涉及循环继承 [英] cyclic inheritance involving

问题描述

我正在尝试使用片段实现导航抽屉.我已经实现了导航抽屉，并且工作正常，但是当我单击片段时，出现错误消息:java.lang.RuntimeException:com.example.saarikakumar.factsappfull.MainActivity@1758ab2必须实现OnFragmentInteractionListener.

I am trying to implement a navigation drawer using fragments. I have the navigation drawer implemented and working well, but when I click on the fragments I get an error saying: java.lang.RuntimeException: com.example.saarikakumar.factsappfull.MainActivity@1758ab2 must implement OnFragmentInteractionListener.

当我尝试在片段中实现此方法和所需的方法时，它告诉我涉及该片段的循环继承.我在下面发布了我的片段代码:

When I try to implement this and the required methods in my fragment, it tells me that there is a cyclic inheritance involving the fragment. I am posting my fragment code below:

import android.content.Context;
import android.net.Uri;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

/**
 * A simple {@link Fragment} subclass.
 * Activities that contain this fragment must implement the
 * {@link FirstFragment.OnFragmentInteractionListener} interface
 * to handle interaction events.
 * Use the {@link FirstFragment#newInstance} factory method to
 * create an instance of this fragment.
 */


public class FirstFragment extends Fragment implements FirstFragment.OnFragmentInteractionListener {
    // TODO: Rename parameter arguments, choose names that match
    // the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
    private static final String ARG_PARAM1 = "param1";
    private static final String ARG_PARAM2 = "param2";

    // TODO: Rename and change types of parameters
    private String mParam1;
    private String mParam2;

    private OnFragmentInteractionListener mListener;

    public FirstFragment() {
        // Required empty public constructor
    }

    /**
     * Use this factory method to create a new instance of
     * this fragment using the provided parameters.
     *
     * @param param1 Parameter 1.
     * @param param2 Parameter 2.
     * @return A new instance of fragment SecondFragment.
     */
    // TODO: Rename and change types and number of parameters
    public static FirstFragment newInstance(String param1, String param2) {
        FirstFragment fragment = new FirstFragment();
        Bundle args = new Bundle();
        args.putString(ARG_PARAM1, param1);
        args.putString(ARG_PARAM2, param2);
        fragment.setArguments(args);
        return fragment;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if (getArguments() != null) {
            mParam1 = getArguments().getString(ARG_PARAM1);
            mParam2 = getArguments().getString(ARG_PARAM2);
        }
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_first, container, false);
    }

    // TODO: Rename method, update argument and hook method into UI event
    public void onButtonPressed(Uri uri) {
        if (mListener != null) {
            mListener.onFragmentInteraction(uri);
        }
    }

    @Override
    public void onAttach(Context context) {
        super.onAttach(context);
        if (context instanceof OnFragmentInteractionListener) {
            mListener = (OnFragmentInteractionListener) context;
        } else {
            throw new RuntimeException(context.toString()
                    + " must implement OnFragmentInteractionListener");
        }
    }

    @Override
    public void onDetach() {
        super.onDetach();
        mListener = null;
    }

    @Override
    public void onFragmentInteraction(Uri uri) {

    }


    /**
     * This interface must be implemented by activities that contain this
     * fragment to allow an interaction in this fragment to be communicated
     * to the activity and potentially other fragments contained in that
     * activity.
     * <p/>
     * See the Android Training lesson <a href=
     * "http://developer.android.com/training/basics/fragments/communicating.html"
     * >Communicating with Other Fragments</a> for more information.
     */
    public interface OnFragmentInteractionListener {
        // TODO: Update argument type and name
        void onFragmentInteraction(Uri uri);
    }
}

推荐答案

我知道这很旧，但是，您可以从错误中读取-> java.lang.RuntimeException:com.example.saarikakumar.factsappfull.MainActivity @ 1758ab2必须实现OnFragmentInteractionListener.

I know this is old but, as you can read from the error -> java.lang.RuntimeException: com.example.saarikakumar.factsappfull.MainActivity@1758ab2 must implement OnFragmentInteractionListener.

因此MainActivity是需要实现该接口的接口，因此该片段可以调用 mListener.notifyActivityOfSomething()之类的方法.

So MainActivity is the one that needs to implement the interface, so the fragment can call methods as mListener.notifyActivityOfSomething().

这篇关于涉及循环继承的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！