NullPointerException爲什麼？

Question

我需要一些幫助。下面應該是你需要的。

的logcat（更新）/

04-17 11:31:07.836: E/AndroidRuntime(1400): FATAL EXCEPTION: main 
04-17 11:31:07.836: E/AndroidRuntime(1400): java.lang.NullPointerException 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at pl.smarterp2.ZamowienieAdd$sec_Fragment_zp.Clicker(ZamowienieAdd.java:1450) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at pl.smarterp2.ZamowienieAdd$sec_Fragment_zp.onCreateView(ZamowienieAdd.java:1465) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at android.support.v4.app.Fragment.performCreateView(Fragment.java:1500) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:927) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1104) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:682) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1467) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:472) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:141) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at android.support.v4.view.ViewPager.populate(ViewPager.java:1068) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at android.support.v4.view.ViewPager.populate(ViewPager.java:914) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1436) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at android.view.View.measure(View.java:15172) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:617) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:399) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at android.view.View.measure(View.java:15172) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:617) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:399) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at android.view.View.measure(View.java:15172) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at android.support.v4.widget.DrawerLayout.onMeasure(DrawerLayout.java:651) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at android.view.View.measure(View.java:15172) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4816) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at android.widget.FrameLayout.onMeasure(FrameLayout.java:310) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at android.view.View.measure(View.java:15172) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at android.widget.LinearLayout.measureVertical(LinearLayout.java:833) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at android.widget.LinearLayout.onMeasure(LinearLayout.java:574) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at android.view.View.measure(View.java:15172) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4816) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at android.widget.FrameLayout.onMeasure(FrameLayout.java:310) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2148) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at android.view.View.measure(View.java:15172) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1850) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1102) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1275) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1000) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4214) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at android.view.Choreographer$CallbackRecord.run(Choreographer.java:725) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at android.view.Choreographer.doCallbacks(Choreographer.java:555) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at android.view.Choreographer.doFrame(Choreographer.java:525) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:711) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at android.os.Handler.handleCallback(Handler.java:615) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at android.os.Handler.dispatchMessage(Handler.java:92) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at android.os.Looper.loop(Looper.java:137) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at android.app.ActivityThread.main(ActivityThread.java:4745) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at java.lang.reflect.Method.invokeNative(Native Method) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at java.lang.reflect.Method.invoke(Method.java:511) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 
04-17 11:31:07.836: E/AndroidRuntime(1400):  at dalvik.system.NativeStart.main(Native Method) 

代碼（更新）/

public static class sec_Fragment_zp extends Fragment{ 

     public static final String ARG_SECTION_NUMBER = "section_number"; 

     public sec_Fragment_zp() { } 

     //ListView lv = setContentView(); 
     public void Clicker() 
     { 
      View lView = this.getView(); 
      final ListView lista_zam = (ListView) lView.findViewById(R.id.zamadd_lista); 

      lista_zam.setOnClickListener(new OnClickListener(){ 

       @Override 
       public void onClick(View v) 
       { 
        lista_zam.setBackgroundResource(R.drawable.zaplacono); 
       } 
      }); 
     } 

      @Override 
      public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 
       View myLayout = inflater.inflate(R.layout.activity_zamowienie_fragment2, container, false);  
       Clicker(); 
       return myLayout;  
      } 

我不明白爲什麼它不工作。

只要我只是想點擊列表項後更改背景。這不是我的項目，只是在做一些改變。如果你想要更多的代碼問（我有一堆）。我不知道爲什麼它不適合我。

Answer 1

空指針是這裏

final View lView = this.getView(); 

因爲Clicker(container);會先調用創建view.So變化

@Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 
     Clicker(container); 
     return inflater.inflate(R.layout.activity_zamowienie_fragment2, container, false);   
    } 

到

@Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 
     View myLayout = inflater.inflate(R.layout.activity_zamowienie_fragment2, container, false);  
     Clicker(container); 
     return myLayout;  
    }