フラグメントのビューを初期化するとアプリケーションがクラッシュする

Question

JavaMailで使用するフラグメントの中にEditText、Button、およびOnClickListenerを作成しようとしていますが、このビューを削除するとアプリはうまく動作しますがJavaMailはそうしない。私は問題がフラグメントコードか他のどこかにあるかどうかわかりません。私はプログラミングに慣れていないので、どんな助けも歓迎です。

FragmentOne.Java

package info.androidhive.materialtabs.fragments; 

import android.os.Bundle; 
import android.support.v7.app.AppCompatActivity; 
import android.support.v4.app.Fragment; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.Button; 
import android.widget.EditText; 

import java.util.Properties; 

import javax.mail.PasswordAuthentication; 
import javax.mail.Session; 

import info.androidhive.materialtabs.R; 
import info.androidhive.materialtabs.SendMail; 

public class OneFragment extends Fragment implements View.OnClickListener { 

    //Declaring EditText 
    private EditText editTextMessage; 

    //Send button 
    private Button buttonSend; 

     public OneFragment() { 

     } // Required empty public constructor 

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


    private void sendEmail() { 
     //Getting content for email 
     String email = "myemail@gmail.com"; 
     String subject = "mySubject"; 
     String message = editTextMessage.getText().toString().trim(); 

     //Creating SendMail object 
     SendMail sm = new SendMail(this, email, subject, message); 

     //Executing sendmail to send email 
     sm.execute(); 
    } 

    @Override 
    public void onClick(View v) { 
     sendEmail(); 
    } 

    @Override 
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, 
          @Nullable Bundle savedInstanceState) { 
     View rootView = inflater.inflate(R.layout.fragment_one, container, false); 
     editTextMessage = (EditText) getView().findViewById(R.id.editTextMessage); 
     buttonSend = (Button) getView().findViewById(R.id.buttonSend); 

     //Adding click listener 
     buttonSend.setOnClickListener(this); 

     return rootView; 
    } 
} 

fragment_one.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="info.androidhive.materialtabs.fragments.OneFragment"> 

    <ScrollView 
     android:layout_width="match_parent" 
     android:layout_height="wrap_content" 
     android:layout_centerHorizontal="true" 
     tools:ignore="UselessParent"> 

     <LinearLayout 
      android:layout_width="match_parent" 
      android:layout_height="wrap_content" 
      android:orientation="vertical"> 

      <TextView 
       android:id="@+id/textView1" 
       android:layout_width="match_parent" 
       android:layout_height="wrap_content" 
       android:layout_marginTop="20dp" 
       android:gravity="center_vertical|center_horizontal|center" 
       android:text="@string/chamado" 
       android:textAppearance="@style/TextAppearance.AppCompat.Display1" 
       android:textColor="@color/colorPrimary" 
       android:textSize="30sp" 
       android:textStyle="normal" /> 

      <TextView 
       android:id="@+id/textView2" 
       android:layout_width="match_parent" 
       android:layout_height="wrap_content" 
       android:layout_marginTop="10dp" 
       android:gravity="center" 
       android:text="@string/preencha" /> 

      <EditText 
       android:id="@+id/editTextMessage" 
       android:layout_width="300dp" 
       android:layout_height="80dp" 
       android:layout_gravity="center_horizontal" 
       android:layout_marginTop="20dp" 
       android:ems="10" 
       android:hint="@string/descreva_o_problema" 
       android:inputType="textMultiLine" /> 

      <Button 
       android:id="@+id/buttonSend" 
       android:layout_width="300dp" 
       android:layout_height="wrap_content" 
       android:layout_gravity="center_vertical|center_horizontal|center" 
       android:layout_marginTop="44dp" 
       android:background="@color/colorPrimary" 
       android:gravity="center" 
       android:text="@string/enviar" 
       android:textColor="@android:color/white" 
       android:textStyle="bold" /> 

     </LinearLayout> 
    </ScrollView> 
</RelativeLayout> 

エラー

11-22 16:43:00.148 30210-30210/? E/Zygote: MountEmulatedStorage() 
11-22 16:43:00.148 30210-30210/? E/Zygote: v2 
11-22 16:43:00.158 30210-30210/? E/SELinux: [DEBUG] get_category: variable seinfo: default sensitivity: NULL, cateogry: NULL 
11-22 16:43:03.198 30210-30210/info.androidhive.materialtabs E/AndroidRuntime: FATAL EXCEPTION: main 
                       Process: info.androidhive.materialtabs, PID: 30210 
                       java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.view.View.findViewById(int)' on a null object reference 
                        at info.androidhive.materialtabs.fragments.OneFragment.onCreateView(OneFragment.java:60) 
                        at android.support.v4.app.Fragment.performCreateView(Fragment.java:1962) 
                        at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1067) 
                        at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1248) 
                        at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:738) 
                        at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1613) 
                        at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:570) 
                        at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:141) 
                        at android.support.v4.view.ViewPager.populate(ViewPager.java:1106) 
                        at android.support.v4.view.ViewPager.populate(ViewPager.java:952) 
                        at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1474) 
                        at android.view.View.measure(View.java:18425) 
                        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5802) 
                        at android.support.design.widget.CoordinatorLayout.onMeasureChild(CoordinatorLayout.java:607) 
                        at android.support.design.widget.CoordinatorLayout.onMeasure(CoordinatorLayout.java:674) 
                        at android.view.View.measure(View.java:18425) 
                        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5802) 
                        at android.widget.FrameLayout.onMeasure(FrameLayout.java:430) 
                        at android.support.v7.internal.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:124) 
                        at android.view.View.measure(View.java:18425) 
                        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5802) 
                        at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1835) 
                        at android.widget.LinearLayout.measureVertical(LinearLayout.java:725) 
                        at android.widget.LinearLayout.onMeasure(LinearLayout.java:616) 
                        at android.view.View.measure(View.java:18425) 
                        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5802) 
                        at android.widget.FrameLayout.onMeasure(FrameLayout.java:430) 
                        at android.view.View.measure(View.java:18425) 
                        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5802) 
                        at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1835) 
                        at android.widget.LinearLayout.measureVertical(LinearLayout.java:725) 
                        at android.widget.LinearLayout.onMeasure(LinearLayout.java:616) 
                        at android.view.View.measure(View.java:18425) 
                        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5802) 
                        at android.widget.FrameLayout.onMeasure(FrameLayout.java:430) 
                        at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2881) 
                        at android.view.View.measure(View.java:18425) 
                        at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2237) 
                        at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1295) 
                        at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1537) 
                        at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1180) 
                        at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6558) 
                        at android.view.Choreographer$CallbackRecord.run(Choreographer.java:777) 
                        at android.view.Choreographer.doCallbacks(Choreographer.java:590) 
                        at android.view.Choreographer.doFrame(Choreographer.java:560) 
                        at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:763) 
                        at android.os.Handler.handleCallback(Handler.java:739) 
                        at android.os.Handler.dispatchMessage(Handler.java:95) 
                        at android.os.Looper.loop(Looper.java:145) 
                        at android.app.ActivityThread.main(ActivityThread.java:5832) 
                        at java.lang.reflect.Method.invoke(Native Method) 
                        at java.lang.reflect.Method.invoke(Method.java:372) 
                        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1399) 
                        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1194) 

Answer 1

あなたのビューではありませんフラグメントのonCreate()メソッドで膨らんだ。 は、このようなonCreateView 例としてaproppiateライフサイクル方法であなたのウィジェットを初期化します。

@Override 
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) { 
    View rootView = inflater.inflate(<your.custom.layout>, container, false); 
    editTextMessage = rootView.findViewById(R.id.editTextMessage); 
    buttonSend = rootView.findViewById(R.id.buttonSend); 

    //Adding click listener 
    buttonSend.setOnClickListener(this) 
    return rootView; 
} 

Hereあなたは断片ライフサイクルを理解することができます。