Android ExpandableListView: how to detect when the scroll hits the bottom/end of list

Question

I'm implementing an ExpandableListView on my app and I try to detect when the scroll hits the bottom of this ExpandableListView . I've tried using onScrollListener and onScrollChangedListener .

For the onScrollListener , it is called way too many times to be an acceptable solution.

However for the onScrollChangedListener , it seems to be what I want. The problem is that as ExpandableListView doesn't have 1 child level but 2, I don't manage to find a way to identify the last visible element.

Has anyone already implemented this kind of behaviour on an ExpandableListView ?

Answer 1

You can done via getting position of last group when it expand

expandableListView.setOnGroupClickListener(new ExpandableListView.OnGroupClickListener() {
        @Override
        public boolean onGroupClick(ExpandableListView parent, View v, int groupPosition, long id) {
            if(groupPosition == expandableListView.getExpandableListAdapter().getGroupCount()){
            // your code goes here
            }
            return false;
        }
    });

Answer 2

Try below sample:-

activity_main.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context=".MainActivity">

<ExpandableListView
    android:id="@+id/elvMain"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
</ExpandableListView>

</LinearLayout>

MainActivity.java:

public class MainActivity extends AppCompatActivity {
ArrayList<String> mainGroupList;
HashMap<String, ArrayList<String>> mainChildList;
CustomAdapter mainAdapter;
ExpandableListView elvMain;
int newDataSet = 0;

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

    elvMain = findViewById(R.id.elvMain);
    mainGroupList = new ArrayList<>();
    mainChildList = new HashMap<>();
    for(int i = 0; i < 20; i++){
        ArrayList<String> tmpList = new ArrayList<>();
        for(int j = 0; j< 17; j++){
            tmpList.add("Child " + j);
        }
        mainChildList.put("Group " + i, tmpList);
        mainGroupList.add("Group " + i);
    }
    mainAdapter = new CustomAdapter(this, mainGroupList, mainChildList);
    elvMain.setAdapter(mainAdapter);

    elvMain.setOnScrollListener(new AbsListView.OnScrollListener() {
        @Override
        public void onScrollStateChanged(AbsListView absListView, int i) {}
        @Override
        public void onScroll(AbsListView absListView, int i, int i1, int i2) {
            if(i2 == i + i1){
                View lastView = absListView.getChildAt(i1 - 1);
                if(lastView.getBottom() == absListView.getBottom()){
                    try{
                        String viewTag = lastView.getTag().toString();
                        if(viewTag.equals("Group")){
                            Toast.makeText(getApplicationContext(),
                                    "No more data, unless expanded the last group!!",
                                    Toast.LENGTH_SHORT).show();
                            //elvMain.expandGroup(mainAdapter.getGroupCount() - 1);
                        }
                    }catch(Exception e){
                        addNewData();
                    }
                }
            }
        }
    });
}

private void addNewData(){
    newDataSet++;
    for(int i = 0; i < 5; i++){
        ArrayList<String> tmpList = new ArrayList<>();
        for(int j = 0; j< 7; j++){
            tmpList.add("Child " + j);
        }
        mainChildList.put("Added " + newDataSet + ",Group " + i, tmpList);
        mainGroupList.add("Added " + newDataSet + ",Group " + i);
    }
    mainAdapter.notifyDataSetChanged();
}
}

CustomAdapter.java:

public class CustomAdapter extends BaseExpandableListAdapter {
ArrayList<String> groupList;
HashMap<String, ArrayList<String>> childList;
LayoutInflater inflater;

public CustomAdapter(Context context, ArrayList<String> groupList, HashMap<String, ArrayList<String>> childList) {
    this.inflater = LayoutInflater.from(context);
    this.groupList = groupList;
    this.childList = childList;
}

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

@Override
public int getChildrenCount(int i) {
    return childList.get(groupList.get(i)).size();
}

@Override
public String getGroup(int i) {
    return groupList.get(i);
}

@Override
public String getChild(int i, int i1) {
    return childList.get(groupList.get(i)).get(i1);
}

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

@Override
public long getChildId(int i, int i1) {
    return 0;
}

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

@Override
public View getGroupView(int i, boolean b, View view, ViewGroup viewGroup) {
    if(view == null) view = inflater.inflate(android.R.layout.simple_list_item_1, null);
    TextView textView = view.findViewById(android.R.id.text1);
    textView.setText(getGroup(i));
    view.setTag("Group");
    return view;
}

@Override
public View getChildView(int i, int i1, boolean b, View view, ViewGroup viewGroup) {
    if(view == null) view = inflater.inflate(android.R.layout.simple_list_item_1, null);
    TextView textView = view.findViewById(android.R.id.text1);
    textView.setText(getChild(i, i1));
    return view;
}

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

In this sample, I use setTag() to identify the view is "Group". If you use different layouts for group view and child view, then you may use findViewById() to find a view that is inside the group view and so no changes in your adapter.

In addition, inside the try-catch, you can comment out the Toast() and enable the code elvMain.expandGroup(mainAdapter.getGroupCount() - 1); which automatically expand the last group when the list is scrolled to the bottom, so the ExpandableListView becomes endless.

Hope that helps!

Answer 3

try this solution Detect when RecyclerView reaches the bottom most position while scrolling - check answer of Kaustubh Bhagwat

recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
    @Override
    public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
        super.onScrollStateChanged(recyclerView, newState);

        if (!recyclerView.canScrollVertically(1)) {
            Toast.makeText(YourActivity.this, "Last", Toast.LENGTH_LONG).show();

        }
    }
});