CSI 3125, Preliminaries, page 1 AWT. CSI 3125, Preliminaries, page 2 AWT Java AWT (Abstract Windowing Toolkit) is an API to develop GUI or window-based

CSI 3125, Preliminaries, page 1

AWT


AWT• Java AWT (Abstract Windowing Toolkit) is an

API to develop GUI or window-based application in java.

• Java AWT components are platform-dependent i.e. components are displayed according to the view of operating system.

• The java.awt package provides classes for AWT API such as TextField, Label, TextArea, RadioButton, CheckBox, Choice, List etc.


Java AWT Hierarchy


AWT• Window Class• The two most common windows are • Panel, which is used by applets, • And Frame, which creates a standard window. • Much of the functionality of these windows is

derived from their parent classes.


AWT• Component class• At the top of the AWT hierarchy is the Component class.• Component is an abstract class that encapsulates all of the

attributes of a visual component that are displayed on the screen

• It defines over a hundred public methods that are responsible for managing events, such as mouse and keyboard input, positioning and sizing the window, and repainting.

• A Component object is responsible for remembering the current foreground and background colors and the currently selected text font.


AWT• Container class• The Container class is a subclass of

Component. • A container is responsible for laying out (that• is, positioning) any components that it

contains.• It does this through the use of various layout

managers


AWT• Panel class• The Panel class is a subclass of Container. • It doesn’t add any new methods; it simply implements

Container. • Panel is a window that does not contain a title bar, menu

bar, or border. • Other components can be added to a Panel object by its

add( ) method (inherited from Container). • Once these components have been added, you can position

and resize them manually using the setLocation( ), setSize( ), or setBounds( ) methods defined by Component.


AWT• Frame class• Frame encapsulates what is commonly

thought of as a “window.” • It is a subclass of Window and has a title bar,

menu bar, borders, and resizing corners. • When a Frame window is created by a

program rather than an applet, a normal window is created.


Frame Window• Frame’s constructors:• Frame( )• Frame(String title)• The first form creates a standard window that

does not contain a title. • The second form creates a window with the

title specified by title.


Frame Window• setSize( ) method is used to set the dimensions

of the window. • void setSize(int newWidth, int newHeight)• After a frame window has been created, it will

not be visible until you call setVisible( ). • void setVisible(boolean visibleFlag)• setTitle( ) used to set title• void setTitle(String newTitle)


Frame Window prog• import java.awt.*; • class frame1 extends Frame• { • frame1()• { • setSize(500,500); • setVisible(true);• }• public static void main(String args[]){ • frame1 f=new frame1(); • }• }


Frame Window• Closing a Frame Window• By calling setVisible(false). • Implement the windowClosing( ) method of

the WindowListener interface. • Inside windowClosing( ), call setVisible(false)


Frame Closing Prog• import java.awt.*; • import java.awt.event.*;• class frame1 extends Frame• { frame1()• { • addWindowListener(new My());• setSize(500,500); • setVisible(true);• }• class My extends WindowAdapter • {• public void windowClosing(WindowEvent me) • {• System.out.println("Closed");• setVisible(false);• }• }• public static void main(String args[]){ • frame1 f=new frame1(); }• }


Working with Graphics• Drawing Lines• Lines are drawn by means of the drawLine( ) method, • void drawLine(int startX, int startY, int endX, int endY)• Drawing Rectangles• The drawRect( ) and fillRect( ) methods display an

outlined and filled rectangle• void drawRect(int top, int left, int width, int height)• void fillRect(int top, int left, int width, int height)


Working with Graphics• To draw a rounded rectangle, use

drawRoundRect( ) or fillRoundRect( ), both• void drawRoundRect(int top, int left, int width, int

height, int xDiam, int yDiam)• void fillRoundRect(int top, int left, int width, int

height, int xDiam, int yDiam)• Drawing Ellipses• void drawOval(int top, int left, int width, int height)• void fillOval(int top, int left, int width, int height)


Working with Graphics• Drawing Arcs• Arcs can be drawn with drawArc( ) and fillArc( )• void drawArc(int top, int left, int width, int height, int

startAngle, int sweepAngle)• void fillArc(int top, int left, int width, int height, int

startAngle, int sweepAngle)


Working with Graphics• Drawing Polygons• It is possible to draw arbitrarily shaped figures

using drawPolygon( ) and fillPolygon( ),• void drawPolygon(int x[ ], int y[ ], int

numPoints)• void fillPolygon(int x[ ], int y[ ], int numPoints)


Working with Graphics Prog• import java.applet.*;• import java.awt.*;• public class awt2 extends Applet• {• public void paint(Graphics g)• {• g.setColor(Color.red);• g.fillRoundRect(100,100,200,200,30,40);• int x[]={10,20,30,100,40,300,550};• int y[]={2,44,55,66,77,345,123};• g.drawPolygon(x,y,7);• }• }• /*<applet code=awt2 width=500 height=500></applet>*/


Working with Colors• Color class have 3 constructors• Using this we can define our own colors• Color(int red, int green, int blue)• Color(int rgbValue)• Color(float red, float green, float blue)• The first constructor takes three integers that specify the color as a mix of red, green,and

blue. These values must be between 0 and 255, as in this example:• new Color(255, 100, 100); // light red.• The second color constructor takes a single integer that contains the mix of red, green, and

blue packed into an integer. • The integer is organized with red in bits 16 to 23, green in bits 8 to 15, and blue in bits 0 to

7. • Here is an example of this constructor:• int newRed = (0xff000000 | (0xc0 << 16) | (0x00 << 8) | 0x00);• Color darkRed = new Color(newRed);• The third constructor, Color(float, float, float), takes three float values (between 0.0• and 1.0) that specify


Working with Colors• Once you have created a color, you can use it

to set the foreground and/or background color by using the setForeground( ) and setBackground( ) methods

• eg• setBackground(new Color(200,100,230) );

• setForeground(new Color(200,100,230) )


Working with Fonts• Font f1 = new Font(String fontName, int fontStyle, int fontSize);• To give the font style as an integer value, the Font class comes with 3 symbolic

constants.• public final static int PLAIN = 0;

public final static int BOLD = 1;public final static int ITALIC = 2;

• Font font = new Font("Arial", Font.BOLD,20);

• OR• Font font = new Font("Arial", Font.BOLD+ Font.ITALIC,20);• OR

• g.setFont(font);


Working with Fonts• import java.applet.*;• import java.awt.*;• /*<applet code="M53" width=200 height=100> </applet>*/• public class M53 extends Applet • { • public void paint(Graphics g)• {• Font font = new Font("Arial", Font.BOLD,20);• g.setFont(font);• g.drawString("popo",50,50);• }•• }


Working with Fonts• import java.applet.*;• import java.awt.*;• /*<applet code="M53" width=200 height=100> </applet>*/• public class M53 extends Applet • { • public void paint(Graphics g)• {• Font f1 = new Font("Arial", 2,20);• g.setFont(f1);• g.drawString("Font Name: " + f1.getFontName(), 15, 80);• g.drawString("Font Style: " + f1.getStyle(), 15, 100); • g.drawString("Font Size: " + f1.getSize(), 15, 120); • g.drawString("isBold(): " + f1.isBold(), 15, 140);• g.drawString("isItalic(): " + f1.isItalic(), 15, 160); • g.drawString("popo",50,50);• }•• }


AWT


AWT

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CSI 3125, Preliminaries, page 1 AWT. CSI 3125, Preliminaries, page 2 AWT Java AWT (Abstract Windowing Toolkit) is an API to develop GUI or window-based