Nullpointer异常在片段布局

Question

我敢肯定，我错过了一些非常简单的东西，但由于某种原因运行这段代码我得到空指针异常。有谁知道为什么？

11-27 20:27:30.568: E/AndroidRuntime(32479): FATAL EXCEPTION: main 
11-27 20:27:30.568: E/AndroidRuntime(32479): Process: com.example.makemyday, PID: 32479 
11-27 20:27:30.568: E/AndroidRuntime(32479): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.makemyday/com.example.makemyday.ActionDetailActivity}: java.lang.NullPointerException 
11-27 20:27:30.568: E/AndroidRuntime(32479): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2176) 
11-27 20:27:30.568: E/AndroidRuntime(32479): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2226) 
11-27 20:27:30.568: E/AndroidRuntime(32479): at android.app.ActivityThread.access$700(ActivityThread.java:135) 
11-27 20:27:30.568: E/AndroidRuntime(32479): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1397) 
11-27 20:27:30.568: E/AndroidRuntime(32479): at android.os.Handler.dispatchMessage(Handler.java:102) 
11-27 20:27:30.568: E/AndroidRuntime(32479): at android.os.Looper.loop(Looper.java:137) 
11-27 20:27:30.568: E/AndroidRuntime(32479): at android.app.ActivityThread.main(ActivityThread.java:4998) 
11-27 20:27:30.568: E/AndroidRuntime(32479): at java.lang.reflect.Method.invokeNative(Native Method) 
11-27 20:27:30.568: E/AndroidRuntime(32479): at java.lang.reflect.Method.invoke(Method.java:515) 
11-27 20:27:30.568: E/AndroidRuntime(32479): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:777) 
11-27 20:27:30.568: E/AndroidRuntime(32479): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:593) 
11-27 20:27:30.568: E/AndroidRuntime(32479): at dalvik.system.NativeStart.main(Native Method) 
11-27 20:27:30.568: E/AndroidRuntime(32479): Caused by: java.lang.NullPointerException 
11-27 20:27:30.568: E/AndroidRuntime(32479): at com.example.makemyday.EventDetailsFragment.onCreateView(EventDetailsFragment.java:34) 
11-27 20:27:30.568: E/AndroidRuntime(32479): at android.support.v4.app.Fragment.performCreateView(Fragment.java:1500) 
11-27 20:27:30.568: E/AndroidRuntime(32479): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:927) 
11-27 20:27:30.568: E/AndroidRuntime(32479): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1104) 
11-27 20:27:30.568: E/AndroidRuntime(32479): at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:682) 
11-27 20:27:30.568: E/AndroidRuntime(32479): at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1467) 
11-27 20:27:30.568: E/AndroidRuntime(32479): at android.support.v4.app.FragmentActivity.onStart(FragmentActivity.java:570) 

fragment_event_detail.xml

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:tools="http://schemas.android.com/tools" 
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent" 
    android:orientation="vertical" > 

    <ScrollView 
     android:layout_width="fill_parent" 
     android:layout_height="132dp" > 

     <EditText 
      android:id="@+id/event_description" 
      android:layout_width="fill_parent" 
      android:layout_height="wrap_content" 
      android:ems="10" 
      android:hint="@string/hint_description" 
      android:inputType="text" 
      android:padding="16dp" 
      android:textIsSelectable="true" 
      android:scrollbars = "vertical" 
      android:lines="4" 
      android:textSize="14sp" /> 
    </ScrollView> 

    <LinearLayout 
     android:layout_width="match_parent" 
     android:layout_height="wrap_content" 
     android:orientation="horizontal" 
     android:paddingLeft="0dip" 
     android:paddingRight="0dip" > 

     <EditText 
      android:id="@+id/quantity" 
      android:layout_width="166dp" 
      android:layout_height="wrap_content" 
      android:padding="16dp" 
      android:textIsSelectable="true" 
      /> 

     <Spinner 
      android:id="@+id/category_quantity" 
      android:layout_width="0dp" 
      android:layout_height="match_parent" 
      android:layout_weight="0.01" 
      android:textSize="14dip" /> 
    </LinearLayout> 

    <LinearLayout 
     android:layout_width="match_parent" 
     android:layout_height="wrap_content" 
     android:orientation="horizontal" 
     android:paddingLeft="0dip" 
     android:paddingRight="0dip" > 

     <Spinner 
      android:id="@+id/category_query" 
      android:layout_width="0dp" 
      android:layout_height="match_parent" 
      android:layout_weight="0.01" 
      android:textSize="14dip" /> 
    </LinearLayout> 
</LinearLayout> 

EventDetailsFragment

package com.example.makemyday; 

    import android.os.Bundle; 
    import android.support.v4.app.Fragment; 
    import android.view.LayoutInflater; 
    import android.view.View; 
    import android.view.ViewGroup; 
    import android.widget.AdapterView; 
    import android.widget.ArrayAdapter; 
    import android.widget.EditText; 
    import android.widget.Spinner; 
    import android.widget.TextView; 

import android.widget.AdapterView.OnItemSelectedListener; 

public class EventDetailsFragment extends Fragment implements OnItemSelectedListener{ 

    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
      Bundle savedInstanceState) { 
     View rootView = inflater.inflate(R.layout.fragment_action_detail, 
       container, false); 

     // Show the dummy content as text in a TextView. 

      Spinner category=(Spinner)rootView.findViewById(R.id.category_query); 
      ArrayAdapter<CharSequence> adapterCategory = ArrayAdapter.createFromResource(this.getActivity().getBaseContext(),R.array.category_names, android.R.layout.simple_spinner_item); 
      adapterCategory.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); 
      category.setAdapter(adapterCategory); 
      category.setOnItemSelectedListener(this); 

      Spinner quantity=(Spinner)rootView.findViewById(R.id.category_quantity); 
      ArrayAdapter<CharSequence> adapterQuantity = ArrayAdapter.createFromResource(this.getActivity().getBaseContext(),R.array.quantity_names, android.R.layout.simple_spinner_item); 
      adapterQuantity.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); 
      quantity.setAdapter(adapterQuantity); 
      quantity.setOnItemSelectedListener(this); 

      EditText description = (EditText)rootView.findViewById(R.id.event_description); 
      description.setText("this"); 

     return rootView; 
    } 


    public void onItemSelected(AdapterView<?> arg0, View arg1, int arg2, 
      long arg3) { 
     // TODO Auto-generated method stub 

    } 

    public void onNothingSelected(AdapterView<?> arg0) { 
     // TODO Auto-generated method stub 

    } 
} 

Answer 1

你显示一个名为fragment_event_detail.xml布局，但你虚增布局命名R.layout.fragment_action_detail。检查下面的你onCreate()

View rootView = inflater.inflate(R.layout.fragment_action_detail, 
      container, false); 

线像下面替换布局，

View rootView = inflater.inflate(R.layout.fragment_event_detail, 
       container, false);