Android Working with Spinner

activity_main.xml

    <Spinner
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_toRightOf="@+id/textView"
        android:layout_toEndOf="@+id/textView"
        android:layout_marginLeft="30dp"
        android:layout_marginStart="30dp"
        android:id="@+id/spinnerCountries" />
    Spinner spinner;
    ArrayAdapter<String> spinnerAdapter;
    String[] countries;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        spinner= (Spinner) findViewById(R.id.spinnerCountries);

        countries=getResources().getStringArray(R.array.countries);

        spinnerAdapter=new ArrayAdapter(this,android.R.layout.simple_spinner_item,countries);
        spinnerAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);

        spinner.setAdapter(spinnerAdapter);

        spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
                Toast toast=Toast.makeText(getBaseContext(),parent.getSelectedItem().toString(),Toast.LENGTH_LONG);
                toast.show();
            }

            @Override
            public void onNothingSelected(AdapterView<?> parent) {

            }
        });
    }

References
https://github.com/mhdr/AndroidSamples/tree/master/011