No Job Of Star

안드로이드 백버튼 두번 누른 후 앱 종료동작

public class MainActivity extends Activity {
    private Context mContext = null;
    private long backKeyPressedTime = 0;


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

        mContext = this;
    }

@Override
public void onBackPressed() {
    if (System.currentTimeMillis() > backKeyPressedTime + 2000) {
        backKeyPressedTime = System.currentTimeMillis();
        Toast.makeText(this, "\'뒤로\'버튼을 한번 더 누르시면 종료됩니다.", Toast.LENGTH_SHORT).show();
        return;
    }
    if (System.currentTimeMillis() <= backKeyPressedTime + 2000) {
        super.onBackPressed();
    }
}