Question

我的应用程序使用firebase RecyclerAdapter来显示活动中的“植物”实体。我这样做的目的是，如果我使用ViewHolder和RecyclerAdapter长按Cardview格式显示的实体，它将提示执行删除，并删除Firebase数据库和存储上的工厂实体+映像。删除和添加植物可以在后端轻松进行，因为我可以在Firebase数据库中确认这一点。

但是，当我删除一个“植物”实体并添加一个新实体时，CardView会显示上一个或另一个图像。删除应用程序并重新安装它似乎可以解决问题，因此，我认为这可能与本地缓存有关。

PlantActivity.java（加载植物的位置）我想如果有某种方法可以刷新活动或使用RecyclerAdapter可以解决此问题……尽管我已经尝试了很多事情

公共类PlantActivity扩展了AppCompatActivity {

private static final int ADD_REQUEST = 101;
private static final String TAG = "PlantActivityView";
private DatabaseReference mDatabaseReference;
private FirebaseRecyclerAdapter plantAdapter;
private PlantDAO mPlantDAO;
private UserDAO mUserDAO;
private CoordinatorLayout coordinatorLayout;

@Override
protected void onStart() {
    super.onStart();
    if(!mUserDAO.isLoggedIn()){
        finish();
        startActivity(new Intent(PlantActivity.this, LoginActivity.class));
    }
    plantAdapter.startListening();
}
@Override
protected void onStop() {
    super.onStop();
    plantAdapter.stopListening();
}

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_plant_view);

    FirebaseDatabase.getInstance().setPersistenceEnabled(true);
    mDatabaseReference = FirebaseDatabase.getInstance().getReference();
    mPlantDAO = new PlantDAO(mDatabaseReference);
    mUserDAO = new UserDAO();

    //make custom appcompat toolbar to replace actionbar and add logout item
    Toolbar toolbar = findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    coordinatorLayout = findViewById(R.id.plant_coordinator);
    providePlantsOfCurrentUser();

    findViewById(R.id.fab).setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent intent = new Intent(getApplicationContext(),PlantAddActivity.class);
            startActivityForResult(intent, ADD_REQUEST);
        }
    });
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.menu, menu);
    return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()){
        case R.id.menuLogout:
            mUserDAO.getAuth().signOut();
            finish();
            startActivity(new Intent(PlantActivity.this,LoginActivity.class));
            return true;
        default:
            return super.onOptionsItemSelected(item);
    }
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    Snackbar GoodResultSnackbar = Snackbar.make(coordinatorLayout,"PLANT ADDED",Snackbar.LENGTH_SHORT);
    Snackbar BadResultSnackbar = Snackbar.make(coordinatorLayout,"PLANT ADD FAILED",Snackbar.LENGTH_SHORT);
    if(requestCode == ADD_REQUEST){
        if(resultCode == Activity.RESULT_OK){
           GoodResultSnackbar.show();
        } else if(resultCode == Activity.RESULT_CANCELED){
            BadResultSnackbar.show();
        }
    }
    super.onActivityResult(requestCode, resultCode, data);
}


public void providePlantsOfCurrentUser(){
    FirebaseRecyclerOptions<Plant> options = new FirebaseRecyclerOptions.Builder<Plant>().setQuery(mPlantDAO.currentUserPlantsQuery(), Plant.class).build();
    plantAdapter = new FirebaseRecyclerAdapter<Plant,PlantViewHolder>(options) {
        @NonNull
        @Override
        public PlantViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
            View view = LayoutInflater.from(parent.getContext())
                    .inflate(R.layout.cardview_item_plant, parent, false);
            return new PlantViewHolder(view);
        }

        @Override
        protected void onBindViewHolder(@NonNull final PlantViewHolder holder, final int position, @NonNull final Plant model) {
            StorageReference localstorage = FirebaseStorage.getInstance().getReferenceFromUrl(model.getImageLocation());
            String plantText = /*model.getPlantID() + ": " + */ model.getPlanttype();

            holder.tv_plant_name.setText(plantText);
            //image implementation
            GlideApp.with(getApplicationContext()).load(localstorage).into(holder.img_plant_thumbnail);

            holder.dialogClickListener = new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    switch (which){
                        case DialogInterface.BUTTON_POSITIVE:
                            mPlantDAO.deletePlant(model.getPlantID());
                            plantAdapter.notifyDataSetChanged();
                            break;

                        case DialogInterface.BUTTON_NEGATIVE:
                            //Return
                            break;
                    }
                }
            };

            holder.cardView.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    //passing data with intent to PlantDetailActivity instance
                    Intent intent = new Intent(getApplicationContext(), PlantDetailActivity.class);
                    intent.putExtra("plantID", model.getPlantID());
                    intent.putExtra("planttype", model.getPlanttype());
                    //image implementation
                    intent.putExtra("image_url", model.getImageLocation());
                    //start the activity
                    startActivity(intent);

                }
            });
            holder.cardView.setOnLongClickListener(new View.OnLongClickListener() {
                @Override
                public boolean onLongClick(View v) {
                   showDeleteDialog(holder);
                    return true;
                }
            });
        }
    };
    RecyclerView recyclerView = findViewById(R.id.recyclerview_id);
    recyclerView.setAdapter(plantAdapter);
    recyclerView.setLayoutManager(new GridLayoutManager(this, 3));
}

private void showDeleteDialog(PlantViewHolder holder){
    AlertDialog.Builder builder = new AlertDialog.Builder(this);
    builder.setMessage("Delete this plant?").setPositiveButton("Yes", holder.dialogClickListener)
            .setNegativeButton("Cancel", holder.dialogClickListener).show();
}

}

Answer 1

位置和模型在onBindViewHolder方法上是最终的

观看者可以是最终的，但不能是数据或位置

使用holder.getAdapterPosition（）获取匿名界面（如点击监听器）中的位置

然后使用适配器类中的getItem（）方法获取数据

Answer 2

@cutiko的最后答案肯定有帮助！但是我想我意识到了问题。我以这种方式保存了（新Plant对象的）plantID字符串属性：数据库中“ plants”的“ plant _” + count（） +“ _” + 当前用户的ID +“。jpg”

这引起的问题是，当我删除一个工厂实体并添加另一个工厂实体时，这可能导致数据库中的2个工厂实体具有相同的ID，这会导致奇怪的行为。

我将通过以下方法解决此问题，而不是从数据库中删除植物，将新属性的（“ active”）更改为false并在FirebaseRecyclerAdapter中不显示这些属性

Firebase recycleradapter显示错误信息Android

2 个答案: