Return message if no checkbox is selected

Question

How to do the treatment in this code so that it returns message to the user select at least one checkbox if it does not select any?

    public void verificaCheckBox(){

    Listcheck.clear();

    if (cbPapel.isChecked())
        Listcheck.add(cbPapel.getText().toString());

    if (cbPlastico.isChecked())
        Listcheck.add(cbPlastico.getText().toString());

    if (cbMetal.isChecked())
        Listcheck.add(cbMetal.getText().toString());

    if (cbVidro.isChecked())
        Listcheck.add(cbVidro.getText().toString());


        cbSelecionado = (Listcheck.toString());

}

Answer 1

Another way would be to test the size of your list Listcheck(supposing that your list is a Collection) after passing through their if addition.

public void verificaCheckBox(){

  Listcheck.clear();

  if (cbPapel.isChecked())
    Listcheck.add(cbPapel.getText().toString());

  if (cbPlastico.isChecked())
    Listcheck.add(cbPlastico.getText().toString());

  if (cbMetal.isChecked())
    Listcheck.add(cbMetal.getText().toString());

  if (cbVidro.isChecked())
    Listcheck.add(cbVidro.getText().toString());

  if(Listcheck.size() > 0){
    cbSelecionado = (Listcheck.toString());
  }else{
    //nenhum checkbox selecionado
  }

}

Answer 2

if (cbPapel.isChecked())
   Listcheck.add(cbPapel.getText().toString());

if (cbPlastico.isChecked())
   Listcheck.add(cbPlastico.getText().toString());

if (cbMetal.isChecked())
   Listcheck.add(cbMetal.getText().toString());

if (cbVidro.isChecked())
   Listcheck.add(cbVidro.getText().toString());

if (Listcheck.isEmpty()){
   //Msg que não foi selecionado nenhum
}