如何修复 Recyclerview 项目删除显示错误
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【中文标题】如何修复 Recyclerview 项目删除显示错误【英文标题】:How can I fix Recyclerview item deletion display error 【发布时间】:2022-01-16 09:39:27 【问题描述】:我有一个回收站视图。 recyclerview中有城市名称,当我长按时,我想从recyclerview中删除它。我在适配器类中写了一些代码。当我点击城市名称时,我可以删除它们,但是当我再次查看recyclerview时,我删除的城市名称又出现了。我该如何解决这个问题?
我的适配器类
public class Adapter extends RecyclerView.Adapter<Adapter.MyViewHolder>
ArrayList<City> arrayList;
Context context;
public Adapter(ArrayList<City> arrayList ,Context context )
this.arrayList = arrayList;
this.context = context;
@NonNull
@Override
public MyViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType)
RecyclerviewRowBinding recyclerviewRowBinding = RecyclerviewRowBinding.inflate(LayoutInflater.from(parent.getContext()),parent,false);
return new MyViewHolder(recyclerviewRowBinding);
@Override
public void onBindViewHolder(@NonNull Adapter.MyViewHolder holder, int position)
holder.binding.MytxtCities.setText(arrayList.get(position).cityName);
holder.itemView.setOnLongClickListener(new View.OnLongClickListener()
@Override
public boolean onLongClick(View v)
AlertDialog.Builder builder = new AlertDialog.Builder(context);
builder.setIcon(R.drawable.warningicon);
builder.setMessage("Are you sure that you want to delete "+arrayList.get(position).cityName);
builder.setPositiveButton("Ok", new DialogInterface.OnClickListener()
@Override
public void onClick(DialogInterface dialog, int which)
arrayList.remove(position);
notifyItemRemoved(position);
notifyItemRangeChanged(position,arrayList.size());
).setNegativeButton("Cancel", new DialogInterface.OnClickListener()
@Override
public void onClick(DialogInterface dialog, int which)
).show();
return true;
);
holder.itemView.setOnClickListener(v ->
Intent intent = new Intent(holder.itemView.getContext(),MainActivity.class);
intent.putExtra("citId",arrayList.get(position).id);
holder.itemView.getContext().startActivity(intent);
);
@Override
public int getItemCount()
return arrayList.size();
public class MyViewHolder extends RecyclerView.ViewHolder
TextView Mytxt_cities;
private RecyclerviewRowBinding binding;
public MyViewHolder(@NonNull RecyclerviewRowBinding binding)
super(binding.getRoot());
this.binding = binding;
Mytxt_cities = itemView.findViewById(R.id.Mytxt_cities);
我的 recyclerview 类是城市类
public class cities extends AppCompatActivity
RecyclerView recyclerView ;
ArrayList<City> cityArrayList;
Adapter cityadapter;
ImageView cities_back_icon;
public void init()
cities_back_icon = findViewById(R.id.Id_cities_back_icon);
cities_back_icon_click_register();
cityArrayList = new ArrayList<>();
recyclerView = findViewById(R.id.recyclerview_id);
SQLGet_Data();
@Override
protected void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_cities);
init();
private void cities_back_icon_click_register()
cities_back_icon.setOnClickListener(new View.OnClickListener()
@Override
public void onClick(View v)
Intent intent = new Intent(cities.this, MainActivity.class);
startActivity(intent);
);
private void SQLGet_Data()
try
SQLiteDatabase sqLiteDatabase = this.openOrCreateDatabase("City",MODE_PRIVATE,null);
Cursor cursor = sqLiteDatabase.rawQuery("SELECT*FROM city",null);
int idIx = cursor.getColumnIndex("id");
int nameIx = cursor.getColumnIndex("cityname");
while(cursor.moveToNext())
String cityname = cursor.getString(nameIx);
int id = cursor.getInt(idIx);
City city = new City(cityname,id);
cityArrayList.add(city);
cityadapter.notifyDataSetChanged();
cursor.close();
catch (Exception e )
e.printStackTrace();
/*---------------------- set recyclerview-----------------------------*/
recyclerView.setLayoutManager(new LinearLayoutManager(cities.this));
cityadapter = new Adapter(cityArrayList,this);
recyclerView.setAdapter(cityadapter);
/*--------------------------We drew a line between the data in the recyclerview------------------------------------*/
DividerItemDecoration dividerItemDecoration = new DividerItemDecoration(recyclerView.getContext(), DividerItemDecoration.VERTICAL);
Drawable drawable = ContextCompat.getDrawable(getApplicationContext(), R.drawable.custom_divider);
dividerItemDecoration.setDrawable(drawable);
recyclerView.addItemDecoration(dividerItemDecoration);
【问题讨论】:
您正在从 SQL 数据库中检索数据,但仅从列表中删除该项目。要完全删除该项目以使其不再显示,您还必须将其从数据库中删除。 【参考方案1】:问题是您只是从适配器内的ArrayList
中删除城市。但是这些城市仍然保留在您的 SQL 数据库中。然后,当您重新启动 Activity 时,您的 ArrayList 将使用您的 SQL 数据库的数据创建,这些已删除的城市仍然存在。
要始终删除城市,您不仅需要删除适配器中的城市,还需要删除 SQL 数据库中的城市。
【讨论】:
好的。我会试试这个谢谢你 谢谢你的工作以上是关于如何修复 Recyclerview 项目删除显示错误的主要内容,如果未能解决你的问题,请参考以下文章
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