1. AWT

2. Objectives Abstract Window Toolkit (AWT)
Containers, Components and Layout Managers
Events and Event Handling

3. Building Java GUI

4. Abstract Window Toolkit
Provides graphical user interface (GUI) components.
Contains classes that can be extended and inherited.
Every GUI component displayed on screen is subclass of
Component or MenuComponent.
Has Container class which is subclass of Component and includes two subclasses.
Panel
Window

5. java.awt Package Object PopupMenu MenuBar MenuItem Menu
MenuComponent
CheckboxMenuItem
Object
Button Canvas
Applet
Checkbox Choice
Component
Panel
Container Label
Frame
Window Dialog
ScrollBar TextComponent
ScrollPane
FileDialog
TextArea TextField

6. Containers Add components with the add() method.
Two main types of containers are Window and Panel.
A Window is a free floating window on the display. Two important types of Window:
Frame
Dialog
A Panel is a container of GUI components that must exist in the context of some other container such as Window or Applet.

7. Building Graphical User Interfaces
The position and size of a component in a
container is determined by a layout manager.
Size or position of a component can be
controlled by disabling the layout manager.
Use setLocation, setSize() or setBounds() on components to locate components in the container.

8. Frame Subclass of Window. Have Title and resizing corners.
Are initially invisible, use setVisible(true) to show them.
Have BorderLayout as the default layout manager.
Use setLayout() method to change the default layout manager.

9. Frame Example Import java.awt.*;
public class FrameExample { private Frame f;
public FrameExample() {
f = new Frame("Hello Out There!"); }
public void launchFrame() { f.setSize(170, 170);
f.setBackground(Color.blue); f.setVisible(true); }
public static void main(String args[]) {
FrameExample guiWindow = new FrameExample(); guiWindow.launchFrame(); } }

10. Panel Panel is contained within another Container.
Provide space for Components.
FlowLayout is the default layout manager.
Allow subpanels to have their own layout manager.

11. Dialog It is a free standing window without the resizing corners.
Two types of Dialog:
Modeless: Allows the user to interact with other windows also.
Model: Doesn't allow to interact with other windows until it is closed
Dialog d = new Dialog(f, "Dialog", true); Button bt = new Button("OK"); d.add(bt);
d.pack();
d.setVisible(true);

12. AWT Components

13. Button
frame = new Frame("Button Sample"); button = new Button("Button");
button.addActionListener(this); frame.add(button);
frame.setSize(200, 200); frame.setVisible(true);

14. Checkbox
Frame = new Frame("Checkbox Sample"); checkbox1 = new Checkbox("One", true); checkbox2 = new Checkbox("Two", false); checkbox3 = new Checkbox("Three", false); checkbox1.addItemListener(this); checkbox2.addItemListener(this); checkbox3.addItemListener(this); frame.setLayout(new FlowLayout()); frame.add(checkbox1);
frame.add(checkbox2); frame.add(checkbox3);

15. CheckboxGroup
frame = new Frame("CheckBoxGroup Sample"); group = new CheckboxGroup ();
checkbox1 = new Checkbox("One", group, true); checkbox2 = new Checkbox("Two", group, false); checkbox3 = new Checkbox("Three", group, false);
checkbox1.addItemListener(this);
checkbox2.addItemListener(this); checkbox3.addItemListener(this);
frame.setLayout(new FlowLayout()); frame.add(checkbox1);
frame.add(checkbox2); frame.add(checkbox3);

16. Choice frame = new Frame("Choice Sample"); choice = new Choice();
choice.addItemListener(this);
choice.add("First");
choice.add("Second"); choice.add("Third");
frame.add(choice);

17. TextField
Frame = new Frame("TextField Sample"); tf = new TextField ("Enter Text", 30);
tf.addActionListener(this);
frame.add(tf);
frame.setSize(200, 70); frame.setVisible(true);

18. List frame = new Frame("List Sample"); list = new List(4, true);
list.addItemListener(this);
list.add("First");
list.add("Second"); list.add("Third");
frame.add(list);

19. How to create a Menu
Create a MenuBar Object and set it into menu container such as a Frame
Create one or more Menu objects and add them to menu bar object
Create one or more MenuItem objects and add them to menu object
Frame f = new Frame("MenuBar"); MenuBar mb = new MenuBar(); Menu m1= new Menu("File"); mb.add(m1);
f.setMenuBar(mb);

20. Controlling Visual Aspects
Colors:
setForeground();
setBackground();
Fonts:
setFont();
Font ft = new Font("TimesRoman", Font.PLAIN, 14); comp.setFont(ft);

21. Toolkit class
Toolkit class is an abstract superclass of all platform- specific implementations of the Abstract Window Toolkit
getDefaultToolkit - Returns current toolkit object
getImage(String fileName) - Loads an image from file
getScreenResolution - Returns number of "pixels per inch"
getScreenSize - Returns Dimension object having width and height of screen in pixels
getPrintJob - Returns PrintJob object

22. Printing Following code fragment prints a Frame
Frame frame = new Frame("Print Test"); Toolkit toolkit = frame.getToolkit();
PrintJob job = toolkit.getPrintJob(frame, "Test Printing", null); Graphics g = job.getGraphics();
frame.printComponents(g); g.dispose();
job.end();

23. Layouts
FlowLayout
BorderLayout
GridLayout
CardLayout
GridBagLayout

24. Default Layout Managers
Component
Container
Panel
Window
Applet
Frame
Dialog FlowLayout
BorderLayout

25. FlowLayout Manager Positions components on a line by line basis
Default Layout Manager for Panel Class
Components added from left to right
Default alignment is centered
Uses components preferred sizes
setLayout(new FlowLayout(int align, int hgap, int vgap));

26. BorderLayout Manager
It has five distinct areas: NORTH, SOUTH, EAST, WEST and CENTER
Default Layout Manager for Frame and Dialog Classes
Components are added to specific regions
The Resizing behaviour:
North, South and Center regions adjust horizontally.
East, West and Center regions adjust vertically.
setLayout( new BorderLayout(int hgap, int vgap) );

27. GridLayout Manager It divides whole area into cells
Components are added left to right, top to bottom.
All regions are equally sized.
The constructor specifies the rows and columns.
setLayout( new GridLayout(int rows, int cols) );

28. CardLayout Manager It treats the interface as a series of cards
Only one card can be viewed at any time
add() method is used to add cards to CardLayout
setLayout( new CardLayout() );

29. Drawing in AWT We can draw in any Component
although AWT provides Canvas class for drawing
paint() method for drawing
paint method is called everytime the component is shown
Every Component has a Graphics object
Graphics class implements many drawing methods

30. GUI Event Handling

31. What is an Event? Events:
Objects that describe what happened Event sources:
The generator of an event Event Handlers:
Method that receives an event object and processes the user interaction
Frame
User clicks button
Button
ActionEvent
Event Handler

32. Delegation Model
Client objects register with a GUI component they want to register
GUI components only trigger the handlers for the type of event that has occurred
Delegation model distributes the work among multiple classes

33. Event Categories java.awt.event ActionEvent FocusEvent
AdjustmentEvent InputEvent
KeyEvent MouseEvent
ContainerEvent ComponentEvent
WindowEvent ItemEvent
TextEvent

34. Event Categories Category Interface Name Action ActionListener Item
ItemListener
Mouse
MouseListener
Mouse Motion
MouseMotionListener
Key
KeyListener
Focus
FocusListener
Adjustment
AdjustmentListener
Component
ComponentListener
Window
WindowListener
Container
ContainerListener
Text
TextListener

35. Multiple Listeners
Multiple listeners cause unrelated parts of a program to react to the same event
The handlers of all registered listeners are called when the event occurs

36. Event Adapters The user defined listener classes can
extend adapter classes and override the methods that are needed
Adapter classes implement each interface containing more than one method and provide empty implementation of methods