import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.DefaultListModel;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JList;
import javax.swing.JScrollPane;
public class Main {
public static final void main(String args[]) throws Exception {
JFrame f = new JFrame();
DefaultListModel<String> dlm = new DefaultListModel<String>();
JList<String> list = new JList<>(dlm);
f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
f.add(new JScrollPane(list));
f.add(new JButton("Add") {
{
addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
dlm.addElement("A");
}
});
}
}, BorderLayout.SOUTH);
f.pack();
f.setVisible(true);
}
}