我想将回调代码更改为activity

public interface Callback {
    void onCallback(String result);
}

public class MainActivity extends AppCompatActivity {
    private Callback callback;

    public void setCallback(Callback callback) {
        this.callback = callback;
    }

    public void doSomething() {
        // 原本的回调函数逻辑
        // ...
        // 改为调用CallbackActivity的方法
        if (callback != null) {
            callback.onCallback("回调结果");
        }
    }
}

public class CallbackActivity extends Activity implements MainActivity.Callback {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_callback);

        MainActivity mainActivity = new MainActivity();
        mainActivity.setCallback(this);
        mainActivity.doSomething();
    }

    @Override
    public void onCallback(String result) {
        // 处理回调结果
        // ...
    }
}