What do @SuppressWarnings("deprecation") and ("unused") mean in Java?

The @SuppressWarnings annotation disables certain compiler warnings. In this case, the warning about deprecated code ("deprecation") and unused local variables or unused private methods ("unused"). This article explains the possible values.

One more thing: you can not only add them inline, but also annotate methods. For example

@Override
@SuppressWarnings("deprecation")
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    addPreferencesFromResource(R.xml.preferences);
}

Yet, it is recommended to use the smallest scope possible

As a matter of style, programmers should always use this annotation on the most deeply nested element where it is effective. If you want to suppress a warning in a particular method, you should annotate that method rather than its class.