null pointer exception in onCreate()

private static final String PREFERENCES = "PREFERENCES";
private static final String URL = "url";
private String lastUrl;
private EditText urlText;
private TextView textView;

/** Called when the activity is first created. */

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

    urlText = (EditText) findViewById(R.id.address);
    textView = (TextView) findViewById(R.id.pagetext);

    loadPreferences();
    urlText.setText(lastUrl);
}