How to stack AlertDialog buttons vertically?

You can't do that with an AlertDialog . You should create a custom Dialog, and implement that yourself. Something like this would do it

Dialog dialog = new Dialog(context);
dialog.setContentView(R.layout.dialog_layout);
dialog.setTitle(...);
dialog.setMessage(...);
dialog.show();

and your layout dialog_layout.xml should be something like

<LinearLayout android:layout_width="match_parent"
              android:layout_height="wrap_content"
              orientation="vertical">

    <Button android:layout_width="wrap_content" android:layout_height="wrap_content"/>
    <Button android:layout_width="wrap_content" android:layout_height="wrap_content"/>
    <Button android:layout_width="wrap_content" android:layout_height="wrap_content"/>
</LinearLayout>

What if you did the alert box as a list?

@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
    AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
    builder.setTitle(R.string.pick_color)
           .setItems(R.array.colors_array, new DialogInterface.OnClickListener() {
               public void onClick(DialogInterface dialog, int which) {
               // The 'which' argument contains the index position
               // of the selected item
           }
    });
    return builder.create();
}

Example taken from here (under adding a list): https://developer.android.com/guide/topics/ui/dialogs.html

Then just take those list options and turn them into what you want.