spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
@Override
public void onItemSelected(AdapterView> parent, View view, int position, long id) {
int pos = spinner.getSelectedItemPosition();
String mysourcestring= yourarraylistname[+pos];
String substr=mysourcestring.substring(0,3).toUpperCase();
}
@Override
public void onNothingSelected(AdapterView> parent) {
}
});
now the value you want to pass will be in substr.
sorry if any errors,
hope this helps