JFC 2

1
JFC 2

• Revenge of the Swing

2
More Input, Please

• What about creating large text areas for typing
  in descriptions, notes, etc? Or, for displaying
  large sections of text?
• Enter the JTextArea widget
• See TextAreaWidget.java

3
Custom Cell Rendering

• How can we change the color, font, etc of items
  that are displayed in a list? This is handled by
  another STRATEGY pattern object in swing, called
  the ListCellRenderer. The Cell Renderer is a
  class that tells the entries in the list how to
  format themselves
• See CellRender.java

4
May I see the menu?

• In my discussion of the JFrame container, I
  mentioned that among other things, it can contain
  a Menu bar. How, precisely, do we get this menu
  bar in place, and how do we make it work?
• See MenuBarDemo.java

5
Check Please!

• JCheckBox is another handy widget to get user
  input.
• Although it is a button, and thus inherits the
  buttons ability to be clicked, it is primarily
  used in conjunction with another button or input
  method, like the text box.
• See CheckBoxDemo.java

6
Graphical Alerts

• How do you relay errors to the user in a GUI
  system?
• You could have a text area that lists out status
  messages, but this takes up real estate, and is
  usually ugly.
• The most common method is to pop up an error
  dialog.
• See DialogDemo.java

7
Lets see some progress

• Sometimes, a program will need to perform
  operations that are very time consuming.
• Users hate waiting more than .02 seconds for
  anything to happen
• Sometimes, the distraction of a pretty graphic
  letting them know that its working solves the
  problem.
• See ProgressBarDemo.java

8
The raw deal

• So far, we have looked at some of the swing
  toolkits many pre-defined widgets for creating
  graphical user interfaces.
• Sooner or later, you will want to do something
  that doesnt have a widget
• Java also allows you to draw your own widgets, by
  using the graphics primitives.

9
Where do I draw?

• Theoretically, you can override the paint method
  of any component. This is a very bad idea,
  unless you know exactly what you are doing.
  Since you are creating a new component of your
  very own, you want to start at the base of the
  swing object hierarchy, with a JComponent.

10
How do I draw?

• Override the PaintComponent(Graphics g) method,
  and go to town.
• See DrawDemo.java

11
Wow, that was lame.

• True. Most components that you are going to
  create yourself will have more complicated
  behavior than just drawing some shapes and
  calling it quits. Often this behavior will
  depend on user input. So, how do you capture
  user input in a GUI?
• The mouse, silly.
• See DrawDemo2.java