ヌルポインタの例外 - Androidのフラグメントのボタン

Question

現在、私はAndroidのFragmentとActivityの間の通信に取り組んでいます。私がここで達成したいのは、フラグメントのボタンのonClickListenerです。しかし、NPEが発生し、なぜ私は見つけることができません。スタックフローには多くの類似の質問がありますが、私にとってはうまくいくものは見つかりませんでした。以下は私のコードとlogcatです。ここにたどり着いて、誰かが私を助けてくれることを願っています！

Logcat：

> 04-14 17:53:02.163 15136-15136/? E/AndroidRuntime: java.lang.RuntimeException: Unable to start activity 
> ComponentInfo{com.example.ivylin.corewar/com.example.ivylin.corewar.assistantWidgets.WarriorBattleSelfScreen}: 
> android.view.InflateException: Binary XML file line #7: Error 
> inflating class fragment 
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2298) 
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360) 
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.app.ActivityThread.access$800(ActivityThread.java:144) 
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278) 
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.os.Handler.dispatchMessage(Handler.java:102) 
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.os.Looper.loop(Looper.java:135) 
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.app.ActivityThread.main(ActivityThread.java:5221) 
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at java.lang.reflect.Method.invoke(Native Method) 
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at java.lang.reflect.Method.invoke(Method.java:372) 
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899) 
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694) 
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime: Caused by: android.view.InflateException: Binary XML file line #7: Error 
> inflating class fragment 
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:763) 
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.view.LayoutInflater.rInflate(LayoutInflater.java:806) 
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.view.LayoutInflater.inflate(LayoutInflater.java:504) 
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.view.LayoutInflater.inflate(LayoutInflater.java:414) 
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.view.LayoutInflater.inflate(LayoutInflater.java:365) 
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.support.v7.app.AppCompatDelegateImplV7.setContentView(AppCompatDelegateImplV7.java:256) 
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:109) 
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at com.example.ivylin.corewar.assistantWidgets.WarriorBattleSelfScreen.onCreate(WarriorBattleSelfScreen.java:36) 
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.app.Activity.performCreate(Activity.java:5933) 
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105) 
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251) 
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)  
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.app.ActivityThread.access$800(ActivityThread.java:144)  
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)  
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.os.Handler.dispatchMessage(Handler.java:102)  
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.os.Looper.loop(Looper.java:135)  
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.app.ActivityThread.main(ActivityThread.java:5221)  
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at java.lang.reflect.Method.invoke(Native Method)  
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at java.lang.reflect.Method.invoke(Method.java:372)  
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)  
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)  
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime: Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void 
> android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' 
> on a null object reference 
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at com.example.ivylin.corewar.assistantWidgets.WarriorBattleFragment.onCreateView(WarriorBattleFragment.java:46) 
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.app.Fragment.performCreateView(Fragment.java:2053) 
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:870) 
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1045) 
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.app.FragmentManagerImpl.addFragment(FragmentManager.java:1147) 
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.app.FragmentManagerImpl.onCreateView(FragmentManager.java:2116) 
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.app.Activity.onCreateView(Activity.java:5282) 
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.support.v4.app.BaseFragmentActivityHoneycomb.onCreateView(BaseFragmentActivityHoneycomb.java:34) 
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.support.v4.app.FragmentActivity.onCreateView(FragmentActivity.java:79) 
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:733) 
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.view.LayoutInflater.rInflate(LayoutInflater.java:806)  
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.view.LayoutInflater.inflate(LayoutInflater.java:504)  
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.view.LayoutInflater.inflate(LayoutInflater.java:414)  
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.view.LayoutInflater.inflate(LayoutInflater.java:365)  
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.support.v7.app.AppCompatDelegateImplV7.setContentView(AppCompatDelegateImplV7.java:256)  
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:109)  
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at com.example.ivylin.corewar.assistantWidgets.WarriorBattleSelfScreen.onCreate(WarriorBattleSelfScreen.java:36)  
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.app.Activity.performCreate(Activity.java:5933)  
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)  
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251)  
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)  
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.app.ActivityThread.access$800(ActivityThread.java:144)  
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)  
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.os.Handler.dispatchMessage(Handler.java:102)  
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.os.Looper.loop(Looper.java:135)  
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at android.app.ActivityThread.main(ActivityThread.java:5221)  
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at java.lang.reflect.Method.invoke(Native Method)  
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at java.lang.reflect.Method.invoke(Method.java:372)  
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)  
>  04-14 17:53:02.163 15136-15136/? E/AndroidRuntime:  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694) 

logcatは、主にボタンBOKがnullであることを伝えているようです。以下の詳細コードをご覧ください。

マイ・フラグメント：

public class WarriorBattleFragment extends Fragment implements View.OnClickListener { 
private RecyclerView recyclerView; 
private WarriorBattleAdapter adapter; 

EditText nP1; 
EditText nP2; 
Button bStart; 
static private int click; 

@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
} 

@Override 
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstance) { 
    View layout = inflater.inflate(R.layout.activity_warrior_self_battle_recyclerview, container, false); 
    recyclerView = (RecyclerView) layout.findViewById(R.id.recycler_view); 
    LinearLayoutManager layoutManager; 

    bStart = (Button) recyclerView.findViewById(R.id.bOK); 
    nP1 = (EditText) recyclerView.findViewById(R.id.nP1); 
    nP2 = (EditText) recyclerView.findViewById(R.id.nP2); 
    bStart.setOnClickListener(this); 

    layoutManager = new LinearLayoutManager(getActivity(), LinearLayoutManager.HORIZONTAL, false); 
    recyclerView.setLayoutManager(layoutManager); 
    adapter = new WarriorBattleAdapter(getActivity()); 
    recyclerView.setAdapter(adapter); 
    return layout; 
} 


@Override 
public void onClick(View v) { 
    switch (v.getId()) { 
     case R.id.bStart: 
      if (UserInformation.selectedBW[0].equals("") && UserInformation.selectedBW[1].equals("")) { 
       Toast.makeText(getActivity().getApplicationContext(), "Please Choose A Warrior", Toast.LENGTH_SHORT).show(); 
      } else { 
       click++; 
       if (click == 1) { 
        nP1.setText(UserInformation.selectedBW[0]); 
        adapter.setAdded(1); 
       } else if (click == 2) { 
        bStart.setText("BATTLE!"); 
       } else if (click == 3) { 
        Toast.makeText(getActivity().getApplicationContext(), "WARRIOR FILES UPLOADING", Toast.LENGTH_SHORT).show(); 
       } 
      } 
      if (!UserInformation.selectedBW[0].equals("")) { 
       Intent intent = new Intent(getActivity().getApplicationContext(), DemoDisplay.class); 
       intent.putExtra("wName", UserInformation.selectedBW[0]); 
       intent.putExtra("MODE", UserInformation.selectedBW[0]); 
       startActivity(intent); 

      } else { 
       Toast.makeText(getActivity().getApplicationContext(), "Please select one warrior", Toast.LENGTH_SHORT).show(); 
      } 
      break; 
    } 

} 
} 

My活動：フラグメントで

public class WarriorBattleSelfScreen extends AppCompatActivity implements View.OnClickListener { 
Button bBack; 
Intent intent; 
static int click; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    // set to full screen 
    requestWindowFeature(Window.FEATURE_NO_TITLE); 
    getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN); 

    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_warrior_battle_self_screen); 
    bBack = (Button) findViewById(R.id.bBack); 

    // THIS PART IS FOR TEST 
    UserInformation.empty = false; 
    WarriorCardEntity imp = new WarriorCardEntity(); 
    imp.title = "Imp"; 
    imp.image = R.drawable.w9; 
    UserInformation.dataContainer.put(0, imp); 
    WarriorCardEntity rave = new WarriorCardEntity(); 
    rave.title = "Rave"; 
    rave.image = R.drawable.w10; 
    UserInformation.dataContainer.put(1, rave); 
    WarriorCardEntity lin = new WarriorCardEntity(); 
    lin.title = "lin"; 
    lin.image = R.drawable.w20; 
    UserInformation.dataContainer.put(2, lin); 

    bBack.setOnClickListener(this); 
} 

@Override 
public void onClick(View v) { 
    switch (v.getId()) { 
     case R.id.bBack: 
      finish(); 
      break; 
    } 
} 
} 

XML：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:screenOrientation="landscape" 
    android:background="@drawable/background_gene"> 

    <fragment class="com.example.ivylin.corewar.assistantWidgets.WarriorBattleFragment" 
     android:id="@+id/b_self_fragment" 
     android:layout_width="match_parent" 
     android:layout_height="320dp" 
     android:layout_centerVertical="true" 
     android:layout_toRightOf="@+id/Add" 
     android:layout_toEndOf="@+id/Add" 
     android:layout_marginLeft="30dp" /> 

    <Button 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:text="Back" 
     android:background="@drawable/button" 
     android:textColor="@color/white" 
     android:id="@+id/bBack" 
     android:layout_marginLeft="33dp" 
     android:layout_marginStart="33dp" 
     android:layout_marginBottom="20dp" 
     android:layout_alignParentBottom="true" 
     android:layout_alignParentLeft="true" 
     android:layout_alignParentStart="true" /> 

</RelativeLayout> 

activity_warrior_battle_self_screen Activity--で

activity_warrior_self_battle_recyclerview 

<?xml version="1.0" encoding="utf-8"?> 
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:fitsSystemWindows="true" 
    android:screenOrientation="landscape" 
    > 

    <RelativeLayout 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:layout_centerInParent="true"> 

     <android.support.v7.widget.RecyclerView 
      android:id="@+id/recycler_view" 
      android:layout_width="match_parent" 
      android:layout_height="match_parent" 
      android:layout_alignParentBottom="true"> 
     </android.support.v7.widget.RecyclerView> 


     <TextView 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:text="P1: " 
      android:textSize="20sp" 
      android:textColor="@color/white" 
      android:id="@+id/tP1" 
      /> 
     <EditText 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:id="@+id/nP1" 
      android:layout_toRightOf="@+id/tP1" 
      android:hint="WARRIOR1" 
      android:textColor="@color/white" 
      android:textColorHint="@color/white"/> 

     <TextView 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:text="P2: " 
      android:layout_marginLeft="400dp" 
      android:textSize="20sp" 
      android:textColor="@color/white" 
      android:id="@+id/tP2" 
      /> 
     <EditText 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:id="@+id/nP2" 
      android:layout_toRightOf="@+id/tP2" 
      android:layout_alignParentRight="true" 
      android:hint="WARRIOR2" 
      android:textColor="@color/white" 
      android:textColorHint="@color/white"/> 

     <Button 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:text="OK" 
      android:background="@drawable/button" 
      android:textColor="@color/white" 
      android:id="@+id/bOK" 
      android:layout_marginRight="33dp" 
      android:layout_marginEnd="33dp" 
      android:layout_marginBottom="0dp" 
      android:layout_alignParentBottom="true" 
      android:layout_alignParentRight="true" 
      android:layout_alignParentEnd="true" /> 


    </RelativeLayout> 
</RelativeLayout> 

XML

Answer 1

。

あなたが代わりにあなたのルートビューでそれを呼び出す必要があります：

@Override 
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstance) { 
    View layout = inflater.inflate(R.layout.activity_warrior_self_battle_recyclerview, container, false); 
    recyclerView = (RecyclerView) layout.findViewById(R.id.recycler_view); 
    LinearLayoutManager layoutManager; 


    //change to layout.findViewById(): 
    bStart = (Button) layout.findViewById(R.id.bOK); //modified 
    nP1 = (EditText) layout.findViewById(R.id.nP1); //modified 
    nP2 = (EditText) layout.findViewById(R.id.nP2); //modified 
    bStart.setOnClickListener(this); 

    layoutManager = new LinearLayoutManager(getActivity(), LinearLayoutManager.HORIZONTAL, false); 
    recyclerView.setLayoutManager(layoutManager); 
    adapter = new WarriorBattleAdapter(getActivity()); 
    recyclerView.setAdapter(adapter); 
    return layout; 
} 

Answer 2

はい、recyclerView.findViewById(R.id.bOK);への呼び出しはnullを返します。これは、ビューグループrecyclerViewにidが 'bOK'のボタンがなく、findViewById()というボタンを見つけようとしているためです。あなたのレイアウトで

開いていると瞬時にRecyclerViewタグを閉じる：

<android.support.v7.widget.RecyclerView 
    android:id="@+id/recycler_view" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:layout_alignParentBottom="true"> 
</android.support.v7.widget.RecyclerView> 

ちょうど偶然おそらくでした。あなたはこのように、あなたのボタンの後までではなかっタグを閉じる必要があります - ボタンをRecyclerViewにする必要がある場合：あなたはRecyclerViewにfindViewById()を呼んでいる

<Button 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:text="OK" 
      android:background="@drawable/button" 
      android:textColor="@color/white" 
      android:id="@+id/bOK" 
      android:layout_marginRight="33dp" 
      android:layout_marginEnd="33dp" 
      android:layout_marginBottom="0dp" 
      android:layout_alignParentBottom="true" 
      android:layout_alignParentRight="true" 
      android:layout_alignParentEnd="true" /> 

</android.support.v7.widget.RecyclerView> 

Answer 3

あなたが@Michaと@Daniel

しかし

での回答に従って、あなたのコードでログを改正をしなければなりません全く異なる問題を示しています -

あなたのactivity_warrior_self_battle_recyclerview.xml

に親RelativeLayoutためandroid:screenOrientation="landscape"属性と android:screenOrientationがRelativeLayoutの有効なアンドロイドの属性ではありませんので、それは間違っています。