Expandable ListView Example

This example will show you how can you work with an expandable list in the android application.

Steps:-
1) Create two layout XML file.(One for header(parent) and Second for item list(child)).
2) Create one new java file for an expandable adapter.


Main.xml 

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout>
    <ExpandableListView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/myexpandablelist">
    </ExpandableListView>

</RelativeLayout>

header.xml 

<LinearLayout>
    <TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="New Text"
    android:id="@+id/textView2" />
</LinearLayout>

child.xml

<LinearLayout>

    <TextView       
     android:layout_width="wrap_content"   
     android:layout_height="wrap_content"
     android:text="New Text"      
     android:id="@+id/textView" />

</LinearLayout>

Main.java

public class MainActivity extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

ExpandableListView expandableListView = (ExpandableListView) findViewById(R.id.myexpandablelist);


ArrayList<String> myArrayHeader=new ArrayList<>();
HashMap<String,ArrayList<String>> myHashChild=new HashMap<>();

//Add  data to ArrayList        
myArrayHeader.add("Superman Vs Batman");
myArrayHeader.add("The Wolverine");
//Add data to HashMap
myHashChild.put("Movies", myArrayHeader);
//Add  data to ArrayList
myArrayHeader=new ArrayList<>();
myArrayHeader.add("I'll Be Your Man");
myArrayHeader.add("I Can't Give Everything Away");
//Add data to HashMap        
myHashChild.put("Music", myArrayHeader);
//Add  data to ArrayList
myArrayHeader=new ArrayList<>();
myArrayHeader.add("Breaking Bad");
myArrayHeader.add("Add to WatchlistGame of Thrones");
//Add data to HashMap        
myHashChild.put("Serials", myArrayHeader);

ArrayList<String> myArrayTitle=new ArrayList<>();
        myArrayTitle.add("Movies");
        myArrayTitle.add("Music");
        myArrayTitle.add("Serials");
 expandableListView.setAdapter(new MyRecylerAdapter(this, myHashChild, myArrayTitle));
}}

Myadapter.java

BaseExpandableListAdapter {

HashMap<String,ArrayList<String>> myHashChild;
Context context;
ArrayList<String> myArrayTitle;

public MyRecylerAdapter(MainActivity mainActivity, HashMap<String, ArrayList<String>>      myHashChild, ArrayList<String> myArrayTitle) {
        this.myHashChild=myHashChild;
        this.myArrayTitle=myArrayTitle;
        context=mainActivity;
    }

 @Override    
 public int getGroupCount() { return myHashChild.size();}

 @Override    
 public int getChildrenCount(int groupPosition) {
        return myHashChild.get(myArrayTitle.get(groupPosition)).size();
 }

@Override    
 public Object getGroup(int groupPosition) {return myHashChild.get(groupPosition);}

@Override    
public Object getChild(int groupPosition, int childPosition) {
  return myHashChild.get(groupPosition).get(childPosition);
}

@Override   
public long getGroupId(int groupPosition) { return 0;}

@Override    
public long getChildId(int groupPosition, int childPosition) { return 0; }

@Override    
public boolean hasStableIds() { return false;}

@Override     
public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {

LayoutInflater infalInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);

convertView = infalInflater.inflate(R.layout.header, null);
TextView myText=(TextView) convertView.findViewById(R.id.textView2);
myText.setText(myArrayTitle.get(groupPosition));
return convertView;
}

@Override    
public View getChildView(int groupPosition, int childPosition, boolean isLastChild, View convertView, ViewGroup parent) {

LayoutInflater infalInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        convertView = infalInflater.inflate(R.layout.child, null);
        TextView myText=(TextView) convertView.findViewById(R.id.textView);
        myText.setText(myHashChild.get(myArrayTitle.get(groupPosition)).get(childPosition));
        return convertView;
}

@Override    
public boolean isChildSelectable(int groupPosition, int childPosition) {
        return false;
}
}

Output