Stackpile:
Actualización : Uno de los problemas está resuelto: Ahora updateListse ha resuelto, el problema era que he definido mAdaptercomo RecyclerView.Adapterlugar de MyAdapter. Pero ahora, aunque yo estoy recibiendo datos, no aparece nada en la lista, que está vacío
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Quiero actualizar mi RecyclerViewusando DiffUtilpara evitar duplicados.
Tengo 4 clases: la clase de usuario, la Activityclase en la que conjunto de datos, la Adapterclase y la DiffUtilclase. No estoy seguro de que combinar todos estos 4 correctamente.
Esta es la clase de usuario:
public class User {
private String mUserId;
private Uri mImageUrl;
public User(String userId, String imageUrl) {
mUserId = userId;
mImageUrl = Uri.parse(imageUrl);
}
public String getUserId() {
return mUserId;
}
public Uri getImageUrl() {
return mImageUrl;
}
}
Así es como me conjunto de datos de forma dinámica (sigo recibiendo nuevas Jsonmatrices desde el servidor que contiene a visualizar de identificación del usuario, entonces me puse la imagen del usuario de Firebasealmacenamiento): (Es una función invocada por un oyente onClick :)
Esta es la llamada de método a partir del fragmento:
button.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
updateUsersList();
}
});
Esta es la función:
private void updateUsersList() {
@Override
public void onResponse(JSONArray response) { // the JSON ARRAY response of user ids ["uid1", "uid334", "uid1123"]
myDataset.clear(); // clear dataset to prevent duplicates
for (int i = 0; i < response.length(); i++) {
try {
String userKey = response.get(i).toString(); // the currently iterated user id
final DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference userKeyRef = rootRef.child("users").child(userKey); // reference to currently iterated user
ValueEventListener listener = new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
myDataset.add(new User(dataSnapshot.getKey(), dataSnapshot.child("imageUrl").getValue().toString())); //add new user: id and image url
mAdapter.updateList(myDataset); // cannot resolve this method, why?
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
Log.d(TAG, databaseError.getMessage());
}
};
userKeyRef.addListenerForSingleValueEvent(listener);
}
catch (JSONException e) { Log.d(TAG, "message " + e); }
}
}
Así es como mi DiffUtilclase se parece a:
public class MyDiffUtilCallBack extends DiffUtil.Callback{
ArrayList<User> oldUsers;
ArrayList<User> newUsers;
public MyDiffUtilCallBack(ArrayList<User> newUsers, ArrayList<User> oldUsers) {
this.newUsers = newUsers;
this.oldUsers = oldUsers;
}
@Override
public int getOldListSize() {
return oldUsers.size();
}
@Override
public int getNewListSize() {
return newUsers.size();
}
@Override
public boolean areItemsTheSame(int oldItemPosition, int newItemPosition) {
return oldUsers.get(oldItemPosition).getUserId().equals( newUsers.get(newItemPosition).getUserId());
}
@Override
public boolean areContentsTheSame(int oldItemPosition, int newItemPosition) {
return oldUsers.get(oldItemPosition).equals(newUsers.get(newItemPosition));
}
@Nullable
@Override
public Object getChangePayload(int oldItemPosition, int newItemPosition) {
//you can return particular field for changed item.
return super.getChangePayload(oldItemPosition, newItemPosition);
}
}
Y esta es mi adaptador:
public class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyViewHolder> {
private ArrayList<User> mDataset;
private MyViewHolder myHolder;
private User user;
public static class MyViewHolder extends RecyclerView.ViewHolder {
public TextView singleItemTextView;
public ImageView singleItemImage;
public View layout;
public ConstraintLayout constraintLayout;
public MyViewHolder(View v) {
super(v);
layout = v;
singleItemImage = (ImageView) v.findViewById(R.id.icon);
singleItemTextView = (TextView) v.findViewById(R.id.singleitemtv);
constraintLayout = (ConstraintLayout) v.findViewById(R.id.nbConstraintLayout);
}
}
// Provide a suitable constructor (depends on the kind of dataset)
public MyAdapter(ArrayList<User> myDataset) {
mDataset = myDataset;
}
// Create new views (invoked by the layout manager)
@Override
public MyAdapter.MyViewHolder onCreateViewHolder(ViewGroup parent,
int viewType) {
View v = LayoutInflater.from(parent.getContext())
.inflate(R.layout.nb_image_view, parent, false);
MyViewHolder vh = new MyViewHolder(v);
return vh;
}
@Override
public void onBindViewHolder(final MyViewHolder holder, final int position) {
myHolder = holder;
user = mDataset.get(position);
Uri userImage = user.getImageUrl();
myHolder.singleItemTextView.setText(user.getUserId());
Glide.with(myHolder.itemView.getContext() /* context */)
.load(userImage)
.into(myHolder.singleItemImage);
myHolder.constraintLayout.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Context context = v.getContext();
Intent intent = new Intent(v.getContext(), DisplayUserActivity.class);
context.startActivity(intent);
}
});
}
public void updateList(ArrayList<User> newList) {
DiffUtil.DiffResult diffResult = DiffUtil.calculateDiff(new MyDiffUtilCallBack(this.mDataset, newList));
diffResult.dispatchUpdatesTo(this);
}
}
No estoy seguro de que combinar todas las clases correctamente (mi primera vez usando DiffUtil), y también consigocannot resolve method updateList(?)
¿Qué estoy haciendo mal?
Esto es como defino mAdapter en mi Fragmento:
public class MyFragment extends Fragment {
private ArrayList<User> myDataset;
private RecyclerView.Adapter mAdapter;
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
rootView = inflater.inflate(R.layout.fragment_lks, container, false);
mRecyclerView = (RecyclerView) rootView.findViewById(R.id.my_recycler_view);
myDataset = new ArrayList<User>();
mAdapter = new MyAdapter(myDataset);
aminography:
El problema viene de definición mAdapter. Que ha definido como RecyclerView.Adapterque es super clase de tu MyAdaptery que no contiene updateList(). Se debe cambiar de la siguiente manera:
private MyAdapter mAdapter;
Actualización 13/01/2019:
Tengo volvió a escribir su adaptador con el AsyncListDifferque calcula el diffrence de forma asíncrona a continuación, se aplica al adaptador.
MyAdapter.java
import android.content.Context;
import android.content.Intent;
import android.net.Uri;
import android.support.annotation.NonNull;
import android.support.constraint.ConstraintLayout;
import android.support.v7.recyclerview.extensions.AsyncListDiffer;
import android.support.v7.util.DiffUtil;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import com.bumptech.glide.Glide;
import java.util.List;
public class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyViewHolder> {
private AsyncListDiffer<User> mAsyncListDiffer;
public static class MyViewHolder extends RecyclerView.ViewHolder {
public TextView singleItemTextView;
public ImageView singleItemImage;
public View layout;
public ConstraintLayout constraintLayout;
public MyViewHolder(View v) {
super(v);
layout = v;
singleItemImage = (ImageView) v.findViewById(R.id.icon);
singleItemTextView = (TextView) v.findViewById(R.id.singleitemtv);
constraintLayout = (ConstraintLayout) v.findViewById(R.id.nbConstraintLayout);
}
}
// Provide a suitable constructor (depends on the kind of dataset)
public MyAdapter() {
DiffUtil.ItemCallback<User> diffUtilCallback = new DiffUtil.ItemCallback<User>() {
@Override
public boolean areItemsTheSame(@NonNull User newUser, @NonNull User oldUser) {
return newUser.getUserId().equals(oldUser.getUserId());
}
@Override
public boolean areContentsTheSame(@NonNull User newUser, @NonNull User oldUser) {
return newUser.equals(oldUser);
}
};
mAsyncListDiffer = new AsyncListDiffer<>(this, diffUtilCallback);
}
// Create new views (invoked by the layout manager)
@Override
public MyAdapter.MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.nb_image_view, parent, false);
MyViewHolder vh = new MyViewHolder(v);
return vh;
}
@Override
public void onBindViewHolder(final MyViewHolder holder, final int position) {
User user = mAsyncListDiffer.getCurrentList().get(position);
Uri userImage = user.getImageUrl();
holder.singleItemTextView.setText(user.getUserId());
Glide.with(holder.itemView.getContext() /* context */)
.load(userImage)
.into(holder.singleItemImage);
holder.constraintLayout.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Context context = v.getContext();
Intent intent = new Intent(v.getContext(), DisplayUserActivity.class);
context.startActivity(intent);
}
});
}
@Override
public int getItemCount() {
return mAsyncListDiffer.getCurrentList().size();
}
public void updateList(List<User> newList) {
mAsyncListDiffer.submitList(newList);
}
}
User.java
public class User {
private String mUserId;
private Uri mImageUrl;
public User(String userId, String imageUrl) {
mUserId = userId;
mImageUrl = Uri.parse(imageUrl);
}
public String getUserId() {
return mUserId;
}
public Uri getImageUrl() {
return mImageUrl;
}
@Override
public boolean equals(Object other) {
if (other instanceof User) {
User user = (User) other;
return mUserId.equals(user.getUserId()) && mImageUrl.equals(user.getImageUrl());
} else {
return false;
}
}
}