8 - Graphical User Interface (GUI) Applications

AWT

• Single Windowing Interface on Multiple Platforms

• Supports functions common to all window systems

• Uses Underlying Native Window system

Abstract Windowing Toolkit

What does AWT stand for?

• GUI widgets

• Event Handling

• Containers for widgets

• Layout managers

• Graphic operations

AWT provides…

Portable GUI

preserves native look and feel

Standard GUI Components

Buttons, menus, checkboxes, etc.

Containers

Panels, Frames, Designs

BorderLayout, GridLayout, FlowLayout, Null layout

Layouts responsible for actual positioning of components:

What do adding components via the BoarderLayout look like?

What do adding components via the GridLayout look like?

What do adding components via the FlowLayout look like?

What do adding components via the Null Layout look like?

1. import java.awt.*;

   • Assemble the GUI

   • use GUI components, 

2. basic components (e.g., Button, TextField)

3. containers (Frame, Panel)

   • set the positioning of the components

4. use Layout Managers

5. Attach events

Steps to building Graphical User Interfaces

What is the output of the following?

import java.awt.*;
public class MyGui 
{
	public static void main(String args[] ) 
	{ 
		Frame f = new  Frame ("My Frame");
		Button b = new Button("OK");
		TextField tf = new TextField("Programming in Java", 20);
		f.setLayout(new FlowLayout());
		f.add(b);
		f.add(tf);
		f.setSize(300, 300);
		f.setVisible(true);
	}
}

Listener

Each GUI component (e.g., a Button) that wishes to respond to an event type (e.g., click), must register an event handler, called a?

an object of a "Listener" interface.

The listener is an object of?

A Listener class can be created by subclassing (through "implements") one of Listener interfaces (all listener inrefaces are in the java.awt.event package = > must import java.awt.event.*; )

A Listener class can be created by?

The registration of the listener is done by a call to a method such as:

addActionListener(<Listener Object>).

How to register the listener?

[1] ActionListener

[2] ItemListener

[3] MouseMotionListener

[4] MouseListener

[5] KeyListener

[6] FocusListener

[7] AdjustmentListener

[8] ComponentListener

[9] WindowListener

[10] ContainerListener

[11] TextListener

Listener Interfaces in java.awt.event.*

Each listener interface has methods that need to be implemented for handling different kinds of events.

How do you handle different kinds of events and listeners?