我尝试搜索该特定条目，但我得到了一个错误。重要的是要注意，RecylerView的代码是正确的，确实只在搜索中显示元素。我得到了一个错误，我不知道在哪里：
recyclerView= findViewById(R.id.recycleview);
getmRootFLY = FirebaseDatabase.getInstance().getReference("FLY");
list = new ArrayList<>();
arrayList = new ArrayList<>();
recyclerView.setLayoutManager(new LinearLayoutManager(this));
myAdapter = new MyAdapter(this,list);
recyclerView.setAdapter(myAdapter);
getmRootFLY.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot snapshot) {
for (DataSnapshot dataSnapshot: snapshot.getChildren())
{
Fly fly = dataSnapshot.getValue(Fly.class);
list.add(fly);
}
myAdapter.notifyDataSetChanged();
}
@Override
public void onCancelled(@NonNull DatabaseError error) {
}
});
\\search func.................................
DatabaseReference ref = FirebaseDatabase.getInstance().getReference().child("FLY").child("-NJzbEcGdb8_fvLxWFJk");
ref.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot)
{
list.clear();
for (DataSnapshot dataSnapshot1: dataSnapshot.getChildren())
{
Fly fly = dataSnapshot1.getValue(Fly.class);
list.add(fly);
}
myAdapter.notifyDataSetChanged();
}
@Override
public void onCancelled(@NonNull DatabaseError error) {
}
});
}
});
}
}
//worng in console..............................
com.google.firebase.database.DatabaseException: Can't convert object of type java.lang.String to type com.example.newp.Fly
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.convertBean(CustomClassMapper.java:436)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.deserializeToClass(CustomClassMapper.java:232)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.convertToCustomClass(CustomClassMapper.java:80)
at com.google.firebase.database.DataSnapshot.getValue(DataSnapshot.java:203)
at com.example.newp.MainActivity$4$1.onDataChange(MainActivity.java:150)
at com.google.firebase.database.core.ValueEventRegistration.fireEvent(ValueEventRegistration.java:75)
at com.google.firebase.database.core.view.DataEvent.fire(DataEvent.java:63)
at com.google.firebase.database.core.view.EventRaiser$1.run(EventRaiser.java:55)
at android.os.Handler.handleCallback(Handler.java:942)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loopOnce(Looper.java:201)
at android.os.Looper.loop(Looper.java:288)
at android.app.ActivityThread.main(ActivityThread.java:7872)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:548)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:936)
1条答案
按热度按时间8gsdolmq1#
您将收到以下错误：
com.google.firebase.database.DatabaseException:无法将java.lang.String类型的对象转换为com.example.newp.Fly类型
因为当你创建一个指向
db/FLY/-NJzbEcGdb8_fvLxWFJk的引用并循环遍历结果时，你得到的不是Fly对象，而是字符串，所以会出现错误。如果你想得到FLY节点下存在的所有对象并将它们添加到一个列表中，那么你必须删除对.child("-NJzbEcGdb8_fvLxWFJk")的调用。所以你的引用应该如下所示：