How to create a multilevel ListView in an Android app?

AndroidApps/ApplicationsMobile Development

This example demonstrates how do I create a multilevel listView in android.

Step 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.

Step 2 − Add the following code to res/layout/activity_main.xml.

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:tools="http://schemas.android.com/tools"
   android:layout_width="match_parent"
   android:padding="4dp"
   android:layout_height="match_parent"
   tools:context=".MainActivity">
   <ExpandableListView
      android:id="@+id/expendableList"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:divider="@android:color/background_light"
      android:dividerHeight="0.5dp"/>
</RelativeLayout>

Step 3 − Add the following code to src/MainActivity.java

import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.ExpandableListAdapter;
import android.widget.ExpandableListView;
import android.widget.Toast;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
public class MainActivity extends AppCompatActivity {
   ExpandableListView expandableListView;
   ExpandableListAdapter expandableListAdapter;
   List<String>expandableListTitle;
   HashMap<String, List<String>> expandableListDetail;
   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      expandableListView = findViewById(R.id.expendableList);
      expandableListDetail = ExpandableListData.getData();
      expandableListTitle = new ArrayList<>(expandableListDetail.keySet());
      expandableListAdapter = new CustomExpandableListAdapter(this, expandableListTitle, expandableListDetail);
      expandableListView.setAdapter(expandableListAdapter);
      expandableListView.setOnGroupExpandListener(new ExpandableListView.OnGroupExpandListener() {
         @Override
         public void onGroupExpand(int groupPosition) {
         Toast.makeText(getApplicationContext(), expandableListTitle.get(groupPosition)
            + " List Expanded.", Toast.LENGTH_SHORT).show();
      }
   });
   expandableListView.setOnGroupCollapseListener(new ExpandableListView.OnGroupCollapseListener() {
      @Override
      public void onGroupCollapse(int groupPosition) {
         Toast.makeText(getApplicationContext(), expandableListTitle.get(groupPosition) + " List Collapsed.",
            Toast.LENGTH_SHORT).show();
      }
   });
   expandableListView.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;
         }
      });
   }
}

Step 4 − Create a java class (ExpandableListData.java) and the following code

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
class ExpandableListData {
   static HashMap<String, List<String>> getData() {
      HashMap<String, List<String>> expandableListDetail = new HashMap<>();
      List<String> myFavCricketPlayers = new ArrayList<>();
      myFavCricketPlayers.add("MS.Dhoni");
      myFavCricketPlayers.add("Sehwag");
      myFavCricketPlayers.add("Shane Watson");
      myFavCricketPlayers.add("Ricky Ponting");
      myFavCricketPlayers.add("Shahid Afridi");
      List<String> myFavFootballPlayers = new ArrayList<String>();
      myFavFootballPlayers.add("Cristiano Ronaldo");
      myFavFootballPlayers.add("Lionel Messi");
      myFavFootballPlayers.add("Gareth Bale");
      myFavFootballPlayers.add("Neymar JR");
      myFavFootballPlayers.add("David de Gea");
      List<String> myFavTennisPlayers = new ArrayList<String>();
      myFavTennisPlayers.add("Roger Federer");
      myFavTennisPlayers.add("Rafael Nadal");
      myFavTennisPlayers.add("Andy Murray");
      myFavTennisPlayers.add("Novak Jokovic");
      myFavTennisPlayers.add("Sania Mirza");
      expandableListDetail.put("CRICKET PLAYERS", myFavCricketPlayers);
      expandableListDetail.put("FOOTBALL PLAYERS", myFavFootballPlayers);
      expandableListDetail.put("TENNIS PLAYERS", myFavTennisPlayers);
      return expandableListDetail;
   }
}

Step 5 − Create a java class (CustomExpandableListAdapter.java) and the following code

package app.com.sample;
import android.content.Context;
import android.graphics.Typeface;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseExpandableListAdapter;
import android.widget.TextView;
import java.util.HashMap;
import java.util.List;
import java.util.Objects;
class CustomExpandableListAdapter extends BaseExpandableListAdapter {
   private Context context;
   private List<String> expandableListTitle;
   private HashMap<String, List<String>> expandableListDetail;
   CustomExpandableListAdapter(Context context, List<String> expandableListTitle, HashMap<String, List<String>> expandableListDetail) {
      this.context = context;
      this.expandableListTitle = expandableListTitle;
      this.expandableListDetail = expandableListDetail;
   }
   @Override
   public Object getChild(int listPosition, int expandedListPosition) {
      return
      Objects.requireNonNull(this.expandableListDetail.get(this.expandableListTitle.get(list Position))).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 = Objects.requireNonNull(layoutInflater).inflate(R.layout.list_row, null);
      }
      TextView textView = convertView.findViewById(R.id.listTitle);
      textView.setText(expandedListText);
      return convertView;
   }
   @Override
   public int getChildrenCount(int listPosition) {
      return
      this.expandableListDetail.get(this.expandableListTitle.get(listPosition)).size();
   }
   @Override
   public Object getGroup(int listPosition) {
      return this.expandableListTitle.get(listPosition);
   }
   @Override
   public int getGroupCount() {
      return this.expandableListTitle.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 = Objects.requireNonNull(layoutInflater).inflate(R.layout.list_row, null);
      }
      TextView listTitleTextView = convertView.findViewById(R.id.listTitle);
      listTitleTextView.setTypeface(null, Typeface.BOLD);
      listTitleTextView.setText(listTitle);
      return convertView;
   }
   @Override
   public boolean hasStableIds() {
      return false;
   }
   @Override
   public boolean isChildSelectable(int listPosition, int expandedListPosition) {
      return true;
   }
}

Step 6 − Create a layout resource file(list_row.xml) and add the following code −

<?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:padding="10dp"
      android:textColor="@android:color/black" />
</LinearLayout>

Step 7 − Add the following code to androidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="app.com.sample">
   <application
      android:allowBackup="true"
      android:icon="@mipmap/ic_launcher"
      android:label="@string/app_name"
      android:roundIcon="@mipmap/ic_launcher_round"
      android:supportsRtl="true"
      android:theme="@style/AppTheme">
         <activity android:name=".MainActivity">
            <intent-filter>
               <action android:name="android.intent.action.MAIN" />
               <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
      </activity>
   </application>
</manifest>

Let's try to run your application. I assume you have connected your actual Android Mobile device with your computer. To run the app from the android studio, open one of your project's activity files and click Run  icon from the toolbar. Select your mobile device as an option and then check your mobile device which will display your default screen −

Click here to download the project code.

raja
Published on 26-Nov-2019 07:27:52
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