Ragazzi quello che vi posto è un semplicissimo programma che comprende: Un campo di testo una JList e un bottone.

Al click sul bottone, il contenuto della casella di testo dovrebbe essere aggiunto alla Jlist ma purtroppo non succede niente.

codice:
 

import java.awt.BorderLayout; 

import javax.swing.DefaultListModel; 
import javax.swing.JPanel; 
import javax.swing.JFrame; 
import javax.swing.JButton; 
import java.awt.Rectangle; 
import javax.swing.JScrollPane; 
import javax.swing.JList; 
import java.awt.Dimension; 
import javax.swing.JTextField; 

public class List extends JFrame { 

    private static final long serialVersionUID = 1L; 
    private JPanel jContentPane = null; 
    private JButton jButton = null; 
    private JScrollPane jScrollPane = null; 
    private JList jList = null; 
    private DefaultListModel listModel = null; 
    private JTextField jTextField = null; 

    public List() { 
        super(); 
        initialize(); 
    } 
    private void initialize() { 
        this.setSize(300, 232); 
        this.setContentPane(getJContentPane()); 
        this.setTitle("JFrame"); 
    } 
    private JPanel getJContentPane() { 
        if (jContentPane == null) { 
            jContentPane = new JPanel(); 
            jContentPane.setLayout(null); 
            jContentPane.add(getJButton(), null); 
            jContentPane.add(getJScrollPane(), null); 
            jContentPane.add(getJTextField(), null); 
        } 
        return jContentPane; 
    } 
    private JButton getJButton() { 
        if (jButton == null) { 
            jButton = new JButton(); 
            jButton.setBounds(new Rectangle(63, 148, 162, 37)); 
            jButton.addActionListener(new java.awt.event.ActionListener() { 
                public void actionPerformed(java.awt.event.ActionEvent e) { 
                    listModel = new DefaultListModel(); 
                    listModel.addElement(jTextField.getText()); 
                    jList = new JList(listModel); 
                } 
            }); 
        } 
        return jButton; 
    } 
    private JScrollPane getJScrollPane() { 
        if (jScrollPane == null) { 
            jScrollPane = new JScrollPane(); 
            jScrollPane.setBounds(new Rectangle(62, 46, 165, 92)); 
            jScrollPane.setViewportView(getJList()); 
        } 
        return jScrollPane; 
    } 
    private JList getJList() { 
        if (jList == null) { 
            jList = new JList(); 
            jList.setModel(new DefaultListModel()); 
            jList.setVisibleRowCount(-1); 
        } 
        return jList; 
    } 
    private JTextField getJTextField() { 
        if (jTextField == null) { 
            jTextField = new JTextField(); 
            jTextField.setBounds(new Rectangle(62, 4, 164, 33)); 
        } 
        return jTextField; 
    } 
}