英文:
com.google.firebase.database.DatabaseException: Can't convert object of type java.lang.String to type com.NoteModelActivity error arising suddenly
问题
I see you're encountering an issue with Firebase database conversion in your Android app. The error message you're getting is:
com.google.firebase.database.DatabaseException: Can't convert object of type java.lang.String to type com.NoteModelActivity
This error occurs because Firebase is trying to convert a string from the database to an instance of NoteModelActivity, but it's unable to do so because there's a mismatch between the data in the database and the expected class structure.
To resolve this issue, you should check the data in your Firebase database to ensure it matches the structure of your NoteModelActivity class. Specifically, make sure that the data under the path you're querying with fNotesDatabase has fields named noteTitle and noteTime. If these fields are missing or have a different data type, you'll encounter this error.
Also, it's important to ensure that the database structure hasn't changed unexpectedly, causing this issue.
Additionally, make sure that you're using the correct field names when retrieving data from the database. In your onBindViewHolder method, you are checking for fields named "title" and "timestamp," but in your NoteModelActivity class, you have "noteTitle" and "noteTime." Ensure that these field names match.
If you have verified that your database structure and data are correct, and you're still encountering the issue, please provide more information about your database structure and how data is stored under the fNotesDatabase path so that I can offer more specific guidance.
As for the second error about the "postsRecyclerView" class, it seems unrelated to the code you've posted here. If you encounter issues with that class, you may need to review the code and database structure related to it separately.
英文:
My app was working absolutely fine but then suddenly out of the blue i get this error:
com.google.firebase.database.DatabaseException: Can't convert object of type java.lang.String to type com.NoteModelActivity
Im using a recyclerView.
and I'm unable to understand from where did this issue arise all of a sudden in a working app.
as soon as i open the activity the app crashes. whereas before without any change it worked perfectly fine.
I read solutions to this question but the answers were related to 'toString' in Value listener but i have already implemented that..
please help me..
My logcat:
com.google.firebase.database.DatabaseException: Can't convert object of type java.lang.String to type com.NoteModelActivity
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.convertBean(CustomClassMapper.java:435)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.deserializeToClass(CustomClassMapper.java:231)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.convertToCustomClass(CustomClassMapper.java:79)
at com.google.firebase.database.DataSnapshot.getValue(DataSnapshot.java:203)
at com.firebase.ui.database.ClassSnapshotParser.parseSnapshot(ClassSnapshotParser.java:29)
at com.firebase.ui.database.ClassSnapshotParser.parseSnapshot(ClassSnapshotParser.java:15)
at com.firebase.ui.common.BaseCachingSnapshotParser.parseSnapshot(BaseCachingSnapshotParser.java:36)
at com.firebase.ui.common.BaseObservableSnapshotArray.get(BaseObservableSnapshotArray.java:52)
at com.firebase.ui.database.FirebaseRecyclerAdapter.getItem(FirebaseRecyclerAdapter.java:109)
at com.firebase.ui.database.FirebaseRecyclerAdapter.onBindViewHolder(FirebaseRecyclerAdapter.java:149)
at androidx.recyclerview.widget.RecyclerView$Adapter.onBindViewHolder(RecyclerView.java:7065)
at androidx.recyclerview.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:7107)
at androidx.recyclerview.widget.RecyclerView$Recycler.tryBindViewHolderByDeadline(RecyclerView.java:6012)
at androidx.recyclerview.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:6279)
at androidx.recyclerview.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:6118)
at androidx.recyclerview.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:6114)
at androidx.recyclerview.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2303)
at androidx.recyclerview.widget.GridLayoutManager.layoutChunk(GridLayoutManager.java:561)
at androidx.recyclerview.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1587)
at androidx.recyclerview.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:665)
at androidx.recyclerview.widget.GridLayoutManager.onLayoutChildren(GridLayoutManager.java:170)
at androidx.recyclerview.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:4134)
at androidx.recyclerview.widget.RecyclerView.dispatchLayout(RecyclerView.java:3851)
at androidx.recyclerview.widget.RecyclerView.consumePendingUpdateOperations(RecyclerView.java:1897)
at androidx.recyclerview.widget.RecyclerView$1.run(RecyclerView.java:414)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:1147)
at android.view.Choreographer.doCallbacks(Choreographer.java:958)
at android.view.Choreographer.doFrame(Choreographer.java:881)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:1133)
at android.os.Handler.handleCallback(Handler.java:873)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:226)
at android.app.ActivityThread.main(ActivityThread.java:7224)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:500)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:913)
My model class:
public class NoteModelActivity {
public String noteTitle;
public String noteTime;
public NoteModelActivity() {
}
public NoteModelActivity(String noteTitle, String noteTime) {
this.noteTitle = noteTitle;
this.noteTime = noteTime;
}
public String getNoteTitle() {
return noteTitle;
}
public void setNoteTitle(String noteTitle) {
this.noteTitle = noteTitle;
}
public String getNoteTime() {
return noteTime;
}
public void setNoteTime(String noteTime) {
this.noteTime = noteTime;
}
My Activity:
fAuth = FirebaseAuth.getInstance();
if (fAuth.getCurrentUser() != null) {
fNotesDatabase = FirebaseDatabase.getInstance().getReference().child("Notes").child(fAuth.getCurrentUser().getUid());
}
loadData();
}
private void loadData() {
FirebaseRecyclerOptions<NoteModelActivity> options =
new FirebaseRecyclerOptions.Builder<NoteModelActivity>()
.setQuery(fNotesDatabase , NoteModelActivity.class)
.build();
FirebaseRecyclerAdapter<NoteModelActivity, NoteViewHolderActivity>
firebaseRecyclerAdapter = new FirebaseRecyclerAdapter<NoteModelActivity, NoteViewHolderActivity>(options) {
@NonNull
@Override
public NoteViewHolderActivity onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.single_note_layout, parent, false);
NoteViewHolderActivity viewHolder = new NoteViewHolderActivity(view);
return viewHolder;
}
@Override
protected void onBindViewHolder(@NonNull final NoteViewHolderActivity holder, int position, @NonNull NoteModelActivity model) {
final String noteId = getRef(position).getKey();
fNotesDatabase.child(noteId).addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
if (dataSnapshot.hasChild("title") && dataSnapshot.hasChild("timestamp")) {
String title = dataSnapshot.child("title").getValue(String.class);
String timestamp = dataSnapshot.child("timestamp").getValue(String.class);
holder.setNoteTitle(title);
GetTimeAgo getTimeAgo = new GetTimeAgo();
holder.setNoteTime(getTimeAgo.getTimeAgo(Long.parseLong(timestamp), getApplicationContext()));
holder.noteCard.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent intent = new Intent(PostActivity.this, NewNoteActivity.class);
intent.putExtra("noteId", noteId);
startActivity(intent);
}
});
}
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
};
mNotesList.setAdapter(firebaseRecyclerAdapter);
firebaseRecyclerAdapter.startListening();
}
Now its showing another error about other activity which is a model for another recyclerview activity these two arent even related and yet the above activity is the one which crashes..
Class com..postsRecyclerView does not define a no-argument constructor. If you are using ProGuard, make sure these constructors are not stripped.
another model class;
public class postsRecyclerView {
public postsRecyclerView(String username, String article, String title, String date, String timestamp) {
this.username = username;
this.article = article;
this.title = title;
this.date = date;
this.timestamp = timestamp;
}
public String username, title,article, date, timestamp;
public String getTimestamp() {
return timestamp;
}
public void setTimestamp(String timestamp) {
this.timestamp = timestamp;
}
public String getDate() {
return date;
}
public void setDate(String date) {
this.date = date;
}
public String getArticle() {
return article;
}
public void setArticle(String article) {
this.article = article;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
}
My firebase database:
I would really appreciate your help...
please help me...
答案1
得分: 0
为您的postRecyclerview类添加一个无参数的构造函数，这将解决“不定义无参数构造函数”的问题。点击ctrl+alt+insert，然后点击构造函数，再点击选择none。对于您的第一个错误，似乎您的数据库中有一个字符串，并且检索方法不起作用。您能上传一个数据库的图像，以便我可以找出您的问题。
英文:
For your postRecyclerview class add a constructor with no parameter, this will solve the
'does not define a no-argument constructor'. Click on ctrl+alt+insert, and click on constructor and click on select none.For your first error it seems you have a string in database and the retrieving method is not working. Can you upload an image of your database so that i could dig up your problem.
通过集体智慧和协作来改善编程学习和解决问题的方式。致力于成为全球开发者共同参与的知识库，让每个人都能够通过互相帮助和分享经验来进步。
评论