Gson无法在我的Android&;中调用no-args construktor for observer(LiveData);科特林项目
我已经读了很多stackoverflow的文章和其他关于它的博客文章,它们尝试了不同的解决方案来解决类似(但不相同)的问题 我将按如下方式安排这一职位:Gson无法在我的Android&;中调用no-args construktor for observer(LiveData);科特林项目,android,kotlin,gson,android-room,android-livedata,Android,Kotlin,Gson,Android Room,Android Livedata,我已经读了很多stackoverflow的文章和其他关于它的博客文章,它们尝试了不同的解决方案来解决类似(但不相同)的问题 我将按如下方式安排这一职位: 我的问题 我的代码(我认为相关的部分) 我试图修复的是什么 1.我的问题 我收到以下错误消息: Process: com.myapp, PID: 23553 java.lang.RuntimeException: Unable to invoke no-args constructor for androidx.arch.cor
Process: com.myapp, PID: 23553
java.lang.RuntimeException: Unable to invoke no-args constructor for androidx.arch.core.internal.SafeIterableMap$SupportRemove<androidx.lifecycle.Observer<? super java.lang.Integer>, androidx.lifecycle.LiveData$ObserverWrapper>. Registering an InstanceCreator with Gson for this type may fix this problem.
at com.google.gson.internal.ConstructorConstructor$14.construct(ConstructorConstructor.java:228)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:212)
at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.read(TypeAdapterRuntimeTypeWrapper.java:41)
at com.google.gson.internal.bind.MapTypeAdapterFactory$Adapter.read(MapTypeAdapterFactory.java:186)
at com.google.gson.internal.bind.MapTypeAdapterFactory$Adapter.read(MapTypeAdapterFactory.java:145)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:131)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:222)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:131)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:222)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:131)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:222)
at com.google.gson.Gson.fromJson(Gson.java:932)
at com.google.gson.Gson.fromJson(Gson.java:897)
at com.google.gson.Gson.fromJson(Gson.java:846)
at com.myapp.ui.customGame.CustomGameViewModel.initialize(CustomGameViewModel.kt:46)
道:
package com.myapp.data
import androidx.room.*
@Dao
interface GameDao {
@Query("SELECT * FROM gameData_table")
suspend fun getAll(): List<GameData>
@Query("SELECT * FROM gameData_table WHERE id = (:id)")
fun loadAllByIds(id: Array<Int>): List<GameData>
@Query("SELECT * FROM gameData_table WHERE is_over = 0")
suspend fun getOngoing() : List<GameData>
@Insert(onConflict = OnConflictStrategy.REPLACE)
suspend fun insertAll(vararg game: GameData)
@Delete
suspend fun delete(game: GameData)
@Query("DELETE FROM gameData_table WHERE is_over = 0")
suspend fun deleteOngoing()
@Query("UPDATE gameData_table SET game_json = (:json) WHERE gid = (:gameId)")
suspend fun updateJSON(json: String, gameId : String)
}
存储库:
package com.myapp.data
import kotlinx.coroutines.runBlocking
class GameRepository (private val gameDao: GameDao){
val allGameData: List<GameData> = runBlocking { gameDao.getAll()}
val ongoingGameData : List<GameData> = runBlocking { gameDao.getOngoing() }
suspend fun insert(gameData : GameData){
gameDao.insertAll(gameData)
}
suspend fun deleteOngoing() {
gameDao.deleteOngoing()
}
suspend fun updateGame(gameData : GameData){
gameDao.updateJSON(gameData.gameJson!!, gameData.gid!!)
}
}
package com.myapp.data
导入kotlinx.coroutines.runBlocking
类GameRepository(私有val gameDao:gameDao){
val allGameData:List=runBlocking{gameDao.getAll()}
val-ongoingGameData:List=runBlocking{gameDao.getContinuous()}
暂停趣味插入(gameData:gameData){
gameDao.insertAll(gameData)
}
暂停(正在进行的){
gameDao.deleteDao()
}
暂停趣味更新游戏(gameData:gameData){
gameDao.updateJSON(gameData.gameJson!!,gameData.gid!!)
}
}
b) 游戏课
现在是一个非常简短的游戏版本,因为大多数方法都与我的问题无关,我认为:
package com.myapp.game
import android.app.Application
import androidx.lifecycle.LiveData
import androidx.lifecycle.MutableLiveData
import com.myapp.data.GameData
import com.myapp.values.Values
import com.google.gson.Gson
class Game {
/*
No live data needed or possible?
*/
private var sets : MutableList<Set>
private val pointGap : Int = Values.DEFAULT_POINT_GAP
private val gid : String = this.toString()
/*
Live data needed or possible
*/
// private MutableLiveData
private var _team1Name : MutableLiveData<String> = MutableLiveData(Values.DEFAULT_TEAM1_NAME)
(more strings ...)
private var _setWinScore : MutableLiveData<Int> = MutableLiveData(Values.DEFAULT_WIN_SCORE)
(...)
// public LiveData
val team1Name : LiveData<String>
(more strings ...)
val setWinScore : LiveData<Int>
(...)
init{
team1Name = _team1Name
(more strings ...)
setWinScore = _setWinScore
(...)
}
constructor(gameSettings: GameSettings = GameSettings()){
this._team1Name.value = gameSettings.team1Name
(more strings...)
this._setWinScore.value = gameSettings.setWinScore
(...)
}
}
package com.myapp.game
导入android.app.Application
导入androidx.lifecycle.LiveData
导入androidx.lifecycle.MutableLiveData
导入com.myapp.data.GameData
导入com.myapp.values.values
导入com.google.gson.gson
班级游戏{
/*
不需要或可能没有实时数据?
*/
私有变量集:可变列表
private val pointGap:Int=Values.DEFAULT_POINT_GAP
private val gid:String=this.toString()
/*
需要或可能需要实时数据
*/
//私有可变LiveData
私有var\u team1Name:MutableLiveData=MutableLiveData(value.DEFAULT\u TEAM1\u NAME)
(更多字符串…)
私有变量_setWinScore:MutableLiveData=MutableLiveData(value.DEFAULT_WIN_SCORE)
(...)
//公共实时数据
val team1Name:LiveData
(更多字符串…)
val setWinScore:LiveData
(...)
初始化{
团队名称=_团队名称
(更多字符串…)
setWinScore=_setWinScore
(...)
}
构造函数(gameSettings:gameSettings=gameSettings()){
这是。_team1Name.value=gameSettings.team1Name
(更多字符串…)
这是。_setWinScore.value=gameSettings.setWinScore
(...)
}
}
3.解决方法#
我试着使用InstanceCreator。但是在我读了一些关于它的内容之后,我发现如果您想要重新创建的对象有一个Gson类需要知道的参数,那么这是必要的(例如,上下文)。我想我没有这个(?。我试过了,当然没用。 我还尝试了使用TypeToken的几种变体,我在开始时也展示了这些变体 我经常读到的另一件事是使用最新版本的包Gson、Room和LiveData,或者在项目级的grandle.build中使用kapt instad of implement关键字。 我尝试了两个->相同的异常 那么,你有什么想法吗? 还是我做错了什么愚蠢的事?
提前感谢您牺牲您的时间
PS:我不是英语母语,很抱歉语法和拼写不好。下面展示了如何反序列化
LiveData
,但是在您的用例中,可能更适合将游戏
数据作为视图模型
共享?看
当没有自定义或内置类型适配器匹配时,Gson使用基于反射的适配器。问题在于,您要求Gson将JSON反序列化为
LiveData
。如果查看LiveData
的字段,您将看到它有多个私有字段,对于其中一个字段的类型,Gson无法创建实例
一般来说,不鼓励对任何第三方类(此处为LiveData
)使用Gson基于反射的序列化或反序列化,因为这样您就依赖于它们的内部实现细节,这些细节可能会在任何时候发生变化
这可以通过创建自定义项来解决。我不熟悉Kotlin,但希望以下Java代码对您有用,尽管如此:
类LiveDataTypeAdapterFactory实现TypeAdapterFactory{
公共静态最终LiveDataTypeAdapterFactory实例=新的LiveDataTypeAdapterFactory();
私有LiveDataTypeAdapterFactory(){}
@凌驾
公共类型适配器创建(Gson Gson,TypeToken类型){
类rawType=type.getRawType();
//仅处理LiveData和MutableLiveData
if(rawType!=LiveData.class&&rawType!=MutableLiveData.class){
返回null;
}
//假设LiveData从未用作原始类型,但始终是参数化的
类型valueType=((ParameteredType)类型.getType()).getActualTypeArguments()[0];
//获取LiveData值类型`T的适配器`
//转换TypeAdapter以简化下面的适配器代码
@抑制警告(“未选中”)
TypeAdapter valueAdapter=(TypeAdapter)gson.getAdapter(TypeToken.get(valueType));
//由于在方法开始时进行“type”检查,因此是安全的
@抑制警告(“未选中”)
TypeAdapter=(TypeAdapter)新的TypeAdapter读取(JsonReader in)引发IOException{
对象值=valueAdapter.read(在中);
返回新的可变LiveData(值);
}
};
返回适配器;
}
}
(请注意,这不会保留LiveData
的观察者)
然后,您可以使用创建Gson
实例并注册工厂:
Gson Gson=new GsonBuilder()
.registerTypeAdapterFactory(LiveDataTypeAdapterFactory.INSTANCE)
.create();
反序列化游戏
时不需要使用TypeToken
,直接使用类也可以<代码>类型标记用于泛型类型
理想情况下,您还可以创建一个TypeAdapterFactorypackage com.myapp.data
import android.content.Context
import androidx.room.Database
import androidx.room.Room
import androidx.room.RoomDatabase
@Database(entities = [GameData::class], version = 1, exportSchema = false)
abstract class GameDatabase : RoomDatabase() {
abstract fun gameDao() : GameDao
companion object {
//Singleton pattern to prevent multiple instances of the database
@Volatile
private var INSTANCE: GameDatabase? = null
fun getDatabase(context: Context) : GameDatabase {
return INSTANCE ?: synchronized(this){
val instance = Room.databaseBuilder(
context.applicationContext,
GameDatabase::class.java,
"game_database"
).build()
INSTANCE = instance
return instance
}
}
}
package com.myapp.data
import kotlinx.coroutines.runBlocking
class GameRepository (private val gameDao: GameDao){
val allGameData: List<GameData> = runBlocking { gameDao.getAll()}
val ongoingGameData : List<GameData> = runBlocking { gameDao.getOngoing() }
suspend fun insert(gameData : GameData){
gameDao.insertAll(gameData)
}
suspend fun deleteOngoing() {
gameDao.deleteOngoing()
}
suspend fun updateGame(gameData : GameData){
gameDao.updateJSON(gameData.gameJson!!, gameData.gid!!)
}
}
package com.myapp.game
import android.app.Application
import androidx.lifecycle.LiveData
import androidx.lifecycle.MutableLiveData
import com.myapp.data.GameData
import com.myapp.values.Values
import com.google.gson.Gson
class Game {
/*
No live data needed or possible?
*/
private var sets : MutableList<Set>
private val pointGap : Int = Values.DEFAULT_POINT_GAP
private val gid : String = this.toString()
/*
Live data needed or possible
*/
// private MutableLiveData
private var _team1Name : MutableLiveData<String> = MutableLiveData(Values.DEFAULT_TEAM1_NAME)
(more strings ...)
private var _setWinScore : MutableLiveData<Int> = MutableLiveData(Values.DEFAULT_WIN_SCORE)
(...)
// public LiveData
val team1Name : LiveData<String>
(more strings ...)
val setWinScore : LiveData<Int>
(...)
init{
team1Name = _team1Name
(more strings ...)
setWinScore = _setWinScore
(...)
}
constructor(gameSettings: GameSettings = GameSettings()){
this._team1Name.value = gameSettings.team1Name
(more strings...)
this._setWinScore.value = gameSettings.setWinScore
(...)
}
}