Retrieving data from check boxes isn't working : Android Studio?

I wanted to store checked children names to firebase database. But then, this logic isn't working. I have a constructor with these fields in my Model class.

if (fatherRadioButton.isChecked())
  checkincheckout = new CheckInCheckOut(familyName, fatherName, null, checkInTime, checkOutTime, child1, child2, child3);
else
  checkincheckout = new CheckInCheckOut(familyName, null, motherName, checkInTime, checkOutTime, child1, child2, child3);

For CheckBoxes, the code is:

public void onCheckboxClicked(View view) {
  // Is the view now checked?
  boolean checked = ((CheckBox) view).isChecked();
  // Check which checkbox was clicked
  switch (view.getId()) {
    case R.id.checkbox_child1:
      if (checked) {
        child1 = child1CheckBox.getText().toString();
        Log.d(TAG, "Child 1 : " + child1);
      }
      break;
    case R.id.checkbox_child2:
      if (checked) {
        child2 = child2CheckBox.getText().toString();
        Log.d(TAG, "Child 2 : " + child2);
      }
      break;
    case R.id.checkbox_child3:
      if (checked) {
        child3 = child3CheckBox.getText().toString();
        Log.d(TAG, "Child 3 : " + child3);
      }
      break;
  }
}

I'm able to display them on LogCat too. Here is the trace:

05-23 15:39:27.741 26639-26639/D/tag: Radio Button - Mother Name Checked Mary Beth
05-23 15:39:28.116 26639-26639/D/tag: Child 1 : Zoe Johnson
05-23 15:39:28.349 26639-26639/D/tag: Child 2 : Chloe Johnson
05-23 15:39:28.766 26639-26639/D/tag: CheckIn Button Cliked!