Question

我的应用程序运行正常，但是突然出现错误：

 com.google.firebase.database.DatabaseException: Can't convert object of type java.lang.String to type com.NoteModelActivity

我正在使用recyclerView。而且我无法理解在正常工作的应用中突然从何处出现此问题。一旦我打开活动，应用程序就会崩溃。而在没有任何更改的情况下，它运行得很好。

我阅读了此问题的解决方案，但答案与Value侦听器中的“ toString”有关，但我已经实现了。.

请帮助我。

我的日志猫：

      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)

我的模型班：

      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;
}

我的活动：

    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();
}

现在，它显示了另一个活动的另一个错误，这是另一个recyclerview活动的模型，这两个arent甚至相关，而上述活动是崩溃的。.

        Class com..postsRecyclerView does not define a no-argument constructor. If you are using ProGuard, make sure these constructors are not stripped.

另一个模型类；

  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;
}

}

我的Firebase数据库：

enter image description here

非常感谢您的帮助... 请帮助我...

Answer 1

为您的postRecyclerview类添加一个不带参数的构造函数，这将解决 “未定义无参数构造函数”。单击ctrl + alt + insert，然后单击构造函数，然后单击不选择。对于第一个错误，您似乎在数据库中有一个字符串，并且检索方法无效。您可以上传数据库的图片，以便我解决您的问题。

com.google.firebase.database.DatabaseException：无法将java.lang.String类型的对象转换为com.NoteModelActivity类型错误

1 个答案: