How to reset JList?

Posted on 2007-03-31
Last Modified: 2008-02-01
how to clear all items inside a JList?

I have tried using


but does no effect.

I also tried using code below:

Object[] blank = {""};

.. it will clear up, but change this list as if setVisibleRowCount = 1.

Thanks & regards

Question by:isuhendro
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 4
  • 2
LVL 10

Accepted Solution

ADSLMark earned 125 total points
ID: 18828619
Here is an example application of JList (hand-made!):

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class Listing
    extends JFrame
    implements ActionListener
    private JButton butAdd;
    private JButton butClear;
    private JList list;
    private DefaultListModel model;
    private int num;

    public Listing()
        this.setLayout(new FlowLayout());
        this.setTitle("List Example");

        this.num = 1;

        this.model = new DefaultListModel();

        this.butClear = new JButton("Clear!");

        this.butAdd = new JButton("Add");

        this.list = new JList(model);


    public void actionPerformed(ActionEvent ae)
        if(ae.getSource() == this.butClear)
        else if(ae.getSource() == this.butAdd)
            this.model.add(this.model.getSize(),"Track "+this.num);

    public static void main(String[] args)
        new Listing().setVisible(true);

As you can see, it works with a DefaultListModel, where you have a clear() method to clear the list.

LVL 10

Expert Comment

ID: 18828621
I also have a probable cause of your problem, the GUI doesn't get updated after a "removeAll()", so maybe all the elements are removed, but the GUI doesn't know yet. It might work if you do a repaint().


Author Comment

ID: 18828727
hello Mark,

thanks for your reply. I prefer not to using model for this JList, otherwise will need to change codes at other part.

btw repaint() will not help as well..
What does it mean to be "Always On"?

Is your cloud always on? With an Always On cloud you won't have to worry about downtime for maintenance or software application code updates, ensuring that your bottom line isn't affected.

LVL 10

Assisted Solution

ADSLMark earned 125 total points
ID: 18828754
Well, then you are bound to the solution you mentioned: = new String[]{};

Set the list data to be empty. Don't forget to also set your real data holder (if it's an attribute of your class) to empty, otherwise when you reuse the variable to reset the listdata, it will still contain the old values.


Author Comment

ID: 18830731
ok then Mark... just found out that the problem with setVisibleCountRow become 1, is related to the BorderLayout... not to the list itself.. so i will use previous solution. Btw what is the advantage of using DefaultListModel ?
Thanks & regards.
LVL 10

Expert Comment

ID: 18831254
Better design, more functionality for free.
Take a look at the model-view-controller design pattern. You have one model with maybe multiple views and multiple controllers. This way the model/view/controller are separated from each other which makes extending it easy etc.
Many advantages by using established design patterns.. anyway, it's not necessary. :-)


Featured Post

On Demand Webinar: Networking for the Cloud Era

Did you know SD-WANs can improve network connectivity? Check out this webinar to learn how an SD-WAN simplified, one-click tool can help you migrate and manage data in the cloud.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

An old method to applying the Singleton pattern in your Java code is to check if a static instance, defined in the same class that needs to be instantiated once and only once, is null and then create a new instance; otherwise, the pre-existing insta…
In this post we will learn different types of Android Layout and some basics of an Android App.
Viewers will learn about arithmetic and Boolean expressions in Java and the logical operators used to create Boolean expressions. We will cover the symbols used for arithmetic expressions and define each logical operator and how to use them in Boole…
Viewers will learn one way to get user input in Java. Introduce the Scanner object: Declare the variable that stores the user input: An example prompting the user for input: Methods you need to invoke in order to properly get  user input:

622 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question