我的应用程序有一个包含项目列表的主要活动（比如项目A和项目B），每个项目都会启动相同的活动（UserGalleryActivity），但活动中的recyclerView应该只显示与项目相关的项目（让我们称之为项目） A）在MainActivity中选择。
我的问题是，如果我首先选择（例如）项目A，它可以正常工作，UserGalleryActivity中的RecyclerView只显示A的项目，但是当我回到MainActivity并选择B时，UserGalleryActivity向我显示A的项目和B的项目。
我该如何解决这个问题？任何的想法？先感谢您
亚瑟画廊活动代码：
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_user_gallery);
//L'activity riceve tramite intent dal main l'oggetto User
Intent intent = getIntent();
int user = intent.getIntExtra("user", -1);
System.out.println("UserIndex: " + user);
System.out.println(UsersSingleton.getInstance().getArray().get(user).getPhotos().size());
if(user >= 0 && user<=UsersSingleton.getInstance().getArray().size()){
String username = UsersSingleton.getInstance().getArray().get(user).getUsername();
username = username.substring(0, 1).toUpperCase() + username.substring(1);
UserGalleryActivity.this.setTitle(username);
System.out.println("UserIndex: " + user);
//System.out.println(UsersSingleton.getInstance().getArray().get(user).getPhotos().get(0).toString());
setRecycleView(user);
}
}
//Al termine della creazione dell'arraylist di users viene invocata setReView con parameto l'arraylist creato
private void setRecycleView(int userIndex){
RecyclerView recyclerView = findViewById(R.id.photosList);
recyclerView.setHasFixedSize(true);
RecyclerView.LayoutManager layoutManager = new GridLayoutManager(this,2);
recyclerView.setLayoutManager(layoutManager);
MyAdapterPhotos adapter = new MyAdapterPhotos(this, userIndex);
recyclerView.setAdapter(adapter);
MyAdapter的照片代码：
private int usersIndex;
private Context context;
JSONHelper jsonHelper;
URLHelper urlHelper;
ArrayList<Photo> photosList;
//Bitmap bitmap;
public MyAdapterPhotos(Context context, int usersList) {
this.context = context;
this.usersIndex = usersList;
jsonHelper = new JSONHelper();
urlHelper = new URLHelper();
photosList = new ArrayList<>();
}
@NonNull
@Override
public MyAdapterPhotos.ViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.cell_layout_gallery,
viewGroup, false);
return new ViewHolder(view);
}
@Override
public void onBindViewHolder(@NonNull ViewHolder holder, final int position) {
if (UsersSingleton.getInstance().getArray().get(usersIndex).getPhotos().get(position) != null){
holder.title.setText(UsersSingleton.getInstance().getArray().get(usersIndex).getPhotos().get(position).getCity());
holder.img.setScaleType(ImageView.ScaleType.CENTER_CROP);//prima era centercrop
String username = UsersSingleton.getInstance().getArray().get(usersIndex).getUsername();
username = username.substring(0, 1).toUpperCase() + username.substring(1);
holder.author.setText(username);
System.out.println("Numero di Foto: " + UsersSingleton.getInstance().getArray().get(usersIndex).getPhotos().size());
System.out.println("Posizione: " + position);
System.out.println(UsersSingleton.getInstance().getArray().get(usersIndex).getPhotos().get(position).toString());
setImage(UsersSingleton.getInstance().getArray().get(usersIndex).getPhotos().get(position).getSmall(), holder.img);
}
}
@Override
public int getItemCount() {
return UsersSingleton.getInstance().getArray().get(usersIndex).getPhotos().size();
}
public class ViewHolder extends RecyclerView.ViewHolder{
private TextView title;
private ImageView img;
private TextView author;
public ViewHolder(View view){
super(view);
title = view.findViewById(R.id.title_g);
img = view.findViewById(R.id.img_g);
author = view.findViewById(R.id.author_g);
// on image item click
img.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View v) {
// get position
int pos = getAdapterPosition();
// check if item still exists
if(pos != RecyclerView.NO_POSITION){
int clickedDataItem = pos;
/* for future animation
if (img.getDrawable() != null) {
bitmap = ((BitmapDrawable) img.getDrawable()).getBitmap();
} */
//se l'array di photo dell'utente è ancora vuoto, scaricale. altrimenti usa quelle che hai gia
Intent photosIntent = new Intent(context, PhotoDetailActivity.class);
photosIntent.putExtra("user", usersIndex);
photosIntent.putExtra("photo", clickedDataItem);
context.startActivity(photosIntent);
/* for future animations
ActivityTransitionLauncher.with((AppCompatActivity) context)
.from(img)
.image(bitmap)
.launch(photosIntent);*/
//se l'array di photo dell'utente è ancora vuoto, scaricale. altrimenti usa quelle che hai gia
}
}
});
// on title item click
view.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View v) {
// get position
int pos = getAdapterPosition();
// check if item still exists
if(pos != RecyclerView.NO_POSITION){
//Photo clickedDataItem = UsersSingleton.getInstance().getArray().get(usersIndex).getPhotos().get(pos);
int clickedDataItem = pos;
//se l'array di photo dell'utente è ancora vuoto, scaricale. altrimenti usa quelle che hai gia
Intent photosIntent = new Intent(context, PhotoDetailActivity.class);
photosIntent.putExtra("user", usersIndex);
photosIntent.putExtra("photo", clickedDataItem);
context.startActivity(photosIntent);
//Toast.makeText(v.getContext(), "You clicked " + clickedDataItem, Toast.LENGTH_SHORT).show();
}
}
});
}
}
// metodo set immagine dell'utente dell'imageview
private void setImage(String imageUrl, ImageView img){
CircularProgressDrawable circularProgressDrawable =
new CircularProgressDrawable(context);
circularProgressDrawable.setStrokeWidth(5f);
circularProgressDrawable.setCenterRadius(30f);
circularProgressDrawable.start();
GlideApp.with(context)
.load(imageUrl)
.placeholder(circularProgressDrawable)
.into(img);
}
听到是个主意：
首先，您应该清除列表，然后再添加其他数据
yourlist.clear();
// then add item B to your list and call adapter
示例：
// Items :
Room A = new Room();
Room B = new Room();
// THEN FILL A AND B ...
如下填充列表和呼叫适配器：
List<Room> roomList = new ArrayList<>();
roomList.add(A);
Adapter adapter = new Adapter(roomList , getContext(), this);
recyclerView.setLayoutManager(new GridLayoutManager(getActivity() , 1));
recyclerView.setAdapter(adapter);
我认为你没有从项目A清除你的清单：
roomList.clear();
roomList.add(B);
// adapter.notifyDataSetChanged(); Or :
adapter = new Adapter(roomList , getContext(), this);
recyclerView.setLayoutManager(new GridLayoutManager(getActivity() , 1));
recyclerView.setAdapter(adapter);