JakeWharton

/* Base fragment to ensure the parent activity implements a contract interface. */
public abstract class ContractFragment<T> extends Fragment {
    private T mContract;

    @Override
    public void onAttach(Activity activity) {
        try {
            mContract = (T)activity;
        } catch (ClassCastException e) {
            throw new IllegalStateException(activity.getClass().getSimpleName()

romannurik

<!--
  A button bar is a set of buttons at the bottom of an activity.
  An example is an AlertDialog with OK/Cancel buttons.

  Note that something similar can be accomplished using a
  split action bar and text-only action buttons, but this is an
  alternate presentation that's often preferred.
-->
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"