火力基地错误："Expected a List while deserializing, but got a class java.util.HashMap"

Question

我的数据库中有一个结构工作得很好，但后来我将以下节点添加到数据库中，从那以后我就收到了这个错误。如果我删除"commentList"节点，它将再次工作。为什么它会从列表变为哈希映射？

我的数据库结构。它在添加"commentList"之前起了作用

对此负责的代码：代码

这里的日志错误：

com.google.firebase.database.DatabaseException: Expected a List while deserializing, but got a class java.util.HashMap
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.deserializeToParameterizedType(com.google.firebase:firebase-database@@16.0.5:233)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.deserializeToType(com.google.firebase:firebase-database@@16.0.5:176)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.access$100(com.google.firebase:firebase-database@@16.0.5:47)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper$BeanMapper.deserialize(com.google.firebase:firebase-database@@16.0.5:580)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper$BeanMapper.deserialize(com.google.firebase:firebase-database@@16.0.5:550)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.convertBean(com.google.firebase:firebase-database@@16.0.5:420)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.deserializeToClass(com.google.firebase:firebase-database@@16.0.5:214)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.deserializeToType(com.google.firebase:firebase-database@@16.0.5:178)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.access$100(com.google.firebase:firebase-database@@16.0.5:47)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper$BeanMapper.deserialize(com.google.firebase:firebase-database@@16.0.5:580)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper$BeanMapper.deserialize(com.google.firebase:firebase-database@@16.0.5:550)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.convertBean(com.google.firebase:firebase-database@@16.0.5:420)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.deserializeToClass(com.google.firebase:firebase-database@@16.0.5:214)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.deserializeToType(com.google.firebase:firebase-database@@16.0.5:178)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.deserializeToParameterizedType(com.google.firebase:firebase-database@@16.0.5:247)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.deserializeToType(com.google.firebase:firebase-database@@16.0.5:176)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.convertToCustomClass(com.google.firebase:firebase-database@@16.0.5:101)
at com.google.firebase.database.DataSnapshot.getValue(com.google.firebase:firebase-database@@16.0.5:239)
at com.example.xandi.whib.MainActivity$3.onDataChange(MainActivity.java:236)
at com.google.firebase.database.core.ValueEventRegistration.fireEvent(com.google.firebase:firebase-database@@16.0.5:75)
at com.google.firebase.database.core.view.DataEvent.fire(com.google.firebase:firebase-database@@16.0.5:63)
at com.google.firebase.database.core.view.EventRaiser$1.run(com.google.firebase:firebase-database@@16.0.5:55)
at android.os.Handler.handleCallback(Handler.java:790)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6626)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:811)

是什么原因造成的？我该如何解决？

Answer 1

我知道有点晚了，但我会为遇到同样问题的其他人发布它。Firebase实时数据库不将集合存储在列表中，而是HashMaps。你的模型属性应该更像这样：

var commentList: HashMap<String, String>? = null

Answer 2

您必须确保firebase对象是数组，而不是映射，如下所示：火球

我也遇到过同样的问题，解决方案是直接在firebase数据库中检查对象的类型，并将Map(HashMap)更改为Array(List)