Android Java objModelClass.getClass().getDeclaredFields()返回"$ change"作为一个字段

Question

在我们的项目中,我们使用数据模型来存储从服务接收的数据.因此,在我们将数据插入数据库的特定情况下,我们使用objModelClass.getClass().getDeclaredFields()方法来获取所有字段名称,并且它正确地返回该类的所有字段名称,但也返回一个带有名称的额外字段"$ change",在课堂上不存在.

奇怪的是,在Android工作室中没有这样的问题但是当我们升级到android studio 2.0时就发生了这种情况.

虽然我已经应用了快速修复,但我需要正确解决这个问题.我想知道它为什么会发生？

这个函数使用这个方法

public void insertValuesIntoTable(final String strTableName, ArrayList<Object> alObjClasses,
                                      String strPrimaryKey, String strCompositeKey) {
        try {
            SQLiteDatabase db_w = this.getWritableDatabase();
            ContentValues contentValues = new ContentValues();
            //Iterate through every model class Object in the ArrayList and transfer the contents to the DB
            if (alObjClasses != null)
                for (Object objModelClass : alObjClasses) {
                    for (Field field : objModelClass.getClass().getDeclaredFields()) {
                        //Encrypt value if encryption is enabled & the column is to be encrypted
                        try {
                            field.setAccessible(true);
                            //Test if the table received is Ignore contacts. Minor Hack inserted
                            //So that the same contact data model can be re used. It checks if the
                            //Table is of ignored constant or not then checks if the column exists
                            //in the table or not as that of the field name. Doing this saves
                            //from receiving a SQLConstraint exception stating, "Column not found"
                            if(field.getName().equals("$change"))
                                continue;
                            if(strTableName.equalsIgnoreCase(ContactConstants.TABLE_IGNORED_CONTACTS))
                                if(!field.getName().equalsIgnoreCase(ContactConstants.TABLE_IGNORED_CONTACTS_NAMES)
                                        && !field.getName().equalsIgnoreCase(ContactConstants.TABLE_IGNORED_CONTACTS_NUMBERS)
                                        && !field.getName().equalsIgnoreCase(ContactConstants.TABLE_IGNORED_CONTACTS_EMAIL)
                                        && !field.getName().equalsIgnoreCase(ContactConstants.TABLE_IGNORED_CONTACTS_CITY)
                                        && !field.getName().equalsIgnoreCase(ContactConstants.TABLE_IGNORED_CONTACTS_ID))
                                    continue;
                            contentValues.put(field.getName(),
                                    (Constants.ENCRYPTION_PREFERENCE && HelperFunctions.isColumnEncrypted(field.getName()))
                                            ? HelperFunctions.encryptString((String) field.get(objModelClass))
                                            : (String) field.get(objModelClass));
                        } catch (IllegalAccessException e) {
                         //   e.printStackTrace();
                            //Never thrown since field.setAccessible(true); is called before accessing data
                        }
                        catch ( ClassCastException e) {
                   //         e.printStackTrace();
                            //Never thrown since field.setAccessible(true); is called before accessing data
                        }
                    }
                    try {
                        if (db_w.insert(strTableName, null, contentValues) == -1)
                            throw new SQLiteConstraintException();
                    } catch (SQLiteConstraintException e) {
                       // e.printStackTrace();
                        Log.i("Error - DB", "Error occurred while trying to add data to "
                                + strTableName + " Table, updating data instead.");
                        //Since the entry exists in the DB, it will be updated instead
                        updateEntryInDatabase(db_w, strTableName, strPrimaryKey, strCompositeKey, contentValues);
                    }
                }
            db_w.close();
        } catch (NullPointerException e) {
         //   e.printStackTrace();
            //Is thrown sometimes when the context of the activity which called it is destroyed mid execution
        }
        catch (SQLiteException e) {
         //   e.printStackTrace();
            //Is thrown sometimes when the context of the activity which called it is destroyed mid execution
        }
    }

Answer 1

从今天早上起我就在努力解决这个问题.这是由于Android Studio 2的新功能,即即时运行,它在某个地方添加了这个字段,因为它可以在调试时看到:它实现了界面com.android.tools.fd.runtime.IncrementalChange.

可以通过使用isSynthetic()方法检查字段来解决此问题:它将返回true运行时生成的字段$change,false否则.