Trying to delete items of a Jlist

Question

I'm trying to dele Items from a Jlist in real-time execution and but I always get a persistent error message the items of the list consist of user names that should be deleted when the server sends a specific message

package com.yorkrider;

import javax.swing.*;
import java.net.*;
import java.io.*;
import java.util.ArrayList;
import java.util.Scanner;
import javax.swing.JOptionPane;

public class A_Chat_Client implements Runnable
{
    // globals
    Socket SOCK;
    Scanner INPUT;
    Scanner SEND = new Scanner(System.in);
    PrintWriter OUT;
    ArrayList<String> Users = new ArrayList<String>();
    // -----------------------------------------------------------------------------------
    public A_Chat_Client(Socket X)
    {
        this.SOCK = X;
    }
    // -----------------------------------------------------------------------------------
    public void run()
    {
        try
        {
            try
            {
                INPUT = new Scanner(SOCK.getInputStream());
                OUT = new PrintWriter(SOCK.getOutputStream());
                OUT.flush();
                CheckStream();
            }
            finally
            {
                SOCK.close();
            }
        }
        catch(Exception X) { System.out.print(X); }
    }
// ---------------------------------------------------------------------------------

    public void DISCONNECT() throws IOException
    {
        OUT.println(A_Chat_Client_GUI.UserName + " has disconnected");
        OUT.flush();
        Remove_User(A_Chat_Client_GUI.UserName, SOCK);
        //SOCK.close();
        JOptionPane.showMessageDialog(null, "You Disconnected");

        //Users.removeAll();
        //System.exit(0);
    }
    // ---------------------------------------------------------------------------------
    public void CheckStream()
    {
        while(true)
        {
            RECEIVE();
            //A_Chat_Client_GUI.JL_ONLINE.setListData(Users)
        }
    }
    // ---------------------------------------------------------------------------------
    public void RECEIVE()
    {
        if(INPUT.hasNext())
        {
            String MESSAGE = INPUT.nextLine();

            if(MESSAGE.contains("#?!"))
            {
                String TEMP1 = MESSAGE.substring(3);
                TEMP1 = TEMP1.replace("[","");
                TEMP1 = TEMP1.replace("]", "");

                String[] CurrentUsers = TEMP1.split(", ");
                A_Chat_Client_GUI.JL_ONLINE.setListData(CurrentUsers);
                //Users.add(TEMP1);

                A_Chat_Client_GUI.TA_CONVERSATION.append(A_Chat_Server.CurrentUsers.get(
                        A_Chat_Server.CurrentUsers.size()-1) +" has joined on IP address "+
                        A_Chat_Client_GUI.HostIP+" and port number "+A_Chat_Client_GUI.PortNumber +"\n");
                A_Chat_Client_GUI.JL_ONLINE.removeAll();
                System.out.println(Users);

            }
//----------------The problem is here-------------------------
            else if(MESSAGE.contains("@!@")) {
                String TEMP1 = MESSAGE.substring(3);
                TEMP1 = TEMP1.replace("[", "");
                TEMP1 = TEMP1.replace("]", "");
                for(int j=0; j < A_Chat_Client_GUI.JL_ONLINE.getModel().getSize(); j++){
                    if (TEMP1.equals(A_Chat_Client_GUI.JL_ONLINE.getModel().getElementAt(j))){
                        A_Chat_Client_GUI.JL_ONLINE.getModel().remove(j);
                    }
                }
            }
//--------------------The problem is here------------------------
            else
            {
                A_Chat_Client_GUI.TA_CONVERSATION.append(MESSAGE + "\n");
            }
        }
    }
// ---------------------------------------------------------------------------------

    public void SEND(String X)
    {
        OUT.println(A_Chat_Client_GUI.UserName + ": " + X);
        OUT.flush();
        A_Chat_Client_GUI.TF_Message.setText("");
    }
// ---------------------------------------------------------------------------------
  
    public static void Remove_User(String UserName, Socket SOCK) throws IOException
    {
        Socket TEMP_SOCK = SOCK;
        PrintWriter OUT = new PrintWriter(TEMP_SOCK.getOutputStream());
        OUT.println("@!@" + UserName);
        System.out.println(UserName);
        OUT.flush();
    }
   
}

That is the error message that is the persistent error message:

java.lang.ArrayIndexOutOfBoundsException: Array index out of range: 0

Answer 1

I can't understand your code without the implementation of your classes, but perhaps you need:

A_Chat_Client_GUI.JL_ONLINE.getModel().remove(j);

instead of:

A_Chat_Client_GUI.JL_ONLINE.remove(j);

The loop for should start from the last index:

for (int j = A_Chat_Client_GUI.JL_ONLINE.getModel().getSize() - 1; j >= 0; j--) {
    if (TEMP1.equals(A_Chat_Client_GUI.JL_ONLINE.getModel().getElementAt(j))) {
        A_Chat_Client_GUI.JL_ONLINE.getModel().remove(j);
    }
}

This way, non scanned indexes stay at the same place (keep same index j ) after any remove.