Tài liệu Java lập trình

package de_tai;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.util.ArrayList;
import javax.swing.*;
public class Main extends JFrame implements ActionListener, MouseListener
{
private JList jlist;
private JLabel jlabel;
private JTextField jtextfield;
private JButton jbtnthem, jbtnxoa, jbtnsua, jbtntinh;
private ArrayList<Object> arr;
int index = -1;
JScrollPane js;
public Main()
{
arr = new ArrayList<Object>();
this.setLayout(null);
jlist = new JList(arr.toArray());
js = new JScrollPane(jlist);
js.setLocation(20, 20);
js.setSize(100, 300);
jlabel = new JLabel(Nhap lieu: );
jlabel.setLocation(130, 20);
jlabel.setSize(80, 30);
jtextfield = new JTextField();
jtextfield.setSize(200, 30);
jtextfield.setLocation(200, 20);
jbtnthem = new JButton(Them);
jbtnthem.setSize(100, 50);
jbtnthem.setLocation(200, 80);
jbtnxoa = new JButton(Xoa);
jbtnxoa.setSize(100, 50);
jbtnxoa.setLocation(200, 140);
jbtnxoa.setEnabled(false);
jbtnsua = new JButton(Sua);
jbtnsua.setSize(100, 50);
jbtnsua.setLocation(200, 200);
jbtnsua.setEnabled(false);
jbtntinh = new JButton(Tinh);
jbtntinh.setSize(100, 50);
jbtntinh.setLocation(200, 260);
jbtntinh.setEnabled(false);
this.add(js);
this.add(jlabel);
this.add(jtextfield);
this.add(jbtnthem);
this.add(jbtnxoa);
this.add(jbtnsua);
this.add(jbtntinh);
jbtnthem.addActionListener(this);
jbtnxoa.addActionListener(this);
jbtnsua.addActionListener(this);
jbtntinh.addActionListener(this);
jlist.addMouseListener(this);
}
public static void main(String[] args)
{
Main frame = new Main();
frame.setTitle(De Tai);
frame.setSize(435, 400);
frame.setLocationRelativeTo(null);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
frame.setResizable(false);
}

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// public void valueChanged(ListSelectionEvent e)
// {
// index = jlist.getSelectedIndex();
// if (index != -1)
// {
// jtextfield.setText(arr.get(index).toString());
// //JOptionPane.showMessageDialog(this, index);
// }
// }
public void mouseClicked(MouseEvent e) {
//throw new UnsupportedOperationException(Not supported yet.);
}
public void mousePressed(MouseEvent e) {
if (e.getButton() == MouseEvent.BUTTON1)
{
index = jlist.getSelectedIndex();
if (index != -1)
{
jtextfield.setText(arr.get(index).toString());
//JOptionPane.showMessageDialog(this, index);
}
if(jlist.getSelectedValue() != null)
{
jbtnsua.setEnabled(true);
jbtnxoa.setEnabled(true);
}
// else
// {
// jbtnsua.setEnabled(false);
// jbtnxoa.setEnabled(false);
// }
}
}
public void mouseReleased(MouseEvent e) {
// throw new UnsupportedOperationException(Not supported yet.);
}
public void mouseEntered(MouseEvent e) {
//throw new UnsupportedOperationException(Not supported yet.);
}
public void mouseExited(MouseEvent e) {
//throw new UnsupportedOperationException(Not supported yet.);
}
}