Main.java Source code

Introduction

Here is the source code for Main.java

Source

import java.awt.BorderLayout;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.BorderFactory;
import javax.swing.Box;
import javax.swing.BoxLayout;
import javax.swing.DefaultListModel;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JList;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JSeparator;
import javax.swing.JTextField;
import javax.swing.ListSelectionModel;
import javax.swing.SwingConstants;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;
import javax.swing.event.ListSelectionEvent;
import javax.swing.event.ListSelectionListener;

public class Main extends JPanel implements ListSelectionListener {
    JList list;
    DefaultListModel listModel = new DefaultListModel();
    static final String addCommand = "Add";
    static final String deleteCommand = "Delete";
    JButton fireButton;
    JTextField employeeName;

    public Main() {
        super(new BorderLayout());
        listModel.addElement("A");
        listModel.addElement("B");
        listModel.addElement("C");

        list = new JList(listModel);
        list.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
        list.setSelectedIndex(0);
        list.addListSelectionListener(this);
        list.setVisibleRowCount(5);
        JScrollPane listScrollPane = new JScrollPane(list);

        JButton hireButton = new JButton(addCommand);
        HireListener hireListener = new HireListener(hireButton);
        hireButton.setActionCommand(addCommand);
        hireButton.addActionListener(hireListener);
        hireButton.setEnabled(false);

        fireButton = new JButton(deleteCommand);
        fireButton.setActionCommand(deleteCommand);
        fireButton.addActionListener(new FireListener());

        employeeName = new JTextField(10);
        employeeName.addActionListener(hireListener);
        employeeName.getDocument().addDocumentListener(hireListener);
        String name = listModel.getElementAt(list.getSelectedIndex()).toString();
        System.out.println(name);

        // Create a panel that uses BoxLayout.
        JPanel buttonPane = new JPanel();
        buttonPane.setLayout(new BoxLayout(buttonPane, BoxLayout.LINE_AXIS));
        buttonPane.add(fireButton);
        buttonPane.add(Box.createHorizontalStrut(5));
        buttonPane.add(new JSeparator(SwingConstants.VERTICAL));
        buttonPane.add(Box.createHorizontalStrut(5));
        buttonPane.add(employeeName);
        buttonPane.add(hireButton);
        buttonPane.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));

        add(listScrollPane, BorderLayout.CENTER);
        add(buttonPane, BorderLayout.PAGE_END);
    }

    class FireListener implements ActionListener {

        public void actionPerformed(ActionEvent e) {
            int index = list.getSelectedIndex();
            listModel.remove(index);
            int size = listModel.getSize();
            if (size == 0) { // Nobody's left, disable firing.
                fireButton.setEnabled(false);
            } else { // Select an index.
                if (index == listModel.getSize()) {
                    // removed item in last position
                    index--;
                }
                list.setSelectedIndex(index);
                list.ensureIndexIsVisible(index);
            }
        }
    }

    class HireListener implements ActionListener, DocumentListener {
        boolean alreadyEnabled = false;
        JButton button;

        public HireListener(JButton button) {
            this.button = button;
        }

        public void actionPerformed(ActionEvent e) {
            String name = employeeName.getText();
            if (name.equals("") || alreadyInList(name)) {
                Toolkit.getDefaultToolkit().beep();
                employeeName.requestFocusInWindow();
                employeeName.selectAll();
                return;
            }

            int index = list.getSelectedIndex();
            if (index == -1) { // no selection, so insert at beginning
                index = 0;
            } else { // add after the selected item
                index++;
            }

            listModel.insertElementAt(employeeName.getText(), index);
            employeeName.requestFocusInWindow();
            employeeName.setText("");
            list.setSelectedIndex(index);
            list.ensureIndexIsVisible(index);
        }

        protected boolean alreadyInList(String name) {
            return listModel.contains(name);
        }

        public void insertUpdate(DocumentEvent e) {
            enableButton();
        }

        public void removeUpdate(DocumentEvent e) {
            handleEmptyTextField(e);
        }

        public void changedUpdate(DocumentEvent e) {
            if (!handleEmptyTextField(e)) {
                enableButton();
            }
        }

        private void enableButton() {
            if (!alreadyEnabled) {
                button.setEnabled(true);
            }
        }

        private boolean handleEmptyTextField(DocumentEvent e) {
            if (e.getDocument().getLength() <= 0) {
                button.setEnabled(false);
                alreadyEnabled = false;
                return true;
            }
            return false;
        }
    }

    public void valueChanged(ListSelectionEvent e) {
        if (e.getValueIsAdjusting() == false) {
            if (list.getSelectedIndex() == -1) {
                fireButton.setEnabled(false);
            } else {
                fireButton.setEnabled(true);
            }
        }
    }

    public static void main(String[] args) {
        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JComponent newContentPane = new Main();
        newContentPane.setOpaque(true);
        frame.setContentPane(newContentPane);
        frame.pack();
        frame.setVisible(true);
    }
}