________________

        public override long GetGroupId(int groupPosition)
        {
            return groupPosition;
        }

        public override int GroupCount
        {
            get { return groups.Count; }
        }

        public override int GroupTypeCount 
        { 
            get { return base.GroupTypeCount; } 
        }

        public override int GetGroupType(int groupPosition)
        {
            return base.GetGroupType(groupPosition);
        }

        public override Java.Lang.Object GetGroup(int groupPosition)
        {
            return groups[groupPosition];
        }

        public override View GetGroupView(int groupPosition, bool isLastChild, View view, ViewGroup parent) 
        {
            ExpandListGroup group = (ExpandListGroup) GetGroup(groupPosition);

            if (view == null) 
            {
                LayoutInflater inf = (LayoutInflater) context.GetSystemService(Context.LayoutInflaterService);

                view = inf.Inflate(Resource.Layout.ExpandList_GroupItem, null);
            }

            TextView tv = view.FindViewById<TextView>(Resource.Id.tvGroup);

            tv.Text = group.Name;

            return view;
        }

        //________________________________________________________________________________________________________
    }      
}

---

MainLayout

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:id="@+id/ll_left_parcel"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  android:orientation="vertical"
  android:background="#FF8F8D8F">     

  <ExpandableListView
    android:id="@+id/elv_parcel_info"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:background="#FFCFCDCF"
    android:groupIndicator="@null"/>  

</LinearLayout>

---

ExpandList_GroupItem

<?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="55dip"
    android:background="#FF00AA55"
    android:orientation="vertical" >


  <TextView
      android:id="@+id/tvGroup"
      android:layout_width="fill_parent"
      android:layout_height="wrap_content"
      android:layout_marginRight="15dp"
      android:textColor="#FF000000"
      android:textSize="17dip" />

</LinearLayout>

---

ExpandList_ChildItem1

<?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="55dip"
    android:background="#FF8800CC"
    android:orientation="vertical" >

  <TextView
      android:id="@+id/tvChild1"
      android:layout_width="fill_parent"
      android:layout_height="wrap_content"
      android:textColor="#FF000000"
      android:textSize="17dip" />

</LinearLayout>

---

ExpandList_ChildItem2

<?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="55dip"
    android:background="#FFAA00FF"
    android:orientation="vertical" >

  <TextView
      android:id="@+id/tvChild2"
      android:layout_width="fill_parent"
      android:layout_height="wrap_content"
      android:textColor="#FF000000"
      android:textSize="17dip" />

</LinearLayout>

Answer 2

Android has a great collection of working code examples in the ApiDemos project. You can get it in eclipse as a New->"Android Sample Project". The ApiDemos has a nice example of an expandable list. It's a very good starting point before using a more complex and advanced example.