09. Java GUI Examples (Part 4)

Example 9.3/* Exercise 9.3: Change the example program given in the previous parts to NOT display to System.out,

      but to somewhere in the JFrame (for the display selected button, easier to use a JTextArea).

      In itemStateChanged, display either in the JFrame or in a pop-up window (suggested to try JOptionPane's static method, showMessageDialog).

*/

import javax.swing.JFrame;

public class Exercise_9_3_TryGUIExample

    public static void main(String[] args)

        String [] strs = {"Name", "Company", "Email Address", "Phone"};

        Exercise_9_3_GUIExample gui = new Exercise_9_3_GUIExample(strs);

        gui.setSize(400,300);

        gui.setVisible(true);

        gui.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

Example 9.4

/* Exercise 9.4: Re-do the Java application programs given in Chapter 9, Part I (TryCheckBoxes or FrameProgram ) as awt Applets or swing JApplets

    that display in a GUI window. Run this by choosing a run configuration for Applets.

    To capture the output, type [Alt]-[PrintScreen], then paste in a Word document.

*/

import javax.swing.*;

import java.awt.event.*;

import java.awt.*;

public class Exercise_9_4_TryCheckBoxes_Applets  extends JApplet implements ActionListener

    private JCheckBox chBoxA, chBoxB, chBoxC, chBoxD;

    private JLabel labelA, labelB, labelC, labelD;

    public void init()

        setLayout(new FlowLayout());                // UPDATED!

        chBoxA = new JCheckBox("A");

        chBoxB = new JCheckBox("B");

        chBoxC = new JCheckBox("C");

        chBoxD = new JCheckBox("D");

        chBoxA.addItemListener(new CheckBoxAHandler());

        chBoxB.addItemListener(new CheckBoxBHandler());

        chBoxC.addItemListener(new CheckBoxCHandler());

        chBoxD.addItemListener(new CheckBoxDHandler());

        labelA = new JLabel("A is ON "); labelA.setVisible(false);

        labelB = new JLabel("B is ON "); labelB.setVisible(false);

        labelC = new JLabel("C is ON "); labelC.setVisible(false);

        labelD = new JLabel("D is ON "); labelD.setVisible(false);

        add(chBoxA);

        add(chBoxB);

        add(chBoxC);

        add(chBoxD);

        add(labelA);

        add(labelB);

        add(labelC);

        add(labelD);

    }                     // end init

    public void actionPerformed(ActionEvent e)

        Object source = e.getSource();

        if(source == (Object) chBoxA)

            labelA.setVisible(chBoxA.isSelected());

        else if( source == (Object) chBoxA )

            labelB.setVisible(chBoxA.isSelected());

        } // end actionPerformed

    // inner classes for listener classes

    class CheckBoxAHandler implements ItemListener

        public void itemStateChanged( ItemEvent e )

            if( chBoxA.isSelected() )                                // One way to check if selected

                labelA.setVisible(true);

            else

                labelA.setVisible(false);

        } // end itemStateChanged for check box A

    } // end CheckBoxAHandler listener class

    class CheckBoxBHandler implements ItemListener

        public void itemStateChanged( ItemEvent e )

            if( e.getStateChange() == ItemEvent.SELECTED )             // another way to check if selected

                labelB.setVisible(true);

            else

                labelB.setVisible(false);

        } // end itemStateChanged  for check box B

    } // end CheckBoxBHandler listener class

    class CheckBoxCHandler implements ItemListener

        public void itemStateChanged( ItemEvent e )

            labelC.setVisible(chBoxC.isSelected());                 // BEST WAY

        } // end itemStateChanged for check box C

    } // end CheckBoxCHandler listener class

    class CheckBoxDHandler implements ItemListener

        public void itemStateChanged(ItemEvent e)

            labelD.setVisible(chBoxD.isSelected());