• Chapter 7 example program for Friday, October 25th. Illustrates everything needed for your next project except for the scrollbars. Study Williams College manuscript chapter 7 in conjunction with this example.

1. Chapter 7 - Choice class for pull down lists of choices, for command buttons, option (radio) buttons and Listeners.

2. Here is the Java code...

   import objectdraw.*;
   import java.awt.*;
   import java.awt.event.*;
   
   public class DemoChoice extends WindowController 
                           implements ItemListener, ActionListener
   {
      private Text school;
      private Choice fontSizeChoice;
      private Checkbox panthers, cyclones, hawkeyes;
   
      private Button colorButton, schoolButton;
   
      public void begin()
      {
         school = new Text("UNI Panthers", 50, 100, canvas);
         school.setBold();
         school.setFontSize(32);
   
         fontSizeChoice = new Choice();
   
         fontSizeChoice.add("16");
         fontSizeChoice.add("22");
         fontSizeChoice.add("32");
         fontSizeChoice.add("48");
         fontSizeChoice.add("64");
   
         fontSizeChoice.select("32");
        
         add( fontSizeChoice, BorderLayout.NORTH );
         fontSizeChoice.addItemListener( this );      
   
         colorButton = new Button("Color UNI Panthers");
   
         add( colorButton, BorderLayout.EAST );
         colorButton.addActionListener( this );
   
         addSchoolPanel();
      }
   
      public void itemStateChanged(ItemEvent evt)
      {
         int fontSize;
         
         fontSize = Integer.parseInt( fontSizeChoice.getSelectedItem() );
         school.setFontSize( fontSize );
      }
   
      public void actionPerformed(ActionEvent event)
      {
         if (event.getSource() == colorButton)
         {
            Color c;
            c = school.getColor();
   
            if (c.getRed() > 128)
            {
               school.setColor( Color.blue );
               colorButton.setLabel("Make it RED");
            }
            else
            {
               school.setColor( Color.red );
               colorButton.setLabel("Make it BLUE");
            }
         }
         else if (event.getSource() == schoolButton)
         {
            String t = "";
   
            if (panthers.getState())
               t = "UNI Panthers";
            else if (cyclones.getState())
               t = "ISU Cyclones";
            else if (hawkeyes.getState())
               t = "Iowa Hawkeyes";
   
            school.setText( t );
         }
      }
      
      private void addSchoolPanel()
      {
         Panel radioButtonPanel = new Panel(); 
   
         CheckboxGroup checks = new CheckboxGroup(); 
         panthers = new Checkbox("Panthers", true, checks); 
         cyclones = new Checkbox("Cyclones", false, checks); 
         hawkeyes = new Checkbox("Hawkeyes", false, checks);
    
         radioButtonPanel.add(panthers); 
         radioButtonPanel.add(cyclones); 
         radioButtonPanel.add(hawkeyes);
    
         schoolButton = new Button("Change School Message"); 
         radioButtonPanel.add(schoolButton); 
         add (radioButtonPanel, BorderLayout.SOUTH); 
   
         schoolButton.addActionListener (this); 
      }
   }