根据 parent activity 在片段中调用不同的方法

Question

我在我的应用程序中有一个包含一些输入字段的片段，我在两个不同的活动中显示这个片段，在这两种情况下，布局将相同但我需要根据谁是执行不同的操作parent activity.

我会尝试用以下代码更好地解释我的问题和我正在使用的解决方案：

ActivityA

public class ActivityA extends AppCompatActivity{
    private NavController navController;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.ActivityA);
        navController = Navigation.findNavController(this,R.id.graphA);
        initView();
    }
    public void nextFragment(int actionID, Bundle bundle) {
        btn.setOnClickListener(v->{
            navController.navigate(from_activityA_toFragment, bundle);
        });
    }

ActivityB

public class ActivityB extends AppCompatActivity{
    private NavController navController;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.ActivityA);
        navController = Navigation.findNavController(this,R.id.graphB);
        initView();
    }
    public void nextFragment(int actionID, Bundle bundle) {
        btn.setOnClickListener(v->{
            navController.navigate(from_activityB_toFragment, bundle);
        });
    }

在我的片段中 class 现在我有这样的东西

   @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View rootview = inflater.inflate(R.layout.fragemnt, container, false);
        if(getActivity().getClass().equals(ActivityA.class))
            //Do things of activityA
        else if(getActivity().getClass().equals(ActivityB.class)))
            //Do things of activityB
        return rootview;
    }

现在这段代码可以工作，但似乎不是实现我的目标的最佳方式，所以有人有什么建议吗？谢谢

Answer 1

您可以查看实例

在Java中你可以使用instaceof

if(getActivity() instanceof ActivityA){
  // Do things of activityA
}else if(getActivity() instanceof ActivityB){
  // Do things of activityB
}

对于 Kotlin

if(getActivity() is ActivityA){
  // Do things of activityA
}else if(getActivity() is ActivityB){
  // Do things of activityB
}

Answer 2

正确的做法是在Fragment中定义一个接口，让Activity实现接口，让Fragment将Activity强制转换为接口。

以下指南对其进行了描述：https://web.archive.org/web/20180405192526/https://developer.android.com/training/basics/fragments/communicating.html

public class HeadlinesFragment extends Fragment {
    OnHeadlineSelectedListener mCallback;

    // Container Activity must implement this interface
    public interface OnHeadlineSelectedListener {
        public void onArticleSelected(int position);
    }

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);

        // This makes sure that the container activity has implemented
        // the callback interface. If not, it throws an exception
        try {
            mCallback = (OnHeadlineSelectedListener) activity;
        } catch (ClassCastException e) {
            throw new ClassCastException(activity.toString()
                    + " must implement OnHeadlineSelectedListener");
        }
    }

    ...
}

根据 parent activity 在片段中调用不同的方法

Call different method in fragment based on parent activity

android

android-fragments

android-jetpack