AlertDialog 형식의 Activity Dialog 만들기

public class DialogActivity extends Activity {
     
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
     
        final AlertDialog alertDialog = new AlertDialog.Builder(this).create();
        alertDialog.setTitle("알림");
        alertDialog.setMessage("Message");
alertDialog.setButton("확인", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
alertDialog.dismiss();
finish();
}
});
alertDialog.setButton2("취소", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
alertDialog.dismiss();
finish();
}
});      
        alertDialog.show();
     
        alertDialog.setOnKeyListener(new DialogInterface.OnKeyListener(){
@Override
public boolean onKey(DialogInterface dialog, int keyCode, KeyEvent event) {
if( keyCode == KeyEvent.KEYCODE_BACK ){
alertDialog.dismiss();
            finish();
}
return false;
}
        });      
    }
}