Create a spinner programmatically in Android

You need to add the Spinner to a layout.

First create a container for the Spinner and then create the Spinner and add it to your container. Next set content of you Activity to your container.

This could be done like this, in your onCreate method:

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_my);

    LinearLayout layout = new LinearLayout(this);

    ArrayList<String> spinnerArray = new ArrayList<String>();
    spinnerArray.add("one");
    spinnerArray.add("two");
    spinnerArray.add("three");
    spinnerArray.add("four");
    spinnerArray.add("five");

    Spinner spinner = new Spinner(this);
    ArrayAdapter<String> spinnerArrayAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_dropdown_item, spinnerArray);
    spinner.setAdapter(spinnerArrayAdapter);

    layout.addView(spinner);

    setContentView(layout);
}

EDIT:

Just to clarify: if the Spinner isn't added to the content of the Activity inside a layout, it isn't visible, so that's why you don't get any errors or anything, because there isn't any errors in your code, per se ;-)