Algorithms and Programming

import java.awt.*; import java.awt.event.*; import javax.swing.*; public class Exam3 extends JApplet implements ActionListener { // Text fields for Number 1, Number 2, and Result private JTextField jtfNum1, jtfNum2, jtfResult; // Buttons "Add", "Subtract", "Multiply" and "Divide" private JButton jbtAdd, jbtSub, jbtMul, jbtDiv; // Menu items "Add", "Subtract", "Multiply","Divide" and "Close" private JMenuItem jmiAdd, jmiSub, jmiMul, jmiDiv, jmiClose; private JPopupMenu jPopupMenu1 = new JPopupMenu(); public Exam3() { // Create menu bar JMenuBar jmb = new JMenuBar(); // Set menu bar to the frame setJMenuBar(jmb); // Add menu "Operation" to menu bar JMenu operationMenu = new JMenu("Operation"); operationMenu.setMnemonic('O'); jmb.add(operationMenu); // Add menu "Exit" in menu bar JMenu exitMenu = new JMenu("Exit"); exitMenu.setMnemonic('E'); jmb.add(exitMenu); // Add menu items with mnemonics to menu "Operation" operationMenu.add(jmiAdd= new JMenuItem("Add", 'A')); operationMenu.add(jmiSub = new JMenuItem("Subtract", 'S')); operationMenu.add(jmiMul = new JMenuItem("Multiply", 'M')); operationMenu.add(jmiDiv = new JMenuItem("Divide", 'D')); exitMenu.add(jmiClose = new JMenuItem("Close", 'C')); // Set keyboard accelerators jmiAdd.setAccelerator( KeyStroke.getKeyStroke(KeyEvent.VK_A, jmiSub.setAccelerator( KeyStroke.getKeyStroke(KeyEvent.VK_S, jmiMul.setAccelerator( KeyStroke.getKeyStroke(KeyEvent.VK_M, jmiDiv.setAccelerator( KeyStroke.getKeyStroke(KeyEvent.VK_D, ActionEvent.CTRL_MASK)); ActionEvent.CTRL_MASK)); ActionEvent.CTRL_MASK)); ActionEvent.CTRL_MASK)); // Panel p1 to hold text fields and labels JPanel p1 = new JPanel(); p1.setLayout(new FlowLayout()); p1.add(new JLabel("Number 1")); p1.add(jtfNum1 = new JTextField(3)); p1.add(new JLabel("Number 2")); p1.add(jtfNum2 = new JTextField(3)); p1.add(new JLabel("Result")); p1.add(jtfResult = new JTextField(4)); jtfResult.setEditable(false); // Panel p2 to hold buttons JPanel p2 = new JPanel(); p2.setLayout(new FlowLayout()); p2.add(jbtAdd p2.add(jbtSub p2.add(jbtMul p2.add(jbtDiv = = = = new new new new JButton("Add")); JButton("Subtract")); JButton("Multiply")); JButton("Divide")); // Add panels to the frame getContentPane().setLayout(new BorderLayout()); getContentPane().add(p1, BorderLayout.CENTER); getContentPane().add(p2, BorderLayout.SOUTH); // Register listeners jbtAdd.addActionListener(this); jbtSub.addActionListener(this); jbtMul.addActionListener(this); jbtDiv.addActionListener(this); jmiAdd.addActionListener(this); jmiSub.addActionListener(this); jmiMul.addActionListener(this); jmiDiv.addActionListener(this); jmiClose.addActionListener(this); // Add menu "Operation" to menu bar JMenu operationMenu1 = new JMenu("Operation"); operationMenu1.setMnemonic('O'); jmb.add(operationMenu1); // Add menu "Exit" in menu bar JMenu exitMenu1 = new JMenu("Exit"); exitMenu.setMnemonic('E'); jmb.add(exitMenu1); // Add menu items with mnemonics to menu "Operation" operationMenu1.add( new JMenuItem("Add", 'A')); operationMenu1.add( new JMenuItem("Subtract", 'S')); operationMenu1.add(new JMenuItem("Multiply", 'M')); operationMenu1.add(new JMenuItem("Divide", 'D')); exitMenu1.add(new JMenuItem("Close", 'C')); jPopupMenu1.add(operationMenu1); jPopupMenu1.add(exitMenu1); p1.addMouseListener(new MouseAdapter() { public void mousePressed(MouseEvent e) { // For Motif showPopup(e); } } public void mouseReleased(MouseEvent e) { // For Windows showPopup(e); } }); /** Handle ActionEvent from buttons and menu items */ public void actionPerformed(ActionEvent e) { String actionCommand = e.getActionCommand(); // Handle button events if (e.getSource() instanceof JButton) { if ("Add".equals(actionCommand)) calculate('+'); else if ("Subtract".equals(actionCommand)) calculate('-'); else if ("Multiply".equals(actionCommand)) calculate('*'); else if ("Divide".equals(actionCommand)) calculate('/'); } } else if (e.getSource() instanceof JMenuItem) { // Handle menu item events if ("Add".equals(actionCommand)) calculate('+'); else if ("Subtract".equals(actionCommand)) calculate('-'); else if ("Multiply".equals(actionCommand)) calculate('*'); else if ("Divide".equals(actionCommand)) calculate('/'); else if ("Close".equals(actionCommand)) System.exit(0); } /** Calculate and show the result in jtfResult */ private void calculate(char operator) { // Obtain Number 1 and Number 2 int num1 = (Integer.parseInt(jtfNum1.getText().trim())); int num2 = (Integer.parseInt(jtfNum2.getText().trim())); int result = 0; // Perform selected operation switch (operator) { case '+': result = num1 + num2; break; case '-': result = num1 - num2; break; case '*': result = num1 * num2; break; case '/': result = num1 / num2; } } // Set result in jtfResult jtfResult.setText(String.valueOf(result)); /** Display popup menu when triggered */ private void showPopup(java.awt.event.MouseEvent evt) { if (evt.isPopupTrigger()) jPopupMenu1.show(evt.getComponent(), evt.getX(), evt.getY()); } } public static void main(String[] args) { Exam3 applet = new Exam3(); JFrame frame = new JFrame(); //EXIT_ON_CLOSE == 3 frame.setDefaultCloseOperation(3); frame.setTitle("Exam3"); frame.getContentPane().add(applet, BorderLayout.CENTER); applet.init(); applet.start(); frame.setSize(400,320); Dimension d = Toolkit.getDefaultToolkit().getScreenSize(); frame.setLocation((d.width - frame.getSize().width) / 2, (d.height - frame.getSize().height) / 2); frame.setVisible(true); }