1

当我得到一个在 ListView 中包含多个值的数组时出现错误...它崩溃了...

str_amparticipant_firstname 是一个字符串值数组。str_pmparticipant_firstname 也是一个字符串值数组。

 adapteram = new ArrayAdapter<String>(Attend.this, android.R.layout.simple_list_item_1, str_amparticipant_firstname);   

 adapterpm = new ArrayAdapter<String>(Attend.this, android.R.layout.simple_list_item_1, str_pmparticipant_firstname);   

          amattendees.setAdapter(adapteram);
          pmattendees.setAdapter(adapterpm);

该课程称为参加。当数组中有一个值时，ListViews 会显示数组中的值。如果有多个值，应用程序就会崩溃。我已经检查了数组是否被正确填充，并且是正确的。希望错误日志有答案。我得到的错误日志如下：

04-16 19:28:57.664: E/AndroidRuntime(5807): FATAL EXCEPTION: main
04-16 19:28:57.664: E/AndroidRuntime(5807): java.lang.NullPointerException
04-16 19:28:57.664: E/AndroidRuntime(5807):     at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:355)
04-16 19:28:57.664: E/AndroidRuntime(5807):     at android.widget.ArrayAdapter.getView(ArrayAdapter.java:323)
04-16 19:28:57.664: E/AndroidRuntime(5807):     at android.widget.AbsListView.obtainView(AbsListView.java:1430)
04-16 19:28:57.664: E/AndroidRuntime(5807):     at android.widget.ListView.measureHeightOfChildren(ListView.java:1307)
04-16 19:28:57.664: E/AndroidRuntime(5807):     at android.widget.ListView.onMeasure(ListView.java:1127)
04-16 19:28:57.664: E/AndroidRuntime(5807):     at android.view.View.measure(View.java:8510)
04-16 19:28:57.664: E/AndroidRuntime(5807):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3202)
04-16 19:28:57.664: E/AndroidRuntime(5807):     at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1017)
04-16 19:28:57.664: E/AndroidRuntime(5807):     at android.widget.LinearLayout.measureHorizontal(LinearLayout.java:701)
04-16 19:28:57.664: E/AndroidRuntime(5807):     at android.widget.LinearLayout.onMeasure(LinearLayout.java:311)
04-16 19:28:57.664: E/AndroidRuntime(5807):     at android.view.View.measure(View.java:8510)
04-16 19:28:57.664: E/AndroidRuntime(5807):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3202)
04-16 19:28:57.664: E/AndroidRuntime(5807):     at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1017)
04-16 19:28:57.664: E/AndroidRuntime(5807):     at android.widget.LinearLayout.measureVertical(LinearLayout.java:386)
04-16 19:28:57.664: E/AndroidRuntime(5807):     at android.widget.LinearLayout.onMeasure(LinearLayout.java:309)
04-16 19:28:57.664: E/AndroidRuntime(5807):     at android.view.View.measure(View.java:8510)
04-16 19:28:57.664: E/AndroidRuntime(5807):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3202)
04-16 19:28:57.664: E/AndroidRuntime(5807):     at android.widget.FrameLayout.onMeasure(FrameLayout.java:250)
04-16 19:28:57.664: E/AndroidRuntime(5807):     at android.view.View.measure(View.java:8510)
04-16 19:28:57.664: E/AndroidRuntime(5807):     at android.widget.LinearLayout.measureVertical(LinearLayout.java:531)
04-16 19:28:57.664: E/AndroidRuntime(5807):     at android.widget.LinearLayout.onMeasure(LinearLayout.java:309)
04-16 19:28:57.664: E/AndroidRuntime(5807):     at android.view.View.measure(View.java:8510)
04-16 19:28:57.664: E/AndroidRuntime(5807):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3202)
04-16 19:28:57.664: E/AndroidRuntime(5807):     at android.widget.FrameLayout.onMeasure(FrameLayout.java:250)
04-16 19:28:57.664: E/AndroidRuntime(5807):     at android.view.View.measure(View.java:8510)
04-16 19:28:57.664: E/AndroidRuntime(5807):     at android.view.ViewRoot.performTraversals(ViewRoot.java:871)
04-16 19:28:57.664: E/AndroidRuntime(5807):     at android.view.ViewRoot.handleMessage(ViewRoot.java:1921)
04-16 19:28:57.664: E/AndroidRuntime(5807):     at android.os.Handler.dispatchMessage(Handler.java:99)
04-16 19:28:57.664: E/AndroidRuntime(5807):     at android.os.Looper.loop(Looper.java:143)
04-16 19:28:57.664: E/AndroidRuntime(5807):     at android.app.ActivityThread.main(ActivityThread.java:4196)
04-16 19:28:57.664: E/AndroidRuntime(5807):     at java.lang.reflect.Method.invokeNative(Native Method)
04-16 19:28:57.664: E/AndroidRuntime(5807):     at java.lang.reflect.Method.invoke(Method.java:507)
04-16 19:28:57.664: E/AndroidRuntime(5807):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
04-16 19:28:57.664: E/AndroidRuntime(5807):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
04-16 19:28:57.664: E/AndroidRuntime(5807):     at dalvik.system.NativeStart.main(Native Method)

再次，仅当数组中有多个值时才会出现错误。我试图找到这个问题的答案，但我找不到有关该错误的任何信息。请帮忙！谢谢你！

更新：这是填充和创建数组的方式：

for(int i = 0; i < json_array_amparticipants.length(); i++){
                             //store all the amparticipants
                         str_amparticipant_email = new String[json_array_amparticipants.length()];
                         str_amparticipant_firstname = new String[json_array_amparticipants.length()];
                         str_amparticipant_lastname = new String[json_array_amparticipants.length()];         
                         str_amparticipant_attendingam = new String[json_array_amparticipants.length()];    
                         str_amparticipant_attendingpm = new String[json_array_amparticipants.length()];
                         //full_name_am = new String[json_array_amparticipants.length()];
                         str_amparticipant_email[i] = json_array_amparticipants.getJSONObject(i).getString("email");
                         str_amparticipant_firstname[i] = json_array_amparticipants.getJSONObject(i).getString("first_name");
                         str_amparticipant_lastname[i] = json_array_amparticipants.getJSONObject(i).getString("last_name"); 
                         str_amparticipant_attendingam[i] = json_array_amparticipants.getJSONObject(i).getString("attending_am");   
                         str_amparticipant_attendingpm[i] = json_array_amparticipants.getJSONObject(i).getString("attending_pm");
                         //full_name_am[i] = str_amparticipant_firstname[i] + str_amparticipant_lastname[i];

                     }

修复：我每次都在创建新数组，所以它仍然存储值，但它会导致崩溃......这是更新的修复。伙计们干杯：

   //store all the amparticipants
             str_amparticipant_email = new String[json_array_amparticipants.length()];
             str_amparticipant_firstname = new String[json_array_amparticipants.length()];
             str_amparticipant_lastname = new String[json_array_amparticipants.length()];         
             str_amparticipant_attendingam = new String[json_array_amparticipants.length()];    
             str_amparticipant_attendingpm = new String[json_array_amparticipants.length()];


                 for(int i = 0; i < json_array_amparticipants.length(); i++){
                     //full_name_am = new String[json_array_amparticipants.length()];
                     str_amparticipant_email[i] = json_array_amparticipants.getJSONObject(i).getString("email");
                     str_amparticipant_firstname[i] = json_array_amparticipants.getJSONObject(i).getString("first_name");
                     str_amparticipant_lastname[i] = json_array_amparticipants.getJSONObject(i).getString("last_name"); 
                     str_amparticipant_attendingam[i] = json_array_amparticipants.getJSONObject(i).getString("attending_am");   
                     str_amparticipant_attendingpm[i] = json_array_amparticipants.getJSONObject(i).getString("attending_pm");
                     //full_name_am[i] = str_amparticipant_firstname[i] + str_amparticipant_lastname[i];

                 }
4

2 回答 2

4

这应该在您的循环之外：

                         str_amparticipant_email = new String[json_array_amparticipants.length()];
                         str_amparticipant_firstname = new String[json_array_amparticipants.length()];
                         str_amparticipant_lastname = new String[json_array_amparticipants.length()];         
                         str_amparticipant_attendingam = new String[json_array_amparticipants.length()];    
                         str_amparticipant_attendingpm = new String[json_array_amparticipants.length()];

每次进入循环时，您都在重新创建数组，删除任何以前的值。

于 2012-04-16T19:05:42.447 回答
1

我的猜测是这个错误在这里：

str_amparticipant_firstname[i] = json_array_amparticipants.getJSONObject(i).getString("first_name"); str_amparticipant_lastname[i] = json_array_amparticipants.getJSONObject(i).getString("last_name");

这些键是否可能不在 JSONObject 中？它将解释空指针异常。

于 2012-04-16T19:07:06.347 回答