Expandable ListView in Android tutorials

Hello friends,
today we are going to learn about Expandable list view in android. so when we want to create a list and child of a list at that time Expandable listview is used. so without wasting a time take a look of Expandable list view android application and that code.

first, we are going to write or create example files.

child_list_item.xml

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

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="wrap_content">
    <TextView
        android:id="@+id/expandedListItem"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:paddingLeft="?android:attr/expandableListPreferredChildPaddingLeft"
        android:paddingTop="10dp"
        android:paddingBottom="10dp" />
</LinearLayout>

groupof_item.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">
    <TextView
        android:id="@+id/listTitle"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:paddingLeft="?android:attr/expandableListPreferredItemPaddingLeft"
        android:textColor="@android:color/black"
        android:paddingTop="10dp"
        android:paddingBottom="10dp" />
</LinearLayout>

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/relativeLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_marginTop="50dp"
    tools:context=".MainActivity">

    <ExpandableListView
        android:id="@+id/expandableListView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:divider="@android:color/darker_gray"
        android:dividerHeight="0.5dp"
        android:indicatorLeft="?android:attr/expandableListPreferredItemIndicatorLeft" />

</RelativeLayout>

Now we need to create three java files. one for adapter second for data and the third one for create or set data in a list.

ExpandableListData.java

public class ExpandableListData {
    public static HashMap<String, List<String>> getData() {
        HashMap<String, List<String>> expan_list_data = new HashMap<String, List<String>>();

        List<String> food = new ArrayList<>();
        food.add("pizza");
        food.add("pani puri");
        food.add("chips");
        food.add("dabeli");
        food.add("sandwitch");

        List<String> colors = new ArrayList<String>();
        colors.add("red");
        colors.add("yellow");
        colors.add("blue");
        colors.add("green");
        colors.add("white");
        colors.add("black");
        colors.add("gray");


        expan_list_data.put("Food", food);
        expan_list_data.put("Colors", colors);
        return expan_list_data;
    }
}

ExpandableListAdapter.java

public class ExpandableListAdapter extends BaseExpandableListAdapter {

    private Context context;
    private List<String> expnlist;
    private HashMap<String, List<String>> exapnlisthasmap;

    public ExpandableListAdapter(Context context, List<String> expandableListTitle,
                                 HashMap<String, List<String>> expandableListDetail) {
        this.context = context;
        this.expnlist = expandableListTitle;
        this.exapnlisthasmap = expandableListDetail;
    }

    @Override
    public Object getChild(int listPosition, int expandedListPosition) {
        return this.exapnlisthasmap.get(this.expnlist.get(listPosition))
                .get(expandedListPosition);
    }

    @Override
    public long getChildId(int listPosition, int expandedListPosition) {
        return expandedListPosition;
    }

    @Override
    public View getChildView(int listPosition, final int expandedListPosition,
                             boolean isLastChild, View convertView, ViewGroup parent) {
        final String expandedListText = (String) getChild(listPosition, expandedListPosition);
        if (convertView == null) {
            LayoutInflater layoutInflater = (LayoutInflater) this.context
                    .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            convertView = layoutInflater.inflate(R.layout.child_list_item, null);
        }
        TextView expandedListTextView = (TextView) convertView
                .findViewById(R.id.expandedListItem);
        expandedListTextView.setText(expandedListText);
        return convertView;
    }
    @Override
    public int getChildrenCount(int listPosition) {
        return this.exapnlisthasmap.get(this.expnlist.get(listPosition))
                .size();
    }
    @Override
    public Object getGroup(int listPosition) {
        return this.expnlist.get(listPosition);
    }
    @Override
    public int getGroupCount() {
        return this.expnlist.size();
    }
    @Override
    public long getGroupId(int listPosition) {
        return listPosition;
    }
    @Override
    public View getGroupView(int listPosition, boolean isExpanded,
                             View convertView, ViewGroup parent) {
        String listTitle = (String) getGroup(listPosition);
        if (convertView == null) {
            LayoutInflater layoutInflater = (LayoutInflater) this.context.
                    getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            convertView = layoutInflater.inflate(R.layout.groupof_item, null);
        }
        TextView listtitle = (TextView) convertView
                .findViewById(R.id.listTitle);
        listtitle.setTypeface(null, Typeface.BOLD);
        listtitle.setText(listTitle);
        return convertView;
    }
    @Override
    public boolean hasStableIds() {
        return false;
    }
    @Override
    public boolean isChildSelectable(int listPosition, int expandedListPosition) {
        return true;
    }

   
MainActivity.java


public class MainActivity extends AppCompatActivity {
    ExpandableListView explistview;
    ExpandableListAdapter expandableListAdapter;
    List<String> expandableListTitle;
    HashMap<String, List<String>> expandableListDetail;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        explistview = (ExpandableListView) findViewById(R.id.expandableListView);
        expandableListDetail = ExpandableListData.getData();
        expandableListTitle = new ArrayList(expandableListDetail.keySet());
        expandableListAdapter = new ExpandableListAdapter(this, expandableListTitle, expandableListDetail);
        explistview.setAdapter(expandableListAdapter);
        explistview.setOnGroupExpandListener(new ExpandableListView.OnGroupExpandListener() {

            @Override
            public void onGroupExpand(int groupPosition) {
                Toast.makeText(getApplicationContext(), expandableListTitle.get(groupPosition) + " Open.", Toast.LENGTH_SHORT).show();
            }
        });

        explistview.setOnGroupCollapseListener(new ExpandableListView.OnGroupCollapseListener() {

            @Override
            public void onGroupCollapse(int groupPosition) {
                Toast.makeText(getApplicationContext(), expandableListTitle.get(groupPosition) + "Close.", Toast.LENGTH_SHORT).show();

            }
        });

        explistview.setOnChildClickListener(new ExpandableListView.OnChildClickListener() {
            @Override
            public boolean onChildClick(ExpandableListView parent, View v,
                                        int groupPosition, int childPosition, long id) {
                Toast.makeText(
                        getApplicationContext(),
                        expandableListTitle.get(groupPosition) + " -> " + expandableListDetail.get(expandableListTitle.get(groupPosition)).get(childPosition), Toast.LENGTH_SHORT
                ).show();
                return false;
            }
        });
    }

}