Fundamentals of the AWT

Applets:

• not use frames
• not use menus

If you do use menus/frames(i.e for a pop-up menu), then you must live with the "untrusted window" message. More importantly, Frames/Dialogs can to ill-behaving and not close if you do not handle the Event.WINDOW_DESTROY message.

But.. we will start with applications first of all, because of fewer restriction. Although I will try not to provide information too specific to stand-alone applications. The first few sections are not particularly useful for applet writers, but later sections rely on concepts learnt early on.

Structure of the AWT

• Containers used to contain Components, which are your basic UI controls.
• Layouts vs. fixed positioning of Components.
• Lowest common denominator approach to keyboard, mouse and event handling.
• High level of abstraction from the underlying GUIs. i.e no Non-clients areas, X calls, hWnds, etc.
• The look-and-feel of the application is dependant on the underlying GUIs rather than "one-size-its all".
• Not very device-independant(i.e can not assume a dialog will be the 'same size' on every computer) and the lack of ability to 'draw to the printer' rather than the screen.
• Lacks a resource format. Thus the ability to separate code from the interface, via designing the interface with a GUI builder and 'adding' event handling code. Albeit I've heard a Windows RC to AWT in development
• Class hierarchy is fairly shallow, but the AWT is not an application framework either. So it's missing a doc/view architecture.

Since the JDK 1.0 has been released. Applets and Application tend to have similar functionality. Yet there are times when an applet can not be a stand-alone app, but that case will soon disappear as shown between Beta 1 to the official "One-point Oh" release. Applets and Applications may one day have the same functionality.

Bugs in the AWT(JDK 1.0)

• Dialogs cannot be Modal
• clipRect is bugged
• Mouse events are quirky(especially mouseDown)

Steps for stand-alone applications using the AWT:

• Interface:
  1. Create your Frame
  2. Do initialization of fonts, colors, layouts and other resources
  3. Create your menus and menubars
  4. Create your controls, dialogs, windows, etc.
• Implementation
  1. Add event handlers
  2. Add functionality(i.e threading, networking, etc)
  3. Add error-handling(i.e exceptions)