虽然这个问题已经回答了几次，但任何答案都无法解决我的问题。
我有一个firebase数据库，它只有两个键值对。以下是json。
{
"route" : {
"routeA" : {
"stop" : "Street 1",
"time" : "11:00 PM"
}
}
}
以下是我从firebase DB获取数据的代码
recyclerView = (RecyclerView) findViewById(R.id.recyclerView);
recyclerView.setHasFixedSize(true);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
rootRef = new Firebase("https://listrecycler.firebaseio.com/route/");
}
@Override
protected void onStart() {
super.onStart();
itemsRef = rootRef.child("route B");
Toast.makeText(MainActivity.this, "crossed itemRef", Toast.LENGTH_SHORT).show();
firebaseRecyclerAdapter = new FirebaseRecyclerAdapter<Route, RouteViewHolder>(Route.class, android.R.layout.two_line_list_item, RouteViewHolder.class, itemsRef) {
@Override
public void populateViewHolder(RouteViewHolder routeViewHolder, Route route, int i) {
Toast.makeText(MainActivity.this, "reached populate view holder", Toast.LENGTH_SHORT).show();
Log.d(TAG, "populateViewHolder: " + route);
routeViewHolder.place.setText(route.getStop());
routeViewHolder.time.setText(route.getTime());
}
};
recyclerView.setAdapter(firebaseRecyclerAdapter);
}
public static class RouteViewHolder extends RecyclerView.ViewHolder {
TextView place;
TextView time;
public RouteViewHolder(View itemView) {
super(itemView);
place = (TextView) itemView.findViewById(android.R.id.text1);
time = (TextView) itemView.findViewById(android.R.id.text2);
}
}
这是简单的代码，没有Frank建议的任何Recyclerview。代码工作正常。没有杰克逊的错误
rootRef = new Firebase("https://listrecycler.firebaseio.com/route");
}
@Override
protected void onStart() {
super.onStart();
itemsRef = rootRef.child("routeA");
itemsRef.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
Route routeDetails = dataSnapshot.getValue(Route.class);
String stop = routeDetails.getStop();
String time = routeDetails.getTime();
Toast.makeText(MainActivity.this, "Stop Name:"+ stop+"Time:"+time, Toast.LENGTH_SHORT).show();
Log.d(TAG, "onDataChange: "+dataSnapshot);
}
@Override
public void onCancelled(FirebaseError firebaseError) {
}
});
}
以下是我的POJO
public class Route {
public String stop;
public String time;
public Route() {
}
public Route(String stop, String time) {
this.stop = stop;
this.time = time;
}
public String getStop() {
return stop;
}
public void setStop(String stop) {
this.stop = stop;
}
public String getTime() {
return time;
}
public void setTime(String time) {
this.time = time;
}
}
代码的问题在于，当我使用POJO时，Jackson无法反序列化Firebase发送的数据。当我使用简单的String类而不是Route POJO时，数据被完美地写入回收器视图项。以下是错误日志
05-06 22:38:03.724 30051-30051/abc.com.example.vijsu.listrecyclerfirebase E/AndroidRuntime: FATAL EXCEPTION: main
Process: abc.com.example.vijsu.listrecyclerfirebase, PID: 30051
com.firebase.client.FirebaseException: Failed to bounce to type
at com.firebase.client.DataSnapshot.getValue(DataSnapshot.java:183)
at com.firebase.ui.FirebaseRecyclerAdapter.parseSnapshot(FirebaseRecyclerAdapter.java:161)
at com.firebase.ui.FirebaseRecyclerAdapter.getItem(FirebaseRecyclerAdapter.java:150)
at com.firebase.ui.FirebaseRecyclerAdapter.onBindViewHolder(FirebaseRecyclerAdapter.java:190)
at android.support.v7.widget.RecyclerView$Adapter.onBindViewHolder(RecyclerView.java:5465)
at android.support.v7.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:5498)
at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:4735)
at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:4611)
at android.support.v7.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:1988)
at android.support.v7.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1384)
at android.support.v7.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1347)
at android.support.v7.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:574)
at android.support.v7.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:3026)
at android.support.v7.widget.RecyclerView.dispatchLayout(RecyclerView.java:2903)
at android.support.v7.widget.RecyclerView.consumePendingUpdateOperations(RecyclerView.java:1457)
at android.support.v7.widget.RecyclerView.access$400(RecyclerView.java:147)
at android.support.v7.widget.RecyclerView$1.run(RecyclerView.java:285)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:858)
at android.view.Choreographer.doCallbacks(Choreographer.java:670)
at android.view.Choreographer.doFrame(Choreographer.java:603)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:844)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: com.fasterxml.jackson.databind.JsonMappingException: Can not instantiate value of type [simple type, class abc.com.example.vijsu.listrecyclerfirebase.Route] from String value; no single-String constructor/factory method
at com.fasterxml.jackson.databind.deser.std.StdValueInstantiator._createFromStringFallbacks(StdValueInstantiator.java:428)
at com.fasterxml.jackson.databind.deser.std.StdValueInstantiator.createFromString(StdValueInstantiator.java:299)
at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.deserializeFromString(BeanDeserializerBase.java:1056)
at com.fasterxml.jackson.databind.deser.BeanDeserializer._deserializeOther(BeanDeserializer.java:136)
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:123)
at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:2888)
at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2034)
at com.firebase.client.DataSnapshot.getValue(DataSnapshot.java:181)
at com.firebase.ui.FirebaseRecyclerAdapter.parseSnapshot(FirebaseRecyclerAdapter.java:161)
at com.firebase.ui.FirebaseRecyclerAdapter.getItem(FirebaseRecyclerAdapter.java:150)
at com.firebase.ui.FirebaseRecyclerAdapter.onBindViewHolder(FirebaseRecyclerAdapter.java:190)
at android.support.v7.widget.RecyclerView$Adapter.onBindViewHolder(RecyclerView.java:5465)
at android.support.v7.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:5498)
at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:4735)
at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:4611)
at android.support.v7.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:1988)
at android.support.v7.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1384)
at android.support.v7.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1347)
at android.support.v7.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:574)
at android.support.v7.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:3026)
at android.support.v7.widget.RecyclerView.dispatchLayout(RecyclerView.java:2903)
at android.support.v7.widget.RecyclerView.consumePendingUpdateOperations(RecyclerView.java:1457)
at android.support.v7.widget.RecyclerView.access$400(RecyclerView.java:147)
at android.support.v7.widget.RecyclerView$1.run(RecyclerView.java:285)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:858)
at android.view.Choreographer.doCallbacks(Choreographer.java:670)
at android.view.Choreographer.doFrame(Choreographer.java:603)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:844)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
我刷新了Firebase检查中的数据，以确保POJO和Firebase数据库中的String名称匹配多次。我理解我错过了与POJO有关但却无法解决的问题。
但是回收者视图仍然存在错误!!!
答案 0 :(得分：4)
错误提及此
无法实例化类型的值...路由...没有单字符串构造函数/工厂方法
所以你可能想要添加一个
public class Route {
public String stop;
public String time;
public Route() {}
public Route(String routeJSON) {
// TODO: Parse out JSON object
// call setters...
}
public Route(String stop, String time) {
this.stop = stop;
this.time = time;
}
答案 1 :(得分：0)
最愚蠢的错误是我忘记了一个回收者视图获取属性列表，并且我有多个属性（停止和时间）显示在一行中。所以我只需要获取 routeA 并将其提供给firebasui进行显示。我进入更深层次，同时将数据提升到routeA并且firebaseui无法识别属性。只有一个级别的查询到路径足以在单行中显示停止和时间属性。
把它写成一个单独的答案，这样可以帮助像我这样的人，他们对一些不重要的事情一无所知。这个概念也是@Frank van Puffelen发布给其中一个类似答案的答案的一部分。