[英]How to retrieve data with RecycleView / firebase
我的firebase數據庫如下所示：
Firebase JSON：
我需要在recycleview卡視圖中顯示這些數據：帶有相關名稱的日期。
我的問題是：如何在Java類中實現這一點。 目前我是這樣的：
我知道，這些名稱應類似於Firebase中的名稱，但我需要使用getKey和getValue來完成。
public class UserParties {
public String createAccTime, uuid, party;
public UserParties() {
}
public UserParties(String party, String createAccTime) {
this.party = party;
this.createAccTime = createAccTime;
}
public String getParty() {
return party;
}
public void setParty(String party) {
this.party = party;
}
public String getCreateAccTime() {
return createAccTime;
}
public void setCreateAccTime(String createAccTime) {
this.createAccTime = createAccTime;
}
}
主要活動是：
public class AllUserPartiesListActivity extends AppCompatActivity {
private static final String TAG = "AllUserPartiesListActivity";
private RecyclerView UserPartiesList;
// private ImageView BackButton;
private DatabaseReference UsersRef, AllUserPartiesRef;
private FirebaseAuth mAuth;
String currentUserID;
@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.layout_all_horizontal_parties);
// Log.d(TAG, "onCreate: started.");
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
mAuth = FirebaseAuth.getInstance();
currentUserID = mAuth.getCurrentUser().getUid();
// UsersRef = FirebaseDatabase.getInstance().getReference().child("users").
AllUserPartiesRef = FirebaseDatabase.getInstance().getReference().child("all_user_parties").child(currentUserID);;
// BackButton = (ImageView) findViewById(R.id.backArrow);
//The next code is working on displaying all users posts
UserPartiesList = (RecyclerView) findViewById(R.id.horizontalRecycleView);
UserPartiesList.setHasFixedSize(true);
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(AllUserPartiesListActivity.this);
linearLayoutManager.setReverseLayout(true);
linearLayoutManager.setStackFromEnd(true);
UserPartiesList.setLayoutManager(linearLayoutManager);
// BackButton.setOnClickListener(new View.OnClickListener() {
// @Override
// public void onClick(View view) {
// Intent i = new Intent (getApplicationContext(),SearchActivity.class);
// startActivity(i);
// finish();
// }
// });
DisplayAllUsersData();
}
private void DisplayAllUsersData() {
Query SortPostsInDecendingOrder = AllUserPartiesRef.orderByKey();
FirebaseRecyclerAdapter<UserParties, PostsViewHolder> firebaseRecyclerAdapter = new FirebaseRecyclerAdapter<UserParties, PostsViewHolder>
(
UserParties.class,
R.layout.layout_horizontal_list_item,
PostsViewHolder.class,
SortPostsInDecendingOrder
) {
@Override
protected void populateViewHolder(final PostsViewHolder viewHolder, UserParties model, int position) {
//final String PostKey = getRef(position).getKey();
// final int PostIntKey=position; //var for store post position to return back the user here. Should be declare only here!!!!!!
final String UserKey = getRef(position).getKey();
viewHolder.setCreateAccTime(model.getCreateAccTime());
viewHolder.setParty(model.getParty());
}
};
UserPartiesList.setAdapter(firebaseRecyclerAdapter);
}
public static class PostsViewHolder extends RecyclerView.ViewHolder {
View mView;
public PostsViewHolder(View itemView) {
super(itemView);
mView = itemView;
}
public void setCreateAccTime(String createTime) {
TextView CreateTime = (TextView) mView.findViewById(R.id.name);
CreateTime.setText(createTime);
}
public void setParty(String party) {
ImageView UserPostParty = (ImageView) mView.findViewById(R.id.image_view);
Picasso.get().load(party).fit().into(UserPostParty);
}
}
以下也是相關的布局文件：
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_margin="1dp">
<android.support.v7.widget.CardView
android:layout_width="120dp"
android:layout_height="120dp"
app:cardCornerRadius="4dp"
app:cardMaxElevation="2dp"
app:cardElevation="1dp"
android:layout_centerInParent="true">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<de.hdodenhof.circleimageview.CircleImageView
android:layout_width="90dp"
android:layout_height="90dp"
android:scaleType="centerCrop"
android:layout_centerHorizontal="true"
android:id="@+id/image_view"
android:src="@drawable/ic_kulanu"
/>
<TextView
android:id="@+id/name"
android:layout_width="wrap_content"
android:layout_height="20dp"
android:text="Canada"
android:layout_below="@+id/image_view"
android:layout_centerHorizontal="true"
android:gravity="center"
android:layout_marginTop="1dp"
android:textColor="#000"
android:layout_marginBottom="1dp"
android:autoSizeTextType="uniform"
android:autoSizeMinTextSize="8sp"
android:autoSizeMaxTextSize="15sp"/>
</RelativeLayout>
</android.support.v7.widget.CardView>
</RelativeLayout>
完整的錯誤日志：
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.android.bluesky, PID: 32213
com.google.firebase.database.DatabaseException: Can't convert object of type java.lang.String to type com.example.android.bluesky.Admin.UserParties
at com.google.android.gms.internal.zg.zzb(Unknown Source:221)
at com.google.android.gms.internal.zg.zza(Unknown Source:0)
at com.google.firebase.database.DataSnapshot.getValue(Unknown Source:10)
at com.firebase.ui.database.ClassSnapshotParser.parseSnapshot(ClassSnapshotParser.java:22)
at com.firebase.ui.database.ObservableSnapshotArray.getObject(ObservableSnapshotArray.java:141)
at com.firebase.ui.database.CachingObservableSnapshotArray.getObject(CachingObservableSnapshotArray.java:40)
at com.firebase.ui.database.FirebaseRecyclerAdapter.getItem(FirebaseRecyclerAdapter.java:127)
at com.firebase.ui.database.FirebaseRecyclerAdapter.onBindViewHolder(FirebaseRecyclerAdapter.java:164)
at android.support.v7.widget.RecyclerView$Adapter.onBindViewHolder(RecyclerView.java:6673)
at android.support.v7.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:6714)
at android.support.v7.widget.RecyclerView$Recycler.tryBindViewHolderByDeadline(RecyclerView.java:5647)
at android.support.v7.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:5913)
at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5752)
at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5748)
at android.support.v7.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2232)
at android.support.v7.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1559)
at android.support.v7.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1519)
at android.support.v7.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:614)
at android.support.v7.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:3812)
at android.support.v7.widget.RecyclerView.dispatchLayout(RecyclerView.java:3529)
at android.support.v7.widget.RecyclerView.consumePendingUpdateOperations(RecyclerView.java:1767)
at android.support.v7.widget.RecyclerView$1.run(RecyclerView.java:356)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:949)
at android.view.Choreographer.doCallbacks(Choreographer.java:761)
at android.view.Choreographer.doFrame(Choreographer.java:693)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:935)
at android.os.Handler.handleCallback(Handler.java:873)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:6669)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
具有RecyclerView.Adapter的自定義實現的解決方案。
public class AllUserPartiesListActivity extends AppCompatActivity {
private static final String TAG = "AllUserPartiesListActivity";
private RecyclerView UserPartiesList;
private DatabaseReference UsersRef, AllUserPartiesRef;
private FirebaseAuth mAuth;
private String currentUserID;
@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.layout_all_horizontal_parties);
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
mAuth = FirebaseAuth.getInstance();
currentUserID = mAuth.getCurrentUser().getUid();
// *** You may call your variable AllUserPartiesRef yet you don't target all user parties,
// *** just one user's parties. This could be renamed to currentUserParties.
AllUserPartiesRef = FirebaseDatabase.getInstance().getReference().child("all_user_parties").child(currentUserID);;
//The next code is working on displaying all users posts
UserPartiesList = (RecyclerView) findViewById(R.id.horizontalRecycleView);
UserPartiesList.setHasFixedSize(true);
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(AllUserPartiesListActivity.this);
linearLayoutManager.setReverseLayout(true);
linearLayoutManager.setStackFromEnd(true);
UserPartiesList.setLayoutManager(linearLayoutManager);
DisplayAllUsersData();
}
private void DisplayAllUsersData() {
AllUserPartiesRef.addReValueEventListener(new ValueEventListener(){
@Override
public void onDataChange(DataSnapshot snapshot){
List<String> posts = new ArrayList<>();
for (DataSnapshot nameSnapshot : snapshot.getChildren()) {
String name = nameSnapshot.getValue(String.class);
String date = nameSnapshot.getKey();
String post = date + " " + name;
posts.add(post);
}
// *** Reaching this point posts list includes your previously fetched
// *** data in "date name" format, time to bind this data to the Adapter.
PostsAdapter adapter = new PostsAdapter(AllUserPartiesListActivity.this);
UserPartiesList.setAdapter(adapter);
// *** Adapter created, bind the posts and call notify
adapter.addPosts(posts);
adapter.notifyDatasetChanged();
}
@Override
public void onCancelled(DatabaseError error){}
});
}
public static class PostsAdapter extends RecyclerView.Adapter<PostsAdapter.PostsViewHolder>{
private Context context;
// This is your fetched data in a form of date+name String
// since you have only one textview to display this pair.
private List<String> posts;
public PostsAdapter(Context context) {
this.context = context;
}
public void addPosts(List<String> posts) {
this.posts = posts;
}
@NonNull
@Override
public PostsViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
LayoutInflater inflater = LayoutInflater.from(context);
View itemView = inflater.inflate(R.layout.layout_horizontal_list_item, viewGroup, false);
return new PostsViewHolder(itemView);
}
@Override
public void onBindViewHolder(@NonNull PostsViewHolder postsViewHolder, int position) {
if (posts != null && posts.size() > 0) {
postsViewHolder.bindPost(posts.get(position));
}
}
@Override
public int getItemCount() {
if (posts != null && posts.size() > 0) {
return posts.size();
}
return 0;
}
public static class PostsViewHolder extends RecyclerView.ViewHolder {
View mView;
TextView textView;
public PostsViewHolder(View itemView) {
super(itemView);
mView = itemView;
textView = (TextView) mView.findViewById(R.id.name);
}
public void setCreateAccTime(String createTime) {
TextView CreateTime = (TextView) mView.findViewById(R.id.name);
CreateTime.setText(createTime);
}
public void setParty(String party) {
ImageView UserPostParty = (ImageView) mView.findViewById(R.id.image_view);
Picasso.get().load(party).fit().into(UserPostParty);
}
public bindPost(String post){
textView.setText(post);
}
}
}
}
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