Java GUI Components and Event Handling: Swing vs AWT, Slides of Network security

Download Java GUI Components and Event Handling: Swing vs AWT and more Slides Network security in PDF only on Docsity!

Objectives

• use an image viewer application to introduce Java's GUI features

11. Introducing

Java's GUI Features

Topics

• 1. GUI Principles
• 2. Background
• 3. Three Steps to GUIs
• 4. An Applicaton Window
• 5. Adding Menus
• 6. Event Handling
• 7. ImageViewer as a Listener

continued Docsity.com

1. GUI Principles

listeners (waiting code)

events (info. objects) components

layout manager

1. GUI Principles

• GUIs are built from components
  • buttons, menus, sliders, etc.
• The positioning of GUI components in a

window is done with layout managers

• User actions are converted into events
  • button presses, menu selections, etc.
• Events are processed by listeners.

2.1. Swing and AWT

• In older Java programs, the AWT (Abstract Window Toolkit) GUI components are used - Swing has replaced AWT GUIs - never mix Swing and AWT components in a single program
• Some parts of AWT are still used
  • e.g. its layout managers (see later)

continued Docsity.com

use Swing

• AWT supports heavyweight GUI components
  • each Java GUI component is actually a simple layer hiding the OSes GUI component - the OS component is called a peer component
  • e.g. on Windows, a Java button in AWT is implemented using a Windows' button

continued Docsity.com

2.2. Disadvantages of AWT

• Java does not have complete control over the AWT GUI components - some AWT GUIs do not work well because of problems with the underlying OS (e.g. file choosing in Windows)
• The "look and feel" of Java GUIs in AWT vary between OSes.

Some Java"Look and Feel"s

Using the Substance L&F add-on library (https://substance.dev.java.net/)

4. An Application Window

title

content pane

window controls

Implemented by subclassing JFrame

Coding an Application

public class ImageViewer extends JFrame { public ImageViewer() { super("ImageViewer 0.1");

// create the GUI Container c = getContentPane(); JLabel label = new JLabel ("I am a label. I can display some text."); c.add(label); :

JLabel is a GUI component

Version 0.

Sizing the Application

• Replace setSize() by pack():

5. Adding Menus

• JMenuBar
  • contains the menus
• JMenu
  • contains the menu items
• JMenuItem
  • individual items in a menu