Question

我在一个活动中使用了多个片段，并且在添加另一个片段之后，我添加了第一个，我得到的是自动生成的＆＃39;必须实现OnFragmentInteractionListener＆＃39;例外。该应用程序最初没有出现此错误，但在第二次运行后会抛出异常。据我所知，我已正确实施它们。任何帮助将不胜感激。

MainActivity：

package com.example.tom.navigationdrawertest;

import android.app.Activity;
import android.net.Uri;
import android.support.v4.app.FragmentTransaction;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.support.v4.widget.DrawerLayout;

import com.parse.Parse;


public class MainActivity extends ActionBarActivity
        implements NavigationDrawerFragment.NavigationDrawerCallbacks, ExploreFragment.OnFragmentInteractionListener, ActivityFragment.OnFragmentInteractionListener {

    /**
     * Fragment managing the behaviors, interactions and presentation of the navigation drawer.
     */
    private NavigationDrawerFragment mNavigationDrawerFragment;

    private ExploreFragment mExploreFragment;

    /**
     * Used to store the last screen title. For use in {@link #restoreActionBar()}.
     */
    private CharSequence mTitle;

    @Override
    public void onActivityFragmentInteraction(Uri uri){}

    @Override
    public void onExploreFragmentInteraction(Uri uri){}

// onCreate() etc etc

ActivityFragment：

//rest of the code

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        try {
            mListener = (OnFragmentInteractionListener) activity;
        } catch (ClassCastException e) {
            throw new ClassCastException(activity.toString()
                    + " must implement OnFragmentInteractionListener");
        }
    }

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

    /**
     * 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
        public void onActivityFragmentInteraction(Uri uri);
    }

}

ExploreFragment：

//rest of code
    public void onButtonPressed(Uri uri) {
        if (mListener != null) {
            mListener.onExploreFragmentInteraction(uri);
        }
    }

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        try {
            mListener = (OnFragmentInteractionListener) activity;
        } catch (ClassCastException e) {
            throw new ClassCastException(activity.toString()
                    + " must implement OnFragmentInteractionListener");
        }
    }

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

    /**
     * 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
        public void onExploreFragmentInteraction(Uri uri);
    }

Answer 1

您没有添加正确的片段。错误的含义是您的新Activity必须是OnFragmentInteractionListener的类型，您添加的第一个是正常的，但第二个不是。

onAttach方法必须返回OnFragmentInteractionListener Activity，例如MainActivity。

错误 - 必须实现OnFragmentInteractionListener - 但我想我有？

1 个答案: