How to reset JList?

how to clear all items inside a JList?

I have tried using

trackList.removeAll(()

but does no effect.

I also tried using code below:

Object[] blank = {""};
trackList.setListData(blank);

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

Thanks & regards


isuhendroAsked:
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ADSLMarkCommented:
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.setSize(640,480);
        this.setLayout(new FlowLayout());
        this.setTitle("List Example");
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        this.num = 1;

        this.model = new DefaultListModel();

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

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

        this.list = new JList(model);

        this.add(list);
        this.add(butAdd);
        this.add(butClear);
    }

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

Mark
0

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ADSLMarkCommented:
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().

Mark
0
isuhendroAuthor Commented:
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..
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ADSLMarkCommented:
Well, then you are bound to the solution you mentioned:

this.data = new String[]{};
this.list.setListData(this.data);

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.

Mark
0
isuhendroAuthor Commented:
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.
0
ADSLMarkCommented:
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. :-)

Mark
0
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