在android中创建菜单时出错

问：

我正在尝试在android中创建一个菜单。但它只会导致只有文本的空白页。菜单未出现在屏幕上。代码如下

public class SimpleOptionMenu extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);


}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.menu, menu);
    return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
        case R.id.icon:     Toast.makeText(this, "You pressed the icon!", Toast.LENGTH_LONG).show();
                            break;
        case R.id.text:     Toast.makeText(this, "You pressed the text!", Toast.LENGTH_LONG).show();
                            break;
        case R.id.icontext: Toast.makeText(this, "You pressed the icon and text!", Toast.LENGTH_LONG).show();
                            break;
    }
    return true;

} }

请帮助解决这个问题。