RecyclerView未显示在我的MainActivity中的项目

Question

我正在构建一个具有帖子功能的聊天应用程序，当我在NewPostActivity中创建帖子时，图像和文本会被上传(因为我可以在firebase数据库树中看到它们(，但问题是我的MainActivity中没有显示任何内容，它应该显示我的帖子。

我在Rv中使用了Firebase UI，但我不确定问题出在NewPostActivity还是MainActivity。我试着运行调试器查看，但没有错误或null点异常。

NewPostActivity.java

btnPost.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
startPosting();
}
});

}
private void startPosting() {

progressDialog=new ProgressDialog(NewPostActivity.this);
progressDialog.setTitle("Uploading Image");
progressDialog.setMessage("Please Wait while we process the image");
progressDialog.setCanceledOnTouchOutside(false);

final String desc_val=mPostDesc.getText().toString().trim();

if(!TextUtils.isEmpty(desc_val) && mImageUri!=null){
progressDialog.show();
String random_name= random();
StorageReference filepath = storageReference.child("Blog_Images").child(random_name);
filepath.putFile(mImageUri).addOnCompleteListener(new OnCompleteListener<UploadTask.TaskSnapshot>() {
@Override
public void onComplete(@NonNull Task<UploadTask.TaskSnapshot> task) {
Task<Uri> uriTask = task.getResult().getStorage().getDownloadUrl();
while (!uriTask.isComplete());
final Uri downloadUrl = uriTask.getResult();
final DatabaseReference newPost = mRootRef.child("Blog").push();
final String user_id= mCurrentUser.getUid();
mRootRef.child("Users").child(user_id).addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
newPost.child("desc").setValue(desc_val);
newPost.child("image").setValue(downloadUrl.toString());
newPost.child("user_id").setValue(user_id);
newPost.child("timestamp").setValue(ServerValue.TIMESTAMP);
newPost.child("username").setValue(dataSnapshot.child("name").getValue());
newPost.child("thumb_image").setValue(dataSnapshot.child("thumb_image").getValue());
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
progressDialog.dismiss();
startActivity(new Intent(NewPostActivity.this,MainActivity.class));
finish();
}
});

}
}

MainActivity.java

Query conversationQuery = mDatabase.orderByChild("timestamp");
FirebaseRecyclerOptions<Blog> options = new FirebaseRecyclerOptions.Builder<Blog>()
.setQuery(conversationQuery, Blog.class)
.build();
FirebaseRecyclerAdapter<Blog, BlogViewHolder> firebaseRecyclerAdapter = new FirebaseRecyclerAdapter<Blog, BlogViewHolder>(options) {
@NonNull
@Override
public BlogViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext())
.inflate(R.layout.post_single_layout, parent, false);
mAuth = FirebaseAuth.getInstance();
return new BlogViewHolder(view);
}
@Override
protected void onBindViewHolder(@NonNull final BlogViewHolder viewHolder, int position, @NonNull final Blog model) {
viewHolder.setContext(getApplicationContext());
final String list_blog_id = getRef(position).getKey();
viewHolder.setLikeBtns(list_blog_id);
Query lastMessageQuery = mDatabase.child(list_blog_id).limitToLast(1);
lastMessageQuery.addChildEventListener(new ChildEventListener() {
@Override
public void onChildAdded(DataSnapshot dataSnapshot, String s) {
viewHolder.setDesc(model.getDesc());
viewHolder.setImage(model.getImage());
viewHolder.setUsername(model.getUsername());
viewHolder.setStatus(model.getStatus());
viewHolder.setPostImage(model.getThumb_image());
viewHolder.setTime(model.getTimestamp());
userID = model.getUid();
}
@Override
public void onChildChanged(DataSnapshot dataSnapshot, String s) {
}
@Override
public void onChildRemoved(DataSnapshot dataSnapshot) {
}
@Override
public void onChildMoved(DataSnapshot dataSnapshot, String s) {
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
viewHolder.postImage.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent imageFullScreen = new Intent(getApplicationContext(), PhotoActivity.class);
imageFullScreen.putExtra("uid", list_blog_id);
imageFullScreen.putExtra("from", "RequestsFragment");
startActivity(imageFullScreen);
}
});
viewHolder.mLikeBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
mProcessLike = true;
mDatabase.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
if (mProcessLike) {
if (dataSnapshot.child(list_blog_id).hasChild(mAuth.getCurrentUser().getUid())) {
mDatabaseLike.child(list_blog_id).child(mAuth.getCurrentUser().getUid()).removeValue();
mProcessLike = false;
} else {
mDatabaseLike.child(list_blog_id).child(mAuth.getCurrentUser().getUid()).setValue("Lliked");
mProcessLike = false;
}
}
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
});
}
};
mBlogList.setAdapter(firebaseRecyclerAdapter);
}

Answer 1

您的代码中有一些部分没有显示，也因为我没有看到您数据库的屏幕截图，我不知道我是否会给出正确的答案，但很明显，在使用firebase UI获取数据之前，您需要开始听数据库。

因此在此之前：

mBlogList.setAdapter(firebaseRecyclerAdapter);

添加此：

firebaseRecyclerAdapter.startListening();

请参阅此了解有关如何设置firebase UI的更多信息。