java.lang.RuntimeException: Невозможно начать работу

Question

Мое приложение всегда сбой при запуске. Это ошибка в Android Monitor. Следующий код из моего фрагмента, который должен начинаться в начале приложения:

01-30 23:42:55.281 5767-5767/silverbeach.meintieralter E/AndroidRuntime: FATAL EXCEPTION: main 
                     Process: silverbeach.meintieralter, PID: 5767 
                     java.lang.RuntimeException: Unable to start activity ComponentInfo{silverbeach.meintieralter/silverbeach.meintieralter.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference 
                      at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3254) 
                      at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3350) 
                      at android.app.ActivityThread.access$1100(ActivityThread.java:222) 
                      at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1795) 
                      at android.os.Handler.dispatchMessage(Handler.java:102) 
                      at android.os.Looper.loop(Looper.java:158) 
                      at android.app.ActivityThread.main(ActivityThread.java:7229) 
                      at java.lang.reflect.Method.invoke(Native Method) 
                      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230) 
                      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120) 
                      Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference 
                      at silverbeach.meintieralter.FragmentOne.onCreate(FragmentOne.java:36) 
                      at android.app.Fragment.performCreate(Fragment.java:2242) 
                      at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:947) 
                      at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1163) 
                      at android.app.BackStackRecord.run(BackStackRecord.java:793) 
                      at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1552) 
                      at android.app.FragmentController.execPendingActions(FragmentController.java:325) 
                      at android.app.Activity.performStart(Activity.java:6914) 
                      at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3217) 
                      at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3350)  
                      at android.app.ActivityThread.access$1100(ActivityThread.java:222)  
                      at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1795)  
                      at android.os.Handler.dispatchMessage(Handler.java:102)  
                      at android.os.Looper.loop(Looper.java:158)  
                      at android.app.ActivityThread.main(ActivityThread.java:7229)  
                      at java.lang.reflect.Method.invoke(Native Method)  
                      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230)  
                      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)  
01-30 23:42:55.401 5767-5767/silverbeach.meintieralter I/Process: Sending signal. PID: 5767 SIG: 9 

код

package silverbeach.meintieralter; 

import android.app.Fragment; 
import android.content.Context; 
import android.os.Bundle; 
import android.os.Vibrator; 
import android.support.annotation.Nullable; 
import android.support.design.widget.Snackbar; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.Button; 
import android.widget.EditText; 
import android.widget.Spinner; 
import android.widget.TextView; 
import android.view.View.OnClickListener; 

import static android.content.Context.VIBRATOR_SERVICE; 

public class FragmentOne extends Fragment { 

private TextView out; 
private EditText alter; 
private Spinner s; 
private Button button; 



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



    button.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View v) { 




      String text = s.getSelectedItem().toString(); 
      int newage = 404; 
      double doublenewage = 4.04; 
      double doubleage; 
      int intage; 
      doubleage = Double.parseDouble(alter.getText().toString()); 
      intage = (int) doubleage; 

      switch (text) { 
       case "Pferd": { 
        doublenewage = intage/3.1; 
        long longpferdage = Math.round(doublenewage); 
        newage = (int) longpferdage; 

        if (newage < 31) 
         out.setText("Du bist ein " + Integer.toString(newage) + " Jahre altes Pferd"); 
        else 
         out.setText("Du bist höchstwahrscheinlich schon tot, aber theoretisch wärst du ein " + newage + "-Jähriges Pferd."); 
       }break; 
       case "Hund": { 
        newage = intage/7; 
        if (newage < 15) 

         out.setText("Du bist ein " + Integer.toString(newage) + " Jahre alter Hund."); 
        else 
         out.setText("Du bist höchstwahrscheinlich schon tot, aber theoretisch wärst du ein " + newage + "-Jähriger Hund."); 

       }break; 
       case "Meerschweinchen": { 
        newage = intage/12; 
        if (newage < 8) 

         //out.setText("Du bist ein " + Integer.toString(newage) + " Jahre altes Meerie."); 

         out.setText("Du bist ein "+Integer.toString(newage)+" Jahre altes Meerie."); 





        else 
         out.setText("Du bist höchstwahrscheinlich schon tot, aber theoretisch wärst du ein " + newage + "-Jähriges Meerie."); 

       }break; 


      } 



     } 


    }); 

} 





@Nullable 
@Override 
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 

    View layout = inflater.inflate(R.layout.fragment_one, null); 

    out = (TextView) layout.findViewById(R.id.out); 
    alter = (EditText) layout.findViewById(R.id.altereingabe); 
    s = (Spinner) layout.findViewById(R.id.spinner); 
    button = (Button) layout.findViewById(R.id.button); 

    // tvText1 = (TextView) layout.findViewById(R.id.tvFragmentOne); 

    return layout; 
} 

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

    //tvText1.setText("Ok View 1 wurde geändert."); 

} 

}

Answer 1

onCreate называется ПЕРЕДonCreateView, таким образом, в момент назначения слушателя для просмотра, его еще нуль;

Итак, предлагаю переместить button.setOnClickListener на номер onCreateView(). метод

Answer 2

button равна нулю в этой точке. Перед установкой прослушивателя вам необходимо будет использовать button = (Button)findViewById(R.id.<id of the button>).