Android RuntimeException：アクティビティはOnFragmentInteractionListenerを実装する必要があります

Question

drawer layoutをfragmentsで実装しようとしています。 （フラグメントが表示されるべき）

content_main.xml：

<?xml version="1.0" encoding="utf-8"?> 
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
xmlns:app="http://schemas.android.com/apk/res-auto" 
xmlns:tools="http://schemas.android.com/tools" 
android:layout_width="match_parent" 
android:layout_height="match_parent" 
app:layout_behavior="@string/appbar_scrolling_view_behavior" 
tools:context="com.daveslab.wideview.MainActivity" 
tools:showIn="@layout/app_bar_main" 
android:id="@+id/FragmentPlaceLayout"> 
</RelativeLayout> 

MainActivity.java：

import android.os.Bundle; 
import android.support.design.widget.FloatingActionButton; 
import android.support.design.widget.Snackbar; 
import android.view.View; 
import android.support.design.widget.NavigationView; 
import android.support.v4.view.GravityCompat; 
import android.support.v4.widget.DrawerLayout; 
import android.support.v7.app.ActionBarDrawerToggle; 
import android.support.v7.app.AppCompatActivity; 
import android.support.v7.widget.Toolbar; 
import android.view.Menu; 
import android.view.MenuItem; 
import android.support.v4.app.FragmentManager; 
import layout.FragmentMain; 
...other stuff... 
public boolean onNavigationItemSelected(MenuItem item) { 
    // Handle navigation view item clicks here. 
    int id = item.getItemId(); 

    if (id == R.id.nav_camera) { 
     FragmentMain fragment_main = FragmentMain.newInstance("one","two"); 
     FragmentManager manager= getSupportFragmentManager(); 
     manager.beginTransaction().replace(R.id.FragmentPlaceLayout,fragment_main).commit(); 
    } else if (id == R.id.nav_gallery) { 

    } else if (id == R.id.nav_slideshow) { 

    } else if (id == R.id.nav_manage) { 

    } else if (id == R.id.nav_share) { 

    } else if (id == R.id.nav_send) { 

    } 

    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout); 
    drawer.closeDrawer(GravityCompat.START); 
    return true; 
} 

fragment_main.xml：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
xmlns:tools="http://schemas.android.com/tools" 
android:layout_width="match_parent" 
android:layout_height="match_parent" 
tools:context="layout.FragmentMain"> 

<TextView 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:text="@string/hello_blank_fragment" /> 

</RelativeLayout> 

FragmentMain.java：

09/25 11:16:55: Launching app 
.... 
Success 


$ adb shell am start -n  .... 

       [ 09-25 09:16:58.565 2534: 2534 D/   ] 
       HostConnection::get() New Host Connection established    0xad13bdf0, tid 2534 
I/OpenGLRenderer: Initialized EGL, version 1.4 
W/PathParser: Points are too far apart 4.000000596046461 
D/AndroidRuntime: Shutting down VM 


       --------- beginning of crash 
E/AndroidRuntime: FATAL EXCEPTION: main 
       Process: com.daveslab.wideview, PID: 2534 
java.lang.RuntimeException:com.daveslab.wideview.MainActivity@aa561a9 must  implement OnFragmentInteractionListener 
        at layout.FragmentMain.onAttach(FragmentMain.java:84) 
        at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1043) 
        at android.support.v4.app.BackStackRecord.setLastIn(BackStackRecord.java:838) 
        at android.support.v4.app.BackStackRecord.calculateFragments(BackStackRecord.java:878) 
        at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:719) 
        at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1677) 
        at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:536) 
        at android.os.Handler.handleCallback(Handler.java:739) 
        at android.os.Handler.dispatchMessage(Handler.java:95) 
        at android.os.Looper.loop(Looper.java:148) 
        at android.app.ActivityThread.main(ActivityThread.java:5417) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 
I/Process: Sending signal. PID: 2534 SIG: 9 
    Application terminated. 

いくつかのアイデア：

package layout; 

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; 

import com.daveslab.wideview.R; 

/** 
* A simple {@link Fragment} subclass. 
* Activities that contain this fragment must implement the 
* {@link FragmentMain.OnFragmentInteractionListener} interface 
* to handle interaction events. 
* Use the {@link FragmentMain#newInstance} factory method to 
* create an instance of this fragment. 
*/ 
public class FragmentMain extends Fragment { 
// 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 FragmentMain() { 
    // 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 FragmentMain. 
*/ 
// TODO: Rename and change types and number of parameters 
public static FragmentMain newInstance(String param1, String param2) { 
    FragmentMain fragment = new FragmentMain(); 
    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_main, 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; 
} 

/** 
* 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); 
} 
} 

私は引き出しのボタン コンソールログをクリックしたとき、私はエラーを取得しますか？

Answer 1

アクティビティにはOnFragmentInteractionListenerが含まれていないので、コードが見つからない場合は、この例外自体がelseケース内にスローされます。

if (context instanceof OnFragmentInteractionListener) { 
    mListener = (OnFragmentInteractionListener) context; 
} else { 
    throw new RuntimeException(context.toString() // Here is your exception 
      + " must implement OnFragmentInteractionListener"); 
} 

MainActivityでこれを行います。

Answer 2

MainActivityにOnFragmentInteractionListenerインターフェイスを実装しましたか？