How to get Spinner value?

The Spinner should fire an "OnItemSelected" event when something is selected:

spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
    public void onItemSelected(AdapterView<?> parent, View view, int pos, long id) {
        Object item = parent.getItemAtPosition(pos);
    }
    public void onNothingSelected(AdapterView<?> parent) {
    }
});

Yes, you can register a listener via setOnItemSelectedListener(), as is demonstrated here.

add setOnItemSelectedListener to spinner reference and get the data like that`

 mSizeSpinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> adapterView, View view, int position, long l) {
            selectedSize=adapterView.getItemAtPosition(position).toString();