Library class

import java.util.ArrayList;import java.awt.*;import java.awt.event.*;import javax.swing.*;/** * The library class. The library class is made and books and other * items are added to it. *  * Student name - Shane Donohoe * Student ID - 06009979 * Date - 9th April 2007 */public class Library extends JFrame{    private ArrayList<Book> books;    private Container mainContainer;    private JButton searchButton;    private JButton addButton;    private JButton borrowButton;    private JButton returnButton;    private JTextField bookField;    private JTextField borrowerField;    private JLabel bookLabel;    private JLabel borrowerLabel;    private Book Bookentry;    private JFrame errorPane;    public Library()    {        super("Library catalogue");        books = new ArrayList<Book>();        mainContainer = getContentPane();        mainContainer.setLayout(new GridLayout(0,1));        JPanel panel1 = new JPanel();        JPanel panel2 = new JPanel();        JPanel panel3 = new JPanel();        mainContainer.add(panel1);        mainContainer.add(panel2);        mainContainer.add(panel3);        bookField = new JTextField("",20);        borrowerField = new JTextField("",20);        bookLabel = new JLabel("Enter book description here");        borrowerLabel = new JLabel("Enter borrower ID here");        searchButton = new JButton("Search");        searchButtonHandler searchHandler = new searchButtonHandler();        searchButton.addActionListener(searchHandler);        addButton = new JButton("Add");        addButtonHandler addHandler = new addButtonHandler();        addButton.addActionListener(addHandler);        borrowButton = new JButton("Borrow");        returnButton = new JButton("Return");        panel1.add(bookLabel);        panel1.add(bookField);        panel2.add(borrowerLabel);        panel2.add(borrowerField);        panel3.add(addButton);        panel3.add(searchButton);        panel3.add(borrowButton);        panel3.add(returnButton);        setSize(350, 300);        setVisible(true);    }        private class addButtonHandler implements ActionListener    {        public void actionPerformed(ActionEvent event)        {            addBook();        }    }        private class searchButtonHandler implements ActionListener    {        public void actionPerformed(ActionEvent event)        {            searchBook();        }    }        public void addBook()    {        String borrowerEntry = borrowerField.getText();        if (borrowerEntry.length() > 0)        {            JOptionPane.showMessageDialog(errorPane, "Please leave the borrower field blank when adding a book");        }        else        {            String newBook = bookField.getText();            Bookentry = new Book(newBook);            books.add(Bookentry);        }    }        public void searchBook()    {        String borrowerEntry = borrowerField.getText();        String bookEntry = bookField.getText();        if (borrowerEntry.length() == 0 && bookEntry.length() == 0)        {            for(Book book : books)            {                book.print();            }        }        else if (borrowerEntry.length() == 0 && bookEntry.length() > 0)        {                    }    }        //public void addBorrower()    //{    //    String borrowerEntry = borrowerField.getText();    //    String bookEntry = bookfield.getText();                        }