Infinite level expandable listview in android. Visit full project : https://github.com/kevalpatel2106/android-samples/tree/master/InfiniteExpandableListView

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:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.infiniteexpandablelistview.MainActivity">

    <ExpandableListView
        android:id="@+id/ParentLevel"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:groupIndicator="@null" />

</RelativeLayout>

InfiniteListAdapter.java

package com.infiniteexpandablelistview;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseExpandableListAdapter;
import android.widget.TextView;

import java.util.ArrayList;

/**
 * Created by Keval on 16-Feb-17.
 *
 * @author {@link 'https://github.com/kevalpatel2106'}
 */

public class InfiniteListAdapter extends BaseExpandableListAdapter {

    private final Context mContext;
    private final ArrayList<Subjects> mSubjects;

    public InfiniteListAdapter(Context context, ArrayList<Subjects> subjects) {
        mContext = context;
        mSubjects = subjects;
    }

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

    @Override
    public int getChildrenCount(int groupItemPos) {
        return mSubjects.get(groupItemPos).getSubList() == null
                || mSubjects.get(groupItemPos).getSubList().size() == 0 ? 0 : 1;
    }

    @Override
    public Subjects getGroup(int groupItemPos) {
        return mSubjects.get(groupItemPos);
    }

    @Override
    public Subjects getChild(int groupItemPos, int childItemPos) {
        return mSubjects.get(groupItemPos).getSubList().get(childItemPos);
    }

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

    @Override
    public long getChildId(int groupItemPos, int childItemPos) {
        return childItemPos;
    }

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

    @Override
    public View getGroupView(int groupItemPos, boolean isExpanded, View convertView, ViewGroup viewGroup) {
        GroupViewHolder groupViewHolder;
        if (convertView == null) {
            convertView = LayoutInflater.from(mContext).inflate(R.layout.item_group, viewGroup, false);

            groupViewHolder = new GroupViewHolder();
            groupViewHolder.mTextView = (TextView) convertView.findViewById(R.id.row_subject_title);

            convertView.setTag(groupViewHolder);
        } else {
            groupViewHolder = (GroupViewHolder) convertView.getTag();
        }

        Subjects parentItem = getGroup(groupItemPos);
        if (parentItem != null) {
            groupViewHolder.mTextView.setText(parentItem.getTitle());
        }

        return convertView;
    }

    @Override
    public View getChildView(int groupPos, int childPos, boolean isExpanded, View convertView, ViewGroup viewGroup) {
        ChildViewHolder childViewHolder;
        if (convertView == null) {
            convertView = LayoutInflater.from(mContext).inflate(R.layout.item_child, viewGroup, false);

            childViewHolder = new ChildViewHolder();
            childViewHolder.mExpandableListView = (SecondLevelExpandableListView) convertView.findViewById(R.id.row_group_list);

            convertView.setTag(childViewHolder);
        } else {
            childViewHolder = (ChildViewHolder) convertView.getTag();
        }

        Subjects childItem = getChild(groupPos, childPos);
        if (childItem != null) {
            childViewHolder.mExpandableListView.setAdapter(new InfiniteListAdapter(mContext, getGroup(groupPos).getSubList()));
        }

        return convertView;
    }

    @Override
    public boolean isChildSelectable(int i, int i1) {
        return true;
    }

    private class GroupViewHolder {
        private TextView mTextView;
    }


    private class ChildViewHolder {
        private SecondLevelExpandableListView mExpandableListView;
    }
}

item_child.xml

<?xml version="1.0" encoding="utf-8"?>
<com.infiniteexpandablelistview.SecondLevelExpandableListView
    android:id="@+id/row_group_list"
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:paddingLeft="10dp"
    android:layout_height="wrap_content"/>

item_group.xml

<TextView
    android:id="@+id/row_subject_title"
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:padding="2dp"
    android:textSize="16sp"
    android:orientation="vertical"/>

MainActivity.java

package com.infiniteexpandablelistview;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.widget.ExpandableListView;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {
    ArrayList<Subjects> mExampleList = new ArrayList<>();

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

        mExampleList = generateList(1);

        ExpandableListView mainListView = (ExpandableListView) findViewById(R.id.ParentLevel);
        mainListView.setAdapter(new InfiniteListAdapter(this, mExampleList));
    }

    private ArrayList<Subjects> generateList(int level) {
        ArrayList<Subjects> subjectses = new ArrayList<>();
        for (int i = 0; i < 6; i++) {
            Subjects subjects = new Subjects();
            subjects.setTitle("Level " + level + " -(" + i + ")");
            subjects.setId(i);
            if (level < 5)
                subjects.addSubjects(generateList(level + 1));
            subjectses.add(subjects);
        }

        return subjectses;
    }
}

SecondLevelExpandableListView.java

package com.infiniteexpandablelistview;

import android.content.Context;
import android.os.Build;
import android.support.annotation.RequiresApi;
import android.util.AttributeSet;
import android.widget.ExpandableListView;

/**
 * Created by Keval on 16-Feb-17.
 *
 * @author {@link 'https://github.com/kevalpatel2106'}
 */

public class SecondLevelExpandableListView extends ExpandableListView {


    public SecondLevelExpandableListView(Context context) {
        super(context);
    }

    public SecondLevelExpandableListView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public SecondLevelExpandableListView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
    public SecondLevelExpandableListView(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);
    }

    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        //999999 is a size in pixels. ExpandableListView requires a maximum height in order to do measurement calculations.
        heightMeasureSpec = MeasureSpec.makeMeasureSpec(999999, MeasureSpec.AT_MOST);
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    }
}

Subjects.java

package com.infiniteexpandablelistview;

import java.util.ArrayList;

/**
 * Created by Keval on 16-Feb-17.
 *
 * @author {@link 'https://github.com/kevalpatel2106'}
 */

public class Subjects {

    private ArrayList<Subjects> subList = new ArrayList<>();//second level sublist

    public Subjects(int id, String title, int sort, boolean sub) {
        this.id = id;
        this.title = title;
        this.sort = sort;
        this.hasSub = sub;
    }

    public Subjects(int id, String title) {
        this.id = id;
        this.title = title;
    }

    private int id;

    public Subjects() {

    }

    public int getSort() {
        return sort;
    }

    public void setSort(int sort) {
        this.sort = sort;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public boolean isHasSub() {
        return hasSub;
    }

    public void setHasSub(boolean hasSub) {
        this.hasSub = hasSub;
    }

    private int sort;
    private String title;
    private boolean hasSub;

    //second level sublist
    public ArrayList<Subjects> getSubList() {
        return subList;
    }

    // add second level sublist
    public void addSubject(Subjects subject) {
        this.subList.add(subject);
    }


    // add second level sublist
    public void addSubjects(ArrayList<Subjects> subject) {
        this.subList = (subject);
    }
}

Visit full project : https://github.com/kevalpatel2106/android-samples/tree/master/InfiniteExpandableListView