How to store selected items of an ExpandableListView in an ArrayList

Question

I have a list of users inside of an ExpandableListView, for now I have 2 groups of list, now I'm trying to create an ArrayList that will add data as I click on the users, so if have 2 groups of schools and I click on a student of each one I should have 2 positions in my array, one for each group containing its respective users, my problem is, my array has 2 positions but it is not separating the students:

What I want is this:

School A:

student1 selected

student2

student3 selected

School B:

student4

student5 selected

Resulting in this:

[0]-> student 1,3 [1] ->student 5

Here is what I tried so far:

mGpsEscolas = new GPSEscolas();
mArrayEscolas = new ArrayList<GPSEscolas>();
aMap = new HashMap<String, GPSEscolas>();

ExpandList.setOnChildClickListener(new ExpandableListView.OnChildClickListener() {
    @Override
    public boolean onChildClick(final ExpandableListView parent, View v, final int groupPosition, final int childPosition, final long id) {
        ExpAdapter.setClicked(groupPosition, childPosition);

        index = parent.getFlatListPosition(ExpandableListView.getPackedPositionForChild(groupPosition, childPosition));
        parent.setItemChecked(index, true);
        parent.setSelectedChild(groupPosition, childPosition, true);
        parent.getChildAt(index);

        IdAlunos = String.valueOf(mMainRest.mArrayList.get(groupPosition).getalunos().get(childPosition).getId_aluno());
        IdEscola = String.valueOf(mMainRest.mArrayList.get(groupPosition).getId_escola());

        ids_alunos.add(IdAlunos);


        notificar.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {






int groupCount = ExpandList.getExpandableListAdapter().getGroupCount();

                        for (int group = 1; group <= groupCount; group++) {
                            int gcount = ExpandList.getExpandableListAdapter().getChildrenCount(groupPosition);
                            mArrayEscolas = new ArrayList<GPSEscolas>();

                            for (int child = 1; child <= gcount; child++) {

                                mGpsEscolas.setIds_alunos(String.valueOf(IdAlunos).substring(1));
                                mGpsEscolas.setId_escola(Integer.valueOf(IdEscola));
                                mGpsEscolas.setLatitude(latitudeEscola);
                                mGpsEscolas.setLongitude(longitudeEscola);
                                mGpsEscolas.setDistancia(mMainRest.RaioEscola);

                                mArrayEscolas.add(mGpsEscolas);

                                if (ExpAdapter.isChildSelectable(groupPosition, childPosition)) {
                                    aMap.put(ExpandList.getExpandableListAdapter().getChildId(group, child), mArrayEscolas);
                                }


                            }
                        }


                }
        });

        return false;
    }
});

Answer 1

An easy solution is to create a new class SelectableObject:

class SelectableObject<T>
{
    boolean sel; T obj;
    public SelectableObject<T>(T obj) { this.obj=obj; this.sel=false; }
    public void select() { this.sel=true; }
    public void deselect() { this.sel=false; }
    public boolean isSelected() { return this.sel; }
    public T getObject() { return this.obj; }
}

then create your ExpandableListView like this

public void setChildData() 
{
    ArrayList<SelectableObject<GPSEscolas>> child
         = new ArrayList<SelectableObject<GPSEscolas>>();

    child.add(new SelectableObject<GPSEscolas>(new GPSEscolas(..)));

    ..

    childItems.add(child);
}

Then we need to make the onSelect listener function call select function

mExpandableList.setOnChildClickListener(new OnChildClickListener() {
  @Override public boolean onChildClick(ExpandableListView parent,
    View v,int groupPosition, int childPosition, long id) {

        SelectableObject<GPSEscolas> item = (SelectableObject<GPSEscolas>)
              parent.getExpandableListAdapter().getChild(groupPosition,childPosition);

        if(!item.isSelected()) item.select();
        else item.deselect();

        ..

  })

Then we can query selected items like this

public static ArrayList<GPSEscolas> getSelectedChildren(ExpandableListView listView)
{
    ArrayList<GPSEscolas> list = new ArrayList<GPSEscolas>();

    int count = listView.getGroupCount();

    for (int group = 1; group <= count; group++)
    {
      int gcount = listView.getChildrenCount(position);

      for (int child = 1; child <= gcount; child++)
      {
          SelectableObject<GPSEscolas> item = (SelectableObject<GPSEscolas>)
            listView.getExpandableListAdapter().getChild(groupPosition,childPosition);

          // Here is where you can see the solution beauty

          if (item.isSelected())
          {
              list.add(item.getObject());
          }
      }
    }

    return list;
}