CS 151 Day 11

Cay S. Horstmann

Day 11 Clicker Question 1

Adding a border to a Swing component is an example of which design pattern?

1. DECORATOR
2. STRATEGY
3. COMPOSITE
4. None of the above

Day 11 Clicker Question 2

In the sample program of Section 5.8, the Bundle class is an example of which design pattern?

1. DECORATOR
2. STRATEGY
3. COMPOSITE
4. None of the above

Day 11 Clicker Question 3

Not everything that is strategic is an instance of the STRATEGY pattern. Which conditions must be fulfilled? Check all that apply.

1. Some method needs to carry a certain task as part of doing its job, but there is more than one way of doing that task.
2. Clients who call the method want to control how that task is executed.
3. An interface is provided with a method for carrying out the task.
4. Clients supply an object whose class implements that interface when calling the method.

Lab

Pattern Discussion

• A Scanner can be used to read numbers and lines from a Reader. Is this an example of the DECORATOR pattern?
• Why or why not?

Which Pattern?

• You can give a title to a border by using the TitledBorder class. For example,

  panel.setBorder(new TitledBorder(new EtchedBorder(),
  "Select one option"));

• Read the Javadoc of the TitledBorder class.
• Which pattern is at work here? Produce a table with the Name in Design Pattern/Actual Name.

HTML Formatting

• Consider the sample program of Section 5.8. Suppose we want to format the invoice in HTML, not plain text. How is this accomplished?
• What design pattern it at work here?
• Does the name of this design pattern seem appropriate in this situation? Why or why not?

Composite Icons

• Use the COMPOSITE pattern to define a class CompositeIcon that implements the Icon interface type and contains a list of icons. Supply a method

  void addIcon(Icon icon)

  . Draw the icons in a horizontal row.
• Demonstrate the class by running

  import javax.swing.*;
  
  public class IconTester
  {
     public static void main(String[] args)
     {
        Icon compositeIcon = new CompositeIcon();
        compositeIcon.addIcon(new MarsIcon(50));
        compositeIcon.addIcon(new ImageIcon("globe.gif"));
        JOptionPane.showMessageDialog(
              null, 
              "Hello, Composite!",
              "Message",
              JOptionPane.INFORMATION_MESSAGE,
              compositeIcon);
        System.exit(0);
     }
  }

Discussion