访问其子项中的editText时，ListView空指针异常

Question

我在listview中获取editText的值时遇到问题。 logcat说我有一个Nullpointerexception。在做一些关于它的研究时发现，在我的代码中它只获得listview的可见子项的索引。任何人都可以帮我这个吗？我想要的是获取listview中所有editText的值。这是我的代码

SQLiteDatabase db = databaseHandler.getWritableDatabase();
                db.beginTransaction();

                int counter = 0;
                for(HashMap<String, String> map : mylist)
                {
                    ContentValues cv = new ContentValues();
                    String string = "";
                    for (int i = 0; i < lv_AttachedFileData.getCount(); i++)
                    {
                        if (i == counter)
                        {
                            View view=lv_AttachedFileData.getChildAt(i);

                            EditText editText=(EditText) view.findViewById(R.id.txt_iDesc);
                            string = editText.getText().toString();

                            cv.put(Constants.ATTACH_REPORTCODE, ReportCode);
                            cv.put(Constants.ATTACH_FILENAME, map.get(FILE_NAME));
                            cv.put(Constants.ATTACH_DESCRIPTION, string);
                            cv.put(Constants.ATTACH_FILELOCATION, map.get(FILE_URI));
                            cv.put(Constants.ATTACH_CREATEDBY, map.get(UPLOADED_BY));
                            cv.put(Constants.ATTACH_DATECREATED, map.get(DATE_UPLOADED));
                            db.insert(Constants.TABLE_ATTACH, null, cv);
                        }   
                    }                   
                        counter++;
                    }

                    db.setTransactionSuccessful();
                    db.endTransaction();
                    db.close();

这是我的logcat：

07-22 10:18:43.000: E/AndroidRuntime(9001): FATAL EXCEPTION: main
07-22 10:18:43.000: E/AndroidRuntime(9001): java.lang.NullPointerException
07-22 10:18:43.000: E/AndroidRuntime(9001):     at ph.com.ex.ireport.S_10th_IReportMain$6.onClick(S_10th_IReportMain.java:597)
07-22 10:18:43.000: E/AndroidRuntime(9001):     at   android.view.View.performClick(View.java:3131)
07-22 10:18:43.000: E/AndroidRuntime(9001):     at android.view.View$PerformClick.run(View.java:12035)
07-22 10:18:43.000: E/AndroidRuntime(9001):     at android.os.Handler.handleCallback(Handler.java:587)
07-22 10:18:43.000: E/AndroidRuntime(9001):     at android.os.Handler.dispatchMessage(Handler.java:92)
07-22 10:18:43.000: E/AndroidRuntime(9001):     at android.os.Looper.loop(Looper.java:132)
07-22 10:18:43.000: E/AndroidRuntime(9001):     at android.app.ActivityThread.main(ActivityThread.java:4123)
07-22 10:18:43.000: E/AndroidRuntime(9001):     at java.lang.reflect.Method.invokeNative(Native Method)
07-22 10:18:43.000: E/AndroidRuntime(9001):     at java.lang.reflect.Method.invoke(Method.java:491)
07-22 10:18:43.000: E/AndroidRuntime(9001):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:844)
07-22 10:18:43.000: E/AndroidRuntime(9001):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:602)
07-22 10:18:43.000: E/AndroidRuntime(9001):     at dalvik.system.NativeStart.main(Native Method)