Надо дописать програмку на Swing

// SimpleFileChooser.java
// A simple file chooser to see what it takes to make one of these work
//
 
import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;
import java.io.IOException;
import java.util.Arrays;
import java.util.Vector;
 
import javax.swing.JButton;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JOptionPane;
 
public class ListBoxDemo2 extends JFrame {
  final JLabel statusbar = new JLabel(("Output of your selection will go here"), JLabel.CENTER);
  final Vector listContents = new Vector();
  final CheckBoxList checkBoxList = new CheckBoxList();
 
  public ListBoxDemo2() {
    super("ListBoxDemo");
    setSize(400, 300);
    setDefaultCloseOperation(EXIT_ON_CLOSE);
 
    final Container c = getContentPane();
    c.setLayout(new BorderLayout());
    c.add(createPanel1(), BorderLayout.CENTER);
    c.add(createPanel2(), BorderLayout.EAST);
    c.add(createPanel3(), BorderLayout.SOUTH);
 
  }
 
  private JPanel createPanel1() {
    final JPanel panel1 = new JPanel(new BorderLayout());
    final JScrollPane scroll = new JScrollPane(this.checkBoxList);
    scroll.setPreferredSize(new Dimension(350, 300));
    panel1.add(scroll);
    return panel1;
 
  }
 
  private JPanel createPanel2() {
    final JPanel panel2 = new JPanel(new GridLayout(3, 1));
    final JButton addButton = new JButton("Add");
    final JButton deleteButton = new JButton("Remove");
    final JButton openButton = new JButton("Open");
    panel2.add(addButton);
    panel2.add(deleteButton);
    panel2.add(openButton);
    final JPanel p = new JPanel(new BorderLayout());
    p.add(panel2, BorderLayout.NORTH);
 
    addButton.addActionListener(new ActionListener() {
      public void actionPerformed(final ActionEvent ae) {
        final JFileChooser chooser = new JFileChooser();
        chooser.setMultiSelectionEnabled(true);
 
        chooser.addChoosableFileFilter(new SimpleFileFilter(".txt"));
        chooser.setDialogTitle("Please select files to add");
        chooser.setAcceptAllFileFilterUsed(false);
        final File f = new File("Test1");
        chooser.setSelectedFile(f);
 
        final int option = chooser.showOpenDialog(ListBoxDemo2.this);
        if (option == JFileChooser.APPROVE_OPTION) {
          final File[] sf = chooser.getSelectedFiles();
          checkBoxList.setListData(sf );
        } else {
          statusbar.setText("You canceled.");
        }
      }
    });
    deleteButton.addActionListener(new ActionListener() {
      public void actionPerformed(final ActionEvent ae) {
        // get the indices of selected items
        final int select[] = checkBoxList.getSelectedIndices();
        // copy these into a temporary vector
        final Vector v = new Vector();
        for (int i = 0; i < select.length; i++) {
          v.add((checkBoxList.getModel().getElementAt(select[i])));
        }
        // remove from original vector
        for (int i = 0; i < v.size(); i++)
          listContents.remove(v.elementAt(i));
        // reset vector as list source
        checkBoxList.setListData(listContents);
      }
    });
    openButton.addActionListener(new ActionListener(){
    public void actionPerformed(final ActionEvent ae){
        final int select[] = checkBoxList.getSelectedIndices();
       // if (select[0] == 0)
        //{int optionPane = JOptionPane.ERROR_MESSAGE;}
 
    }
    });
    return p;
  }
 
  private JPanel createPanel3() {
    final JPanel panel3 = new JPanel();
    panel3.setLayout(new BorderLayout());
    panel3.setPreferredSize(new Dimension(400, 30));
    panel3.setMinimumSize(new Dimension(100, 30));
 
    panel3.add(statusbar, BorderLayout.SOUTH);
    return panel3;
  }
 
  public static void main(final String args[]) {
    final ListBoxDemo2 sfc = new ListBoxDemo2();
    sfc.setVisible(true);
  }
}

// SimpleFileFilter.java
// A straightforward, extension-based example of a file filter. This should be
// replaced by a "first class" Swing class in a later release of Swing.
//
import javax.swing.filechooser.*;
import java.io.File;
 
public class SimpleFileFilter extends FileFilter {
 
  String[] extensions;
  String description;
 
  public SimpleFileFilter(String ext) {
    this (new String[] {ext}, null);
  }
 
  public SimpleFileFilter(String[] exts, String descr) {
    // Clone and lowercase the extensions
    extensions = new String[exts.length];
    for (int i = exts.length - 1; i >= 0; i--) {
      extensions[i] = exts[i].toLowerCase( );
    }
    // Make sure we have a valid (if simplistic) description.
    description = (descr == null ? exts[0] + " files" : descr);
  }
 
  public boolean accept(File f) {
    // We always allow directories, regardless of their extensions.
    if (f.isDirectory( )) { return true; }
 
    // It's a regular file, so check the extension.
    String name = f.getName( ).toLowerCase( );
    for (int i = extensions.length - 1; i >= 0; i--) {
      if (name.endsWith(extensions[i])) {
        return true;
      }
    }
    return false;
  }
 
  public String getDescription( ) { return description; }
}

import javax.swing.*;
 
public class CheckBoxList extends JList
{
   protected static Border noFocusBorder =
                                 new EmptyBorder(1, 1, 1, 1);
 
   public CheckBoxList()
   {
//      setCellRenderer(new CellRenderer());
//
//      addMouseListener(new MouseAdapter()
//         {
//            public void mousePressed(MouseEvent e)
//            {
//               int index = locationToIndex(e.getPoint());
//
//               if (index != -1) {
//                  JCheckBox checkbox = (JCheckBox)
//                              getModel().getElementAt(index);
//                  checkbox.setSelected(
//                                     !checkbox.isSelected());
//                  repaint();
//               }
//            }
//         }
//      );
 
      setSelectionMode(ListSelectionModel.MULTIPLE_INTERVAL_SELECTION);
   }
 
   protected class CellRenderer implements ListCellRenderer
   {
      public Component getListCellRendererComponent(
                    JList list, Object value, int index,
                    boolean isSelected, boolean cellHasFocus)
      {
      final JCheckBox checkbox = new JCheckBox(String.valueOf(value));
         checkbox.setBackground(isSelected ?
                 getSelectionBackground() : getBackground());
         checkbox.setForeground(isSelected ?
                 getSelectionForeground() : getForeground());
         checkbox.setEnabled(isEnabled());
         checkbox.setFont(getFont());
         checkbox.setFocusPainted(false);
         checkbox.setBorderPainted(true);
         checkbox.setBorder(isSelected ?
          UIManager.getBorder(
           "List.focusCellHighlightBorder") : noFocusBorder);
         return checkbox;
      }
   }
 
 
    
}