我想从列表视图中删除项目而不重新启动活动

Question

我想通过长按列表视图项目来删除该项目。删除项目后，我需要重新启动 activity 才能看到更改，但我想立即看到更改

我已经尝试过 notifyDataSetChanged();但它不起作用我从sqlite数据库中获取数据并将其放入哈希图中并将其发送到自定义适配器长按从数据库中删除一行，但列表视图中没有发生任何更改。

@Override
public View getView( final  int position, View convertView, ViewGroup parent) {
    View view = super.getView(position, convertView, parent);
    ImageView imageView = view.findViewById(R.id.detailsimage);
    CardView cardView = view.findViewById(R.id.detailcardView);
    TextView textmo =view.findViewById(R.id.detailsmo);
    TextView texttu =view.findViewById(R.id.detailstu);
    TextView textwe =view.findViewById(R.id.detailswe);
    TextView textth =view.findViewById(R.id.detailsthu);
    TextView  textfr =view.findViewById(R.id.detailsfri);
    TextView textsa =view.findViewById(R.id.detailssat);
    TextView textsu =view.findViewById(R.id.detailssun);

    final databasehandler db = new databasehandler(context);
    cardView.setOnLongClickListener(new View.OnLongClickListener() {
        @Override
        public boolean onLongClick(View v) {

            db.deleteTitle(position+1);
            Toast.makeText(context,Integer.toString(position),Toast.LENGTH_SHORT).show();
            notifyDataSetChanged();

            return true;
        }
    });

    imageView.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            HashMap<String, String> hashmap= arrayList.get(position);
            String string= hashmap.get("repeat");
            string = Objects.requireNonNull(string).trim();


            Toast.makeText(context,string,Toast.LENGTH_SHORT).show();
        }
    });

    HashMap<String, String> hashmap= arrayList.get(position);
    String string= Objects.requireNonNull(hashmap.get("repeat")).trim();
   String[] separated = Objects.requireNonNull(string).split("");

                        }
            }}
 return view;
 }
}

Answer 1

将列表传递到适配器并更改此块

cardView.setOnLongClickListener(new View.OnLongClickListener() {
    @Override
    public boolean onLongClick(View v) {

        db.deleteTitle(position+1);
        yourList.remove(position);
     Toast.makeText(context,Integer.toString(position),Toast.LENGTH_SHORT).show();
        notifyDataSetChanged();

        return true;
    }
});

Answer 2

好吧，您应该在自定义适配器中重新加载数据。根据您的描述，我了解到它不以任何方式与数据库绑定，所以您为什么期望它在调用 notifyDataSetChange() 后重新加载？ notifyDataSetChange 当您在适配器中注册了实际的观察者时才有效。

查看 Loaders 和 Content Providers 以便在您的 ListView 中自动反映数据库状态。这是 link - https://developer.android.com/guide/components/loaders

Answer 3

你不应该调用notifyDataSetChanged它会刷新整个列表，这会影响性能

cardView.setOnLongClickListener(new View.OnLongClickListener() {
    @Override
    public boolean onLongClick(View v) {
        db.deleteTitle(position+1);
        yourArrayList.remove(position);
        Toast.makeText(context,Integer.toString(position),Toast.LENGTH_SHORT).show();
        notifyItemRemoved(position);
        return true;
    }
});

Answer 4

请创建自定义数组列表：-

List<Integer> al = new ArrayList<>(); 
    al.add("item 1"); 
    al.add("item 2"); 
    al.add("item 3"); 
    al.add("item 4"); 
    al.add("item 5");

设置适配器：-

StableArrayAdapter adapter = new StableArrayAdapter(this,
            android.R.layout.simple_list_item_1, a1);
    listview.setAdapter(adapter);

从位置删除项目

al.remove(position);

现在刷新列表视图适配器：-

adapter.notifyDataSetChanged();

我想从列表视图中删除项目而不重新启动活动

i want to delete item from listview without restarting actitvity

android

listview

baseadapter