If you don't want to implement the listener, you can set it up like this directly where you want it (call on your spinner after your adapter has been set):
spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
switch (position) {
case 0:
Toast.makeText(parent.getContext(), "Spinner item 1!", Toast.LENGTH_SHORT).show();
break;
case 1:
Toast.makeText(parent.getContext(), "Spinner item 2!", Toast.LENGTH_SHORT).show();
break;
case 2:
Toast.makeText(parent.getContext(), "Spinner item 3!", Toast.LENGTH_SHORT).show();
break;
}
}
@Override
public void onNothingSelected(AdapterView<?> parent) {
// sometimes you need nothing here
}
});