Question

我在一个单独的文件中创建了一个类适配器，但在我的主文件中，我调用remove方法来删除项目或我选择的项目，但是当我删除它时，它不会在我的应用程序上更新。

CODE：

public static void populateChatListView(final Context context){
    adapter = new myAdapter(context, R.layout.source_contact);

    listv.setAdapter(adapter);

    for (Contacts friend: friends){
        adapter.add(friend);
    }

    listv.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
        @Override
        public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id) {
            Toast.makeText(context, "DELETED", Toast.LENGTH_SHORT).show();
            //supposed to remove it
            adapter.remove(adapter.getItem(0));
           //supposed to update it(notify)
            adapter.notifyDataSetChanged();
            return true;
        }

    });

    adapter.registerDataSetObserver(new DataSetObserver() {
        @Override
        public void onChanged() {
            super.onChanged();
            listv.setSelection(adapter.getCount() - 1);
        }
    });
}

它没有给我任何错误，也没有删除它。我将不胜感激任何帮助。

CLASS ADAPTER：

public class myAdapter extends ArrayAdapter<Contacts>{
    private List<Contacts> Listc = new ArrayList<>();
    TextView NameWindow, LastN;
    ImageView contactProfile;

    Context context;

    public myAdapter(Context context, int resource) {
        super(context, resource);
        this.context = context;
    }
    @Override
    public void add(Contacts object) {


        Listc.add(object);
        super.add(object);
    }

    @Override
public Contacts getItem(int position) {
    return Listc.get(position);
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    if(convertView == null){
        LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        convertView = inflater.inflate(R.layout.source_contact, parent, false);
    }

    NameWindow = (TextView) convertView.findViewById(R.id.contactN);
    LastN = (TextView) convertView.findViewById(R.id.contactL);

    contactProfile = (ImageView) convertView.findViewById(R.id.contactProfile);

    String name, lastn;

    Contacts provider = getItem(position);

    name = provider.getName(); // name goes down
    lastn = provider.getLastn(); // goes upper

    NameWindow.setText(name);
    LastN.setText(lastMessage);

    return convertView;
}
    ...

编辑。

Answer 1

将此添加到您的适配器类

public void myRemove(int position){
  Listc.remove(position);
  myAdapter.super.notifyDataSetChanged();
}

并使用它来查看它是否会产生影响

Answer 2

我认为在你的适配器中你应该有一个像这样的数组变量。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using System.IO;
using System.Data.SqlClient;

namespace ConsoleApplication1
{
    class Program
    {
        const string FILENAME = @"c:\temp\test.txt";
        enum States
        {
            FIND_OUTPUT,
            GET_SEPERATOR,
            GET_TABLE_HEADER,
            GET_DATA_TABLE,
            END
        }
        static void Main(string[] args)
        {
 
            States state = States.FIND_OUTPUT;
            StreamReader reader = new StreamReader(FILENAME);
            string inputLine = "";

            string connStr = "Enter your connection string here";
            SqlConnection conn = new SqlConnection(connStr);
            conn.Open();
            SqlCommand cmd = new SqlCommand();
            cmd.Connection = conn;

            string[] headers = null;
            while ((inputLine = reader.ReadLine()) != null)
            {
                inputLine = inputLine.Trim();
                if (inputLine.Length > 0)
                {
                    switch (state)
                    {
                        case States.FIND_OUTPUT:
                            if (inputLine.StartsWith("OUTPUT (SQL Server Table)"))
                                state = States.GET_SEPERATOR;
                            break;
                        case States.GET_SEPERATOR:
                            state = States.GET_TABLE_HEADER;
                            break;
                        case States.GET_TABLE_HEADER:
                            headers = inputLine.Split(new char[] { '|'}, StringSplitOptions.RemoveEmptyEntries);
                            headers = headers.Select(x => x.Trim()).ToArray();
                            state = States.GET_DATA_TABLE;
                            break;
                        case States.GET_DATA_TABLE:
                            string[] dataArray = inputLine.Split(new char[] { '|'}, StringSplitOptions.RemoveEmptyEntries);
                            dataArray = dataArray.Select(x => x.Trim()).ToArray();
                            string commandText = string.Format("Insert into table1 ({0}) values ({1})", string.Join(",", headers), "'" + string.Join("','", dataArray) + "'");
                            cmd.CommandText = commandText;    
                            cmd.ExecuteNonQuery();
                            break;
                    }
                }
                else
                {
                    if (state == States.GET_DATA_TABLE)
                        break; //exit while loop if blank row at end of data table
                }
            }

            reader.Close();
            conn.Close();
        }
    }
}

您需要做的就是更新此列表，然后调用

class yourAdapter extends BaseAdapter  {
    private ArrayList<Object> your_list_variable; 
    ....
}

试试吧。

//在这里更新一个例子，你可以查看我的代码。

adapter.notifyDataSetChanged();

希望这对你有所帮助。

Android，它不会从ListView

2 个答案: