In this tutorial, we’ll be implementing an application in which we display an ExpandableListView of items inside a NavigationView.
As we’d seen in the NavigationView tutorial, we can have submenus but those ones can’t be expanded/collapsed like we do in ExpandableListViews. So let’s try to implement the ExpandableListView inside a NavigationView.
Let’s start by creating a new Android Studio Project. Select the activity template as Navigation Drawer Activity as shown below.
This encloses our activity class in a DrawerLayout and adds a NavigationView inside it by default. In our xml editor we see the following design of the activity:
Now, all we need to do is replace the menus with an ExpandableListView.
In this application each of our menus while open a url in a WebView. Some menus can be expanded while others cannot. We’ll populate the data using the class MenuModel.
Let’s look at the layout file activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout xmlns:android="https://schemas.android.com/apk/res/android"
xmlns:app="https://schemas.android.com/apk/res-auto"
xmlns:tools="https://schemas.android.com/tools"
android:id="@+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:openDrawer="start">
<include
layout="@layout/app_bar_main"
android:layout_width="match_parent"
android:layout_height="match_parent" />
<android.support.design.widget.NavigationView
android:id="@+id/nav_view"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_gravity="start"
android:fitsSystemWindows="true"
app:headerLayout="@layout/nav_header_main">
<ExpandableListView
android:id="@+id/expandableListView"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="@dimen/nav_header_height"
android:background="@android:color/white"
android:dividerHeight="0dp"
android:groupIndicator="@null" />
</android.support.design.widget.NavigationView>
</android.support.v4.widget.DrawerLayout>
The code for the content_main.xml class is given below.
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="https://schemas.android.com/apk/res/android"
xmlns:app="https://schemas.android.com/apk/res-auto"
xmlns:tools="https://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
tools:context="com.journaldev.navigationviewexpandablelistview.MainActivity"
tools:showIn="@layout/app_bar_main">
<WebView
android:id="@+id/webView"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</android.support.constraint.ConstraintLayout>
The code for the layouts list_group_header.xml and list_group_child.xml which will be inflated in the Adapter class is given below.
list_group_header.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="https://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
android:id="@+id/lblListHeader"
android:layout_width="match_parent"
android:layout_height="?attr/listPreferredItemHeightSmall"
android:gravity="center_vertical"
android:paddingLeft="?android:attr/expandableListPreferredItemPaddingLeft"
android:paddingRight="?attr/listPreferredItemPaddingRight"
android:textColor="#1f2124"
android:textSize="16sp" />
</LinearLayout>
list_group_child.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="https://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:padding="8dp">
<TextView
android:id="@+id/lblListItem"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:paddingLeft="?android:attr/expandableListPreferredChildPaddingLeft" />
</LinearLayout>
The code for the MenuModel.java is given below.
package com.journaldev.navigationviewexpandablelistview;
public class MenuModel {
public String menuName, url;
public boolean hasChildren, isGroup;
public MenuModel(String menuName, boolean isGroup, boolean hasChildren, String url) {
this.menuName = menuName;
this.url = url;
this.isGroup = isGroup;
this.hasChildren = hasChildren;
}
}
The same class can be used for both the header and child rows of the ExpandableListView in this tutorial.
The code for the MainActivity.java class is given below.
package com.journaldev.navigationviewexpandablelistview;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.util.Log;
import android.view.View;
import android.support.design.widget.NavigationView;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
import android.webkit.WebView;
import android.widget.ExpandableListView;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
public class MainActivity extends AppCompatActivity
implements NavigationView.OnNavigationItemSelectedListener {
ExpandableListAdapter expandableListAdapter;
ExpandableListView expandableListView;
List<MenuModel> headerList = new ArrayList<>();
HashMap<MenuModel, List<MenuModel>> childList = new HashMap<>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
FloatingActionButton fab = findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
});
expandableListView = findViewById(R.id.expandableListView);
prepareMenuData();
populateExpandableList();
DrawerLayout drawer = findViewById(R.id.drawer_layout);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
drawer.addDrawerListener(toggle);
toggle.syncState();
NavigationView navigationView = findViewById(R.id.nav_view);
navigationView.setNavigationItemSelectedListener(this);
}
@Override
public void onBackPressed() {
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else {
super.onBackPressed();
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
@SuppressWarnings("StatementWithEmptyBody")
@Override
public boolean onNavigationItemSelected(MenuItem item) {
// Handle navigation view item clicks here.
int id = item.getItemId();
if (id == R.id.nav_camera) {
// Handle the camera action
} else if (id == R.id.nav_gallery) {
} else if (id == R.id.nav_slideshow) {
} else if (id == R.id.nav_manage) {
} else if (id == R.id.nav_share) {
} else if (id == R.id.nav_send) {
}
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
drawer.closeDrawer(GravityCompat.START);
return true;
}
private void prepareMenuData() {
MenuModel menuModel = new MenuModel("Android WebView Tutorial", true, false, "https://www.journaldev.com/9333/android-webview-example-tutorial"); //Menu of Android Tutorial. No sub menus
headerList.add(menuModel);
if (!menuModel.hasChildren) {
childList.put(menuModel, null);
}
menuModel = new MenuModel("Java Tutorials", true, true, ""); //Menu of Java Tutorials
headerList.add(menuModel);
List<MenuModel> childModelsList = new ArrayList<>();
MenuModel childModel = new MenuModel("Core Java Tutorial", false, false, "https://www.journaldev.com/7153/core-java-tutorial");
childModelsList.add(childModel);
childModel = new MenuModel("Java FileInputStream", false, false, "https://www.journaldev.com/19187/java-fileinputstream");
childModelsList.add(childModel);
childModel = new MenuModel("Java FileReader", false, false, "https://www.journaldev.com/19115/java-filereader");
childModelsList.add(childModel);
if (menuModel.hasChildren) {
Log.d("API123","here");
childList.put(menuModel, childModelsList);
}
childModelsList = new ArrayList<>();
menuModel = new MenuModel("Python Tutorials", true, true, ""); //Menu of Python Tutorials
headerList.add(menuModel);
childModel = new MenuModel("Python AST – Abstract Syntax Tree", false, false, "https://www.journaldev.com/19243/python-ast-abstract-syntax-tree");
childModelsList.add(childModel);
childModel = new MenuModel("Python Fractions", false, false, "https://www.journaldev.com/19226/python-fractions");
childModelsList.add(childModel);
if (menuModel.hasChildren) {
childList.put(menuModel, childModelsList);
}
}
private void populateExpandableList() {
expandableListAdapter = new ExpandableListAdapter(this, headerList, childList);
expandableListView.setAdapter(expandableListAdapter);
expandableListView.setOnGroupClickListener(new ExpandableListView.OnGroupClickListener() {
@Override
public boolean onGroupClick(ExpandableListView parent, View v, int groupPosition, long id) {
if (headerList.get(groupPosition).isGroup) {
if (!headerList.get(groupPosition).hasChildren) {
WebView webView = findViewById(R.id.webView);
webView.loadUrl(headerList.get(groupPosition).url);
onBackPressed();
}
}
return false;
}
});
expandableListView.setOnChildClickListener(new ExpandableListView.OnChildClickListener() {
@Override
public boolean onChildClick(ExpandableListView parent, View v, int groupPosition, int childPosition, long id) {
if (childList.get(headerList.get(groupPosition)) != null) {
MenuModel model = childList.get(headerList.get(groupPosition)).get(childPosition);
if (model.url.length() > 0) {
WebView webView = findViewById(R.id.webView);
webView.loadUrl(model.url);
onBackPressed();
}
}
return false;
}
});
}
}
prepareMenuData() is where we are populating our data structures with dummy datas.
For the group headers, we use an ArrayList of MenuModels.
The child rows data is populated in a HashMap where the key is the header MenuModel and the values are the list of child MenuModels.
In the onGroupClick and onChildClick Listeners of the ExpandableListView, we retrieve the url for the current position and load them in the WebView of our Activity.
Let’s look at the ExpandableListAdapter.java class.
package com.journaldev.navigationviewexpandablelistview;
import android.content.Context;
import android.graphics.Typeface;
import android.util.Log;
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;
public class ExpandableListAdapter extends BaseExpandableListAdapter {
private Context context;
private List<MenuModel> listDataHeader;
private HashMap<MenuModel, List<MenuModel>> listDataChild;
public ExpandableListAdapter(Context context, List<MenuModel> listDataHeader,
HashMap<MenuModel, List<MenuModel>> listChildData) {
this.context = context;
this.listDataHeader = listDataHeader;
this.listDataChild = listChildData;
}
@Override
public MenuModel getChild(int groupPosition, int childPosititon) {
return this.listDataChild.get(this.listDataHeader.get(groupPosition))
.get(childPosititon);
}
@Override
public long getChildId(int groupPosition, int childPosition) {
return childPosition;
}
@Override
public View getChildView(int groupPosition, final int childPosition,
boolean isLastChild, View convertView, ViewGroup parent) {
final String childText = getChild(groupPosition, childPosition).menuName;
if (convertView == null) {
LayoutInflater infalInflater = (LayoutInflater) this.context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
convertView = infalInflater.inflate(R.layout.list_group_child, null);
}
TextView txtListChild = convertView
.findViewById(R.id.lblListItem);
txtListChild.setText(childText);
return convertView;
}
@Override
public int getChildrenCount(int groupPosition) {
if (this.listDataChild.get(this.listDataHeader.get(groupPosition)) == null)
return 0;
else
return this.listDataChild.get(this.listDataHeader.get(groupPosition))
.size();
}
@Override
public MenuModel getGroup(int groupPosition) {
return this.listDataHeader.get(groupPosition);
}
@Override
public int getGroupCount() {
return this.listDataHeader.size();
}
@Override
public long getGroupId(int groupPosition) {
return groupPosition;
}
@Override
public View getGroupView(int groupPosition, boolean isExpanded,
View convertView, ViewGroup parent) {
String headerTitle = getGroup(groupPosition).menuName;
if (convertView == null) {
LayoutInflater infalInflater = (LayoutInflater) this.context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
convertView = infalInflater.inflate(R.layout.list_group_header, null);
}
TextView lblListHeader = convertView.findViewById(R.id.lblListHeader);
lblListHeader.setTypeface(null, Typeface.BOLD);
lblListHeader.setText(headerTitle);
return convertView;
}
@Override
public boolean hasStableIds() {
return false;
}
@Override
public boolean isChildSelectable(int groupPosition, int childPosition) {
return true;
}
}
Don’t forget to add the following permission in your AndroidManifest.xml file.
<uses-permission android:name="android.permission.INTERNET"/>
The output of the above application in action is given below.
This brings an end to this tutorial. You can download the final Android NavigationViewExpandableListView Tutorial from the link below.