Firebase-Kinder zu RecyclerView

Question

Ich benutze Firebase und ich muss Kinder auf den RecyclerView nicht FirebaseRecyclerAdapter abrufen, damit ich die Kinder zum RecyclerView abrufen muss.

Hier ist meine Firebase Datenbankstruktur:

"Following" : { 
    "ORBBKfZAAUhqI1h7ojQDzYOjgkp1" : { 
     "pypD1SYZkbcYesk09WuMUY1AkTf1" : { 
     "UID" : "pypD1SYZkbcYesk09WuMUY1AkTf1" 
     }, 
     "z2SNUlLd6mQM8nnlkU2VUws5Ggl2" : { 
     "UID" : "z2SNUlLd6mQM8nnlkU2VUws5Ggl2" 
     } 
    }, 
    "Posts" : { 
    "-KduqnVVczZf5uibQiZ-" : { 
     "Describe" : "gg", 
     "MostView" : -8, 
     "Time" : 14881230655, 
     "UID" : "pypD1SYZkbcYesk09WuMUY1AkTf1", 
     "Username" : "Jone", 
     "Wallpaper" : "https://firebasestorage.googleapis.com/v0/b/test-3f4c5.appspot.com/o/Posts%2Fcropped906285501.jpg?alt=media&token=0c1a3a3d-6e48-4c4e-ba59-f5646bf8965f" 
    }, 
    "-Ke5gJ00CxbjhOuhzLIx" : { 
     "Describe" : "hajj", 
     "MostView" : -9, 
     "Time" : 1488318465, 
     "UID" : "pypD1SYZkbcYesk09WuMUY1AkTf1", 
     "Username" : "Dom", 
     "Wallpaper" : "https://firebasestorage.googleapis.com/v0/b/test-3f4c5.appspot.com/o/Posts%2Fcropped1717103943.jpg?alt=media&token=a85b2488-5ac7-49a7-9ad0-dbf4e6f29389" 
    }, 
    "-KeCuiFmUCpN19zwsTsR" : { 
     "Describe" : "a", 
     "MostView" : -2, 
     "Profile" : "https://lh4.googleusercontent.com/-suB77riNoX8/AAAAAAAAAAI/AAAAAAAAAAA/ADPlhfKMzINn-Ki538Sqf6SRGaXC81-WuQ/s200-c/photo.jpg", 
     "Time" : 1488439652, 
     "UID" : "z2SNUlLd6mQM8nnlkU2VUws5Ggl2", 
     "Username" : "Dom", 
     "Wallpaper" : "https://firebasestorage.googleapis.com/v0/b/test-3f4c5.appspot.com/o/Posts%2Fcropped1913886685.jpg?alt=media&token=c8ad26b2-8f09-453b-b48a-aad9e4d8b5c3" 
    }, 
    "-KeD2fBUQ09HVMrvAneb" : { 
     "Describe" : "ee", 
     "MostView" : -2, 
     "Profile" : "https://lh4.googleusercontent.com/-suB77riNoX8/AAAAAAAAAAI/AAAAAAAAAAA/ADPlhfKMzINn-Ki538Sqf6SRGaXC81-WuQ/s200-c/photo.jpg", 
     "Time" : 1488441999, 
     "UID" : "z2SNUlLd6mQM8nnlkU2VUws5Ggl2", 
     "Username" : "Dom", 
     "Wallpaper" : "https://firebasestorage.googleapis.com/v0/b/test-3f4c5.appspot.com/o/Posts%2Fcropped1904338270.jpg?alt=media&token=d200b7fc-15e7-4dc4-9913-59c377929e9e" 
    }, 
    "-KeDfnMWiB7k_4J3FBgZ" : { 
     "Describe" : "f12g", 
     "MostView" : -1, 
     "Time" : 1488452517, 
     "UID" : "ORBBKfZAAUhqI1h7ojQDzYOjgkp1" 
     "Username" : "Young", 
     "Wallpaper" : "https://firebasestorage.googleapis.com/v0/b/test-3f4c5.appspot.com/o/Posts%2Fcropped1872832638.jpg?alt=media&token=80239844-a872-47e2-9689-92d368dd9452" 
    }, 
    "-KeDfrw4inUQFtIDXJHp" : { 
     "Describe" : "fg", 
     "MostView" : -2, 
     "Time" : 1488452536, 
     "UID" : "ORBBKfZAAUhqI1h7ojQDzYOjgkp1" 
     "Username" : "Young", 
     "Wallpaper" : "https://firebasestorage.googleapis.com/v0/b/test-3f4c5.appspot.com/o/Posts%2Fcropped1872832638.jpg?alt=media&token=80239844-a872-47e2-9689-92d368dd9452" 
    }, 

    } 
} 

I Beitrag für die folgenden Benutzer zu zeigen, brauchen nur so habe ich diese Methode:

mPostList = (RecyclerView) v.findViewById(R.id.MainPostList); 
    mPostList.setHasFixedSize(true); 
    mPostList.setItemAnimator(new DefaultItemAnimator()); 
    LinearLayoutManager layoutManager = new LinearLayoutManager(getActivity()); 
    mPostList.setLayoutManager(layoutManager); 

    mAuth = FirebaseAuth.getInstance(); 
    mCurrentUser = mAuth.getCurrentUser(); 

    mDatabase = FirebaseDatabase.getInstance().getReference().child("Posts"); 
    mDatabaseUsers = FirebaseDatabase.getInstance().getReference().child("Users"); 
    mDatabaseFriends = FirebaseDatabase.getInstance().getReference().child("Following").child(mCurrentUser.getUid()); 

    return v; 
} 

@Override 
public void onStart() { 
    super.onStart(); 

    mAuth.addAuthStateListener(mListener); 

    mDatabaseFriends.addValueEventListener(new ValueEventListener() { 
     @Override 
     public void onDataChange(DataSnapshot dataSnapshot2) { 

      for (DataSnapshot GettingFollowingList : dataSnapshot2.getChildren()){ 
       mDatabase.orderByChild("UID").equalTo(GettingFollowingList.getKey()).addValueEventListener(new ValueEventListener() { 
        @Override 
        public void onDataChange(DataSnapshot dataSnapshot) { 
         for (DataSnapshot Q : dataSnapshot.getChildren()){ 

          Adapter MyAdapter = Q.getValue(Adapter.class); 
          mPostList.setAdapter(MyAdapter);}} 
        @Override 
        public void onCancelled(DatabaseError databaseError) { 

        }});}} 

     @Override 
     public void onCancelled(DatabaseError databaseError) { 

     }}); 

Und hier ist mein Adapter:

class Adapter extends RecyclerView.Adapter<PostViewHolder> { 
ArrayList<Getting_Posts> mdataSet; 

public Adapter(ArrayList<Getting_Posts> dataSet){ 
    mdataSet = dataSet; 
} 

@Override 
public PostViewHolder onCreateViewHolder(ViewGroup parent, int viewType) { 
    View inflatedView = LayoutInflater.from(parent.getContext()).inflate(R.layout.post_card_design, parent, false); 
    return new PostViewHolder(inflatedView); 
} 

@Override 
public void onBindViewHolder(final PostViewHolder holder, int position) { 
    Getting_Posts model = mdataSet.get(position); 

    //model.getTime(); 
    //holder.mPostTime.setText("Q"); 
    // Set the properties of the holder 
    // I don't know what properties you used in the viewholder so I'll just give an example 
    // example: holder.Name.setText(post.getName()); 
} 

@Override 
public int getItemCount() { 
    return mdataSet.size(); 
} 

public void add(int position, Getting_Posts post) { 
    mdataSet.add(position, post); 
    notifyItemInserted(position); 
} 

Und hier ist mein erster Beitrag:

public class Getting_Posts { 

//Post 
private Long Time; 
private String Describe; 
private String Wallpaper; 
private String Username; 
private String ProfilePic; 

public Getting_Posts() {} 

public Getting_Posts 
     (Long Time, 
     String Describe, 
     String Wallpaper, 
     String Username; 
     String ProfilePic; 
     ) { 

    this.Time = Time; 
    this.Describe = Describe; 
    this.Wallpaper = Wallpaper; 
    this.Username = Username; 
    this.ProfilePic = ProfilePic; 

} 

public Long getTime() { 
    return Time; 
} 

public void setTime(Long time) { 
    Time = time; 
} 

public String getDescribe() { 
    return Describe; 
} 

public void setDescribe(String describe) { 
    Describe = describe; 
} 

public String getWallpaper() { 
    return Wallpaper; 
} 

public void setWallpaper(String wallpaper) { 
    Wallpaper = wallpaper; 
} 

public String getUsername() { 
    return Username; 
} 

public void setUsername(String username) { 
    Username = username; 
} 

public String getProfilePic() { 
    return ProfilePic; 
} 

public void setProfilePic(String profilepic) { 
    ProfilePic = profilepic; 
} 

aber Ich bin immer diese Fehlermeldung:

com.google.firebase.database.DatabaseException: Class com.pcsoftgroup.test.fragments.Adapter is missing a constructor with no arguments 
                     at com.google.android.gms.internal.zzalq$zza.zze(Unknown Source) 
                     at com.google.android.gms.internal.zzalq$zza.zzcc(Unknown Source) 
                     at com.google.android.gms.internal.zzalq.zzd(Unknown Source) 
                     at com.google.android.gms.internal.zzalq.zzb(Unknown Source) 
                     at com.google.android.gms.internal.zzalq.zza(Unknown Source) 
                     at com.google.firebase.database.DataSnapshot.getValue(Unknown Source) 
                     at com.pcsoftgroup.test.fragments.MainChallenges$3$1.onDataChange(MainChallenges.java:151) 

Answer 1

Im Allgemeinen, wenn Sie die Feuerbasis Daten mit einer Modellklasse ordnen Sie einen leeren Konstruktor hinzuzufügen haben.

In Ihrem Fall Sie die Abbildung der Daten mit dem Adapter Klasse

Adapter MyAdapter = Q.getValue(Adapter.class);

so sollten Sie den Konstruktor in dieser Klasse hinzuzufügen.

class Adapter { 

    public Adapter() { 
      // Default constructor required for calls to DataSnapshot.getValue(Adapter.class) 
    } 

} 

In Ihrem Fall es macht keinen Sinn.
Sie sollten auf die Kinder fahren (zum Beispiel die Getting_Posts Referenz) und dann jedes Kind mit einem Getting_Posts abbilden und sie dem Adapter hinzufügen (eine Liste davon).

Etwas wie:

for (DataSnapshot Q : dataSnapshot.getChildren()){ 
       myList.add(Q.getValue(Getting_Posts.class); 
} 
myAdapter.setList(myList); 

In jedem Fall, dass Sie Firebase UI versuchen sollte.
Es ist sehr einfach, einen RecyclerView mit Firebase Daten zu füllen.