从JList中删除项目

Question

here is a code , I want to change JList items, but when i click on open button and JList.removeAll() runs , my JList doesn't remove items... what is the problem?

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


public class JListTest {
    public static void main(String[] args) {
        String[] j = {"item1","item2","item3"};
        final JList list = new JList(j);

        JButton open = new JButton("open");
        open.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                list.removeAll();
            }
        });

        JFrame frame = new JFrame();
        frame.setSize(400, 400);
        Container con = frame.getContentPane();
        con.setLayout(new BorderLayout());
        con.add(open,BorderLayout.LINE_START);
        con.add(list,BorderLayout.CENTER);
        con.add(new JScrollPane(list));
        frame.setVisible(true);
    }
}

if you don't believe that , please test.

Answer 1

The way you do it is wrong. With your constructor new JList(j) there is only a "read- only model".

http://docs.oracle.com/javase/7/docs/api/javax/swing/JList.html It's easy to display an array or Vector of objects, using the JList constructor that automatically builds a read-only ListModel instance for you:

You should use a real Model for it like:

public class JListTest {


public static void main(String[] args) {

    DefaultListModel<String> model = new DefaultListModel<>();
    model.addElement("item1");
    model.addElement("item2");
    model.addElement("item3");
    final JList<String> list = new JList<String>(model);

    JButton open = new JButton("open");
    open.addActionListener(new ActionListener()

    {
        public void actionPerformed(ActionEvent e) {
            DefaultListModel<String> model = (DefaultListModel<String>) list.getModel();
            model.removeAllElements();
        }
    });
    JFrame frame = new JFrame();
    frame.setSize(400, 400);
    Container con = frame.getContentPane();
    con.setLayout(new BorderLayout());

    con.add(open, BorderLayout.LINE_START);
    con.add(list, BorderLayout.CENTER);
    con.add(new JScrollPane(list));
    frame.setVisible(true);

}

}