[英]DataSnapshot cannot be cast to Adapter
我有一個問題,我正在為 RecyclerView 創建一個適配器,為了創建它,我使用 FirebaseRecyclerAdapter 擴展了類,但是我收到一個錯誤,我不知道如何解決它,也許有人可以告訴我一些事情。 我在網上找到了一個類似的例子,可以用這種方式擴展一個類,但要么是我做錯了什么,要么就不能再用這種方式擴展類了。 非常感謝您的幫助
這是我的適配器:
public class PostAdapterTest extends FirebaseRecyclerAdapter <Posts, PostAdapterTest.postsViewHolder> { //error the error is here
private BottomSheetDialog bottomSheetDialog;
private Context mContext;
private Boolean downloadOrOpen = false;
private boolean buttonStatus = true;
private DatabaseReference likesRef = FirebaseDatabase.getInstance().getReference("Likes");
private FirebaseUser mFirebaseUser = FirebaseAuth.getInstance().getCurrentUser();
private String difficulty = null;
private int likesCounter;
private ReadWritePermissions mReadWritePermissions;
public PostAdapterTest(@NonNull FirebaseRecyclerOptions<Posts> postsFirebaseRecyclerOptions, ReadWritePermissions mReadWritePermissions, Context mContext)
{
super(postsFirebaseRecyclerOptions);
this.mContext = mContext;
this.mReadWritePermissions = mReadWritePermissions;
}
@Override
protected void onBindViewHolder(@NonNull PostAdapterTest.postsViewHolder holder, int position, @NonNull Posts model) {
final String postKey = getRef(position).getKey();
String postUid = model.getPostId();
holder.nickname.setText(model.getNickname());
holder.country.setText(model.getCountry());
holder.title.setText(model.getCountry());
holder.days.setText(model.getDays());
holder.kilometers.setText(model.getKilometers());
holder.description.setText(model.getDescription());
difficulty = model.getDifficulty();
holder.map.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Uri mapUri = Uri.parse(model.getMap());
mapOptions(mapUri);
}
});
holder.comments.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
CommentsFragment commentsFragment = new CommentsFragment();
Bundle args = new Bundle();
args.putString("postId", postUid);
commentsFragment.setArguments(args);
FragmentTransaction fragmentTransaction = ((FragmentActivity)mContext).getSupportFragmentManager().beginTransaction();
fragmentTransaction.replace(R.id.frame_container, commentsFragment);
fragmentTransaction.addToBackStack(null);
fragmentTransaction.commit();
}
});
holder.setLikeButtonStatus(postKey);
holder.likes.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
buttonStatus = true;
likesRef.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot snapshot) {
if(buttonStatus == true)
{
if(snapshot.child(postKey).hasChild(mFirebaseUser.getUid()))
{
likesRef.child(postKey).child(mFirebaseUser.getUid()).removeValue();
buttonStatus = false;
}else
{
likesRef.child(postKey).child(mFirebaseUser.getUid()).setValue(true);
buttonStatus = false;
}
}
}
@Override
public void onCancelled(@NonNull DatabaseError error) {
}
});
switch (difficulty)
{
case "Easy":
holder.difficulty.setImageResource(R.drawable.ic_easy);
break;
case "Difficult":
holder.difficulty.setImageResource(R.drawable.ic_difficult);
break;
case "Hard":
holder.difficulty.setImageResource(R.drawable.ic_hard);
break;
}
ArrayList<Slider> sliderArrayList = new ArrayList<>();
Picasso.get().load(model.getAvatarUri()).into(holder.avatarUri);
}
});
}
@NonNull
@Override
public PostAdapterTest.postsViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext())
.inflate(R.layout.posts, parent, false);
return new PostAdapterTest.postsViewHolder(view);
}
class postsViewHolder extends RecyclerView.ViewHolder
{
public CircleImageView avatarUri;
public TextView nickname, country, title, days, likesNum, kilometers,description, fileSize, fileName;
public SliderView mSliderView;
public ImageView comments, save, difficulty;
public ImageButton likes;
public ImageButton more;
public LinearLayout map;
public postsViewHolder(@NonNull View itemView) {
super(itemView);
avatarUri = itemView.findViewById(R.id.posts_profile_picture);
nickname = itemView.findViewById(R.id.posts_nickname);
country = itemView.findViewById(R.id.posts_country);
title = itemView.findViewById(R.id.posts_title);
days = itemView.findViewById(R.id.posts_days);
difficulty = itemView.findViewById(R.id.posts_difficulty);
mSliderView = itemView.findViewById(R.id.posts_images);
likes = itemView.findViewById(R.id.posts_likes);
comments = itemView.findViewById(R.id.posts_comments);
save = itemView.findViewById(R.id.posts_save);
likesNum = itemView.findViewById(R.id.posts_likes_number);
description = itemView.findViewById(R.id.posts_description);
more = itemView.findViewById(R.id.posts_more);
kilometers = itemView.findViewById(R.id.posts_distance);
fileSize = itemView.findViewById(R.id.posts_uploaded_file_size);
fileName = itemView.findViewById(R.id.posts_uploaded_file_name);
map = itemView.findViewById(R.id.posts_map_layout);
}
public void setLikeButtonStatus(final String key)
{
mFirebaseUser = FirebaseAuth.getInstance().getCurrentUser();
likesRef.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot snapshot) {
likesCounter = (int)snapshot.child(key).getChildrenCount();
if(snapshot.child(key).hasChild(mFirebaseUser.getUid()))
{
likes.setImageResource(R.drawable.ic_liked_red);
likesNum.setText(likesCounter + " Likes");
}else if(likesCounter == 0)
{
likes.setImageResource(R.drawable.ic_unliked_red);
likesNum.setText("");
}else
{
likes.setImageResource(R.drawable.ic_unliked_red);
likesNum.setText(likesCounter + " Likes");
}
}
@Override
public void onCancelled(@NonNull DatabaseError error) {
}
});
}
}
private void mapOptions(Uri mapUri)
{
}
}
日志貓:
Process: com.company.android.myapplication, PID: 8349
java.lang.ClassCastException: com.google.firebase.database.DataSnapshot cannot be cast to com.company.android.myapplication.Posts
at com.company.android.myapplication.test.PostAdapterTest.onBindViewHolder(PostAdapterTest.java:44)
at com.firebase.ui.database.FirebaseRecyclerAdapter.onBindViewHolder(FirebaseRecyclerAdapter.java:149)
at androidx.recyclerview.widget.RecyclerView$Adapter.onBindViewHolder(RecyclerView.java:7254)
at androidx.recyclerview.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:7337)
at androidx.recyclerview.widget.RecyclerView$Recycler.tryBindViewHolderByDeadline(RecyclerView.java:6194)
at androidx.recyclerview.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:6460)
at androidx.recyclerview.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:6300)
at androidx.recyclerview.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:6296)
at androidx.recyclerview.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2330)
at androidx.recyclerview.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1631)
at androidx.recyclerview.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1591)
at androidx.recyclerview.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:668)
at androidx.recyclerview.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:4309)
at androidx.recyclerview.widget.RecyclerView.dispatchLayout(RecyclerView.java:4012)
at androidx.recyclerview.widget.RecyclerView.onLayout(RecyclerView.java:4578)
java.lang.ClassCastException:com.google.firebase.database.DataSnapshot 無法轉換為 com.company.android.myapplication.Posts
您不能將DataSnapshot
為您自己的 pojo Posts
,您必須從DataSnapshot
獲取value
。 此外,請確保DataSnapshot
架構和您的 pojo Posts
架構正確匹配以將DataSnapshot
值解析為Posts
。
此外,直接從 Adapter 進行查詢或調用活動或進行 Firebase 事務是非常糟糕的方法。 您應該將回調傳遞給適配器並處理片段/活動的邏輯。
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