Class 16: Lab: Java's AWT, Continued

Held Wednesday, September 20, 2000

Summary

Today we continue our exploration of the AWT by considering issues involved with laying out interfaces.

Notes

• Are there any final questions on exam 1?
  • I've fixed an error in the code for simplify. Thanks to those of you who caught it.
• I should be in my office until about 2:45 today and much of the day tomorrow.
• We'll talk about the project on Friday.

Overview

Other Java GUI Strategies

• It turns out there are many different ways to write similar GUIs.
• You've already seen two alternatives for writing listeners and their accompanying handlers.
  • Create a separate class.
  • Create an anonymous class.
• There are also many different places to put the Frame.
  • We made it a variable in main. In general, that's not the best idea.
  • We could have an object (in a new class) responsible for creating the Frame.
  • We could have an object in a new class that extends Frame.
• I'll admit no strong preference, except that separate classes seem to be your best bet.

Filling in Labels

• Let's create a simple application that greets the user.
• We need a text field for the user's name.
• We need a label for instructions (and perhaps the result).
• We need a button for "Hi!"
• We can get the text in the field with getText()
• We can set the text in the label with setText(new text)

Designing the GUI

• As many of you have noted, the arrangement of our GUIs leaves something to be desired.
• The AWT is designed for building fairly generic GUIs.
  • There may also be an implicit assumption that you'll use a GUI design tool to build the code for your GUI.
• Most components resize themselves to fit the available area.
• So how do you get better GUIs?
  • Use a design tool.
  • Use grid layouts and panels.
• We'll look at the second technique.
• java.awt.GridLayout lets you set up an NxM grid of areas in which you can put components.
• java.awt.Panel is a blank slate that you can add a grid layout to.
• Let's draw some pictures and think about how to create them.