使用微調控制器時會引發神祕的NullPointerException

我有一個可點擊的TextView和一個微調器，其可見性設置爲GONE。使用微調控制器時會引發神祕的NullPointerException

這是我的佈局片段：

<TextView 
    android:id="@+id/strip1" 
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text=" Order Name  ID  Description  Type" 
    android:textSize="15dip" 
    android:textStyle="bold" 
    android:clickable="true" 
    android:gravity="left" 
    android:textColor="#ffffff" 
    android:layout_weight="1" /> 

<Spinner android:id="@+id/sortSpinner" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:drawSelectorOnTop="true" 
    android:visibility="gone" 
    android:clickable="true" 
    android:prompt="@string/prompt" />

在onCreate我有這樣的：

TextView strip = (TextView)findViewById(R.id.strip1); 
strip.setOnClickListener(new OnClickListener() { 

    public void onClick(View arg0) { 
     spinner_show(); 
    } 

});

spinner_show()看起來是這樣的：

private void spinner_show() { 

    String str = new String[2]; 
    str[0] = "Ascending"; 
    str[1] = "Descending"; 

    Spinner sortSpin = (Spinner)findViewById(R.id.sortSpinner); 
    ArrayAdapter<String> sizeArrayAdapter = 
     new ArrayAdapter<String>(this, 
       android.R.layout.simple_spinner_item, str); 
    sizeArrayAdapter.setDropDownViewResource(
     android.R.layout.simple_spinner_dropdown_item); 
    sortSpin.setAdapter(sizeArrayAdapter); 
    sortSpin.setOnItemSelectedListener(
     new AdapterView.OnItemSelectedListener() { 
      public void onItemSelected(AdapterView<?> parent, 
        View v, int pos, long id) { 

     } 

     public void onNothingSelected(AdapterView<?> parent) { 

     } 
    });

該應用程序是扔NullPointerException和我無法弄清楚爲什麼。

這裏是logcat的片段：

12-14 14:57:31.388: W/dalvikvm(3794): threadid=1: thread exiting with uncaught exception (group=0x40015560) 
12-14 14:57:31.468: E/AndroidRuntime(3794): FATAL EXCEPTION: main 
12-14 14:57:31.468: E/AndroidRuntime(3794): java.lang.NullPointerException 
12-14 14:57:31.468: E/AndroidRuntime(3794):  at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:355) 
12-14 14:57:31.468: E/AndroidRuntime(3794):  at android.widget.ArrayAdapter.getDropDownView(ArrayAdapter.java:376) 
12-14 14:57:31.468: E/AndroidRuntime(3794):  at android.widget.Spinner$DropDownAdapter.getDropDownView(Spinner.java:332) 
12-14 14:57:31.468: E/AndroidRuntime(3794):  at android.widget.Spinner$DropDownAdapter.getView(Spinner.java:328) 
12-14 14:57:31.468: E/AndroidRuntime(3794):  at android.widget.AbsListView.obtainView(AbsListView.java:1409) 
12-14 14:57:31.468: E/AndroidRuntime(3794):  at android.widget.ListView.measureHeightOfChildren(ListView.java:1216) 
12-14 14:57:31.468: E/AndroidRuntime(3794):  at android.widget.ListView.onMeasure(ListView.java:1127) 
12-14 14:57:31.468: E/AndroidRuntime(3794):  at android.view.View.measure(View.java:8313) 
12-14 14:57:31.468: E/AndroidRuntime(3794):  at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3138) 
12-14 14:57:31.468: E/AndroidRuntime(3794):  at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1017) 
12-14 14:57:31.468: E/AndroidRuntime(3794):  at android.widget.LinearLayout.measureVertical(LinearLayout.java:386) 
12-14 14:57:31.468: E/AndroidRuntime(3794):  at android.widget.LinearLayout.onMeasure(LinearLayout.java:309) 
12-14 14:57:31.468: E/AndroidRuntime(3794):  at android.view.View.measure(View.java:8313) 
12-14 14:57:31.468: E/AndroidRuntime(3794):  at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3138) 
12-14 14:57:31.468: E/AndroidRuntime(3794):  at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1017) 
12-14 14:57:31.468: E/AndroidRuntime(3794):  at android.widget.LinearLayout.measureVertical(LinearLayout.java:386) 
12-14 14:57:31.468: E/AndroidRuntime(3794):  at android.widget.LinearLayout.onMeasure(LinearLayout.java:309) 
12-14 14:57:31.468: E/AndroidRuntime(3794):  at com.android.internal.widget.WeightedLinearLayout.onMeasure(WeightedLinearLayout.java:60) 
12-14 14:57:31.468: E/AndroidRuntime(3794):  at android.view.View.measure(View.java:8313) 
12-14 14:57:31.468: E/AndroidRuntime(3794):  at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3138) 
12-14 14:57:31.468: E/AndroidRuntime(3794):  at android.widget.FrameLayout.onMeasure(FrameLayout.java:250) 
12-14 14:57:31.468: E/AndroidRuntime(3794):  at android.view.View.measure(View.java:8313) 
12-14 14:57:31.468: E/AndroidRuntime(3794):  at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3138) 
12-14 14:57:31.468: E/AndroidRuntime(3794):  at android.widget.FrameLayout.onMeasure(FrameLayout.java:250) 
12-14 14:57:31.468: E/AndroidRuntime(3794):  at android.view.View.measure(View.java:8313) 
12-14 14:57:31.468: E/AndroidRuntime(3794):  at android.view.ViewRoot.performTraversals(ViewRoot.java:839) 
12-14 14:57:31.468: E/AndroidRuntime(3794):  at android.view.ViewRoot.handleMessage(ViewRoot.java:1859) 
12-14 14:57:31.468: E/AndroidRuntime(3794):  at android.os.Handler.dispatchMessage(Handler.java:99) 
12-14 14:57:31.468: E/AndroidRuntime(3794):  at android.os.Looper.loop(Looper.java:123) 
12-14 14:57:31.468: E/AndroidRuntime(3794):  at android.app.ActivityThread.main(ActivityThread.java:3683) 
12-14 14:57:31.468: E/AndroidRuntime(3794):  at java.lang.reflect.Method.invokeNative(Native Method) 
12-14 14:57:31.468: E/AndroidRuntime(3794):  at java.lang.reflect.Method.invoke(Method.java:507) 
12-14 14:57:31.468: E/AndroidRuntime(3794):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839) 
12-14 14:57:31.468: E/AndroidRuntime(3794):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597) 
12-14 14:57:31.468: E/AndroidRuntime(3794):  at dalvik.system.NativeStart.main(Native Method)

我缺少什麼？

來源

2011-12-14 user1065490

請張貼錯誤日誌... – user370305 2011-12-14 09:09:24

運行在命令行中輸入「adb logcat AndroidRuntime：* *：S」，然後運行該應用程序。這將只顯示異常信息，然後在此處發佈。我認爲不應該發生的碰撞時，我做的一件事就是開始評論代碼，直到崩潰消失。至少你有和想法在哪裏看。從你的文章中，我們不知道它是在onCreate還是在你的spinner_show函數中崩潰。 – 2011-12-14 09:27:59

檢查堆棧跟蹤並查看引發異常的行號。 – 2011-12-14 09:31:12

OK，首先，你的XML佈局文件，

  <TextView 
    android:id="@+id/strip1" 
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text=" Order Name  ID  Description  Type" 
    android:textSize="15dip" 
    android:textStyle="bold" 
    android:clickable="true" 
    android:gravity="left" 
    android:textColor="#ffffff"/> 

<Spinner android:id="@+id/sortSpinner" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:drawSelectorOnTop="true" 
     android:visibility="gone" 
     android:clickable="true" 
     android:prompt="@string/prompt"/>

在XML文件中你的TextView有android:layout_weight="1"因此其覆蓋所有的佈局，對微調沒有足夠的空間（這也不會引起NullPointerException異常所以它不是必要的），

從Java類文件

現在，

private void spinner_show() 
    { 

     String[] str=new String[2]; // problem on declaring String array 
     str[0]="Ascending"; 
     str[1]="Descending"; 

     Spinner sortSpin = (Spinner)findViewById(R.id.sortSpinner); 
     ArrayAdapter<String> sizeArrayAdapter = new ArrayAdapter<String> (this,android.R.layout.simple_spinner_item,str); 
     sizeArrayAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); 
     sortSpin.setAdapter(sizeArrayAdapter); 
     sortSpin.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() { 
      public void onItemSelected(AdapterView<?> parent, View v, int pos, long id) { 

      } 
      public void onNothingSelected(AdapterView<?> parent) { 
      } 
     }); 

     sortSpin.setVisibility(View.VISIBLE); // also you don't Visiable your spinner 
    }

和主要的事情是在我的日食它的作品很好，我剛纔刪除android:prompt="@string/prompt"從XML文件屬性，因爲我沒有提示字符串..

來源

2011-12-14 10:00:58 user370305

因爲您已將Spinner的可見性視爲消失，那麼它如何能夠顯示您的微調器。

這麼叫sortSpin.SetVisibility(View.VISIBLE);

來源

2011-12-14 09:25:29

使用微調控制器時會引發神祕的NullPointerException

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