expandableListView.java

  @Override
  protected void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    
   
    //////////////////////
    
    
    ExpandableListAdapter expandableListAdapter = new ExpandableListAdapter(this, dgResults);
    binding.expandableList.setAdapter(expandableListAdapter);
    
    binding.expandableList.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
        @Override
        public void onGlobalLayout() {
          setExpandableListViewHeight(binding.expandableList, -1);
          binding.expandableList.getViewTreeObserver().removeOnGlobalLayoutListener(this);
        }
      });

      binding.expandableList.setOnGroupClickListener((parent, v, position, id) -> {
        setExpandableListViewHeight(parent, position);
        return false;
      });
    }
}

private void setExpandableListViewHeight(ExpandableListView listView, int group) {
    ExpandableListAdapter listAdapter = listView.getExpandableListAdapter();
    int totalHeight = 0;
    int desiredWidth = View.MeasureSpec.makeMeasureSpec(listView.getWidth(), View.MeasureSpec.EXACTLY);

    for (int i = 0; i < listAdapter.getGroupCount(); i++) {
      View groupItem = listAdapter.getGroupView(i, false, null, listView);

      groupItem.measure(desiredWidth, View.MeasureSpec.UNSPECIFIED);
      totalHeight += groupItem.getMeasuredHeight();

      if (((listView.isGroupExpanded(i)) && (i != group)) || ((!listView.isGroupExpanded(i)) && (i == group))) {
        for (int j = 0; j < listAdapter.getChildrenCount(i); j++) {
          View listItem = listAdapter.getChildView(i, j, false, null, listView);

          listItem.measure(desiredWidth, View.MeasureSpec.UNSPECIFIED);
          totalHeight += listItem.getMeasuredHeight();
        }
      }
    }

    ViewGroup.LayoutParams params = listView.getLayoutParams();
    int height = totalHeight + (listView.getDividerHeight() * (listAdapter.getGroupCount() - 1));

    if (height < 10) height = 200;

    params.height = height;
    listView.setLayoutParams(params);
    listView.requestLayout();
  }