interactive java note - java applets

8/3/2019 Interactive Java Note - Java Applets

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Programming Language (JAVA)

Unit 6.11 Applets

Presentation 1


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Pengaturcaraan Applet

Applets adalah program Java yang dilaksanakandengan Web browser .

Appletviewer adalah utiliti Java yangmelaksanakan applet.

Applet adalah fail kelas yang khas ditulis untukmemaparkan grafik dalam Web browser .


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Applets

Applets dimuatkan dalam laman Webmenggunakan tag HTML . Apabila laman Web yang mengandungidilarikan, ianya dimuat turunkan ke memorisecara automatik dan dilaksanakan oleh Web browser .

Applet dipaparkan dalam ruang yang tertentudalam laman Web page dipanggil AppletWindow.


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Applets

Applet boleh mengandungi objek-objek yangdimuatkan seperti :

Animated graphics

Video games

Advanced text displays and images

Audio


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Jenis Applet

Local Applets

Applets yang disimpan di dalam local machine

Remote AppletsApplets yang disimpan dalam remote computer .

Ini boleh dimuat turunkan dan diletakkan dalam lamanWeb dari Internet.


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Local Applets


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Remote Applets


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Metod asas Applet

Ada 5 metod asas :

1. init()

2. start()

3. stop()

4. destroy() 5. paint(Graphics g)


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Life Cycle of Applets


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init()

Syntax

public void init( )

{

;

}


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paint()

Syntax

public void paint(Graphics g)

{ ;

}


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Kelas Applet

Semua applet yang dicipta perlu menjadi subkelas kepada kelas Applet .

Program Applet perlu import 2 pakej iaitu, awtdan applet atau swing.


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Class Inheritance of Applet Class


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Execution of Applet


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tag

Syntax

/*


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Sections of Web page

Comment Section Mengandungi komenmengenai laman web.

Head Section mengandungi tajuk laman Web.

Body Section mengandungi teks dan arahanyang menentukan bagaimana teks, imej,animasi dan sebagainya patut wujud dalamlaman Web.

Tag Applet dimasukkan dalam body section .


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Sample Applet


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Kelas Grafik

Ciri yang paling penting bagi Java adalahmenyokong grafik.

Anda boleh menulis applet untuk melukisgarisan, pelbagai bentuk , imej dan teksdalam pelbagai jenis font dan gaya.

Saiz tetingkap applet didefinisikan olehattribut tag .


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Metod Kelas Grafik

Method Description

clearRect( ) Erases a rectangular area of thecanvas.

copyArea( ) Copies a rectangular area of the canvasto another area.

drawArc( ) Draws a hollow arc.

drawLine( ) Draws a straight line.

drawOval() Draws a hollow oval.


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Metod Kelas Grafik

Method Description

drawPolygon( ) Draws a hollow polygon.

drawRect( ) Draws a hollow rectangle.

drawroundRect( ) Draws a hollow rectangle withrounded corners.

drawstring( ) Displays a text string.

fillArc( ) Draws a filled arc.


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Metod Kelas Grafik

Method Description

fillOval( ) Draws a filled oval.

fillPolygon( ) Draws a filled polygon.

fillRect( ) Draws a filled rectangle.

fillRoundedRect( ) Draws a filled rectangle withrounded corners.


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Metod Kelas Grafik

Method Description

getColor( ) Retrieves the current drawingcolour.

getFont( ) Retrieves the currently usedfont.

setColor( ) Sets the drawing colour.

setFont( ) Sets the font.


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Melukis garisan

Semasa melukis garisan dalam tetingkap appletwindow menggunakan metod drawLine( ) , andaperlu sepasang koordinat.

Contoh:

g.drawLine(20,20, 60,60);


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Drawing a Circle and an Ellipse The drawOval() method is used to draw acircle or an ellipse.

Example:

g.drawOval(10,20,50,30);

fillOval() is similar to drawOval() but fills theoval with a colour.


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Drawing a Rectangle

drawRect( ) method is used to draw arectangle. This method takes four arguments.

Example:

g.drawRect(20,70, 30,40);


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Draw Rectangle

The fillRect() method is similar to drawRect() method but the fillRect() method fills the

rectangle with a colour.The drawRoundRect() method is similar todrawRect() method but drawRoundRect() method draws a rectangle with rounded corners.

The fillRoundRect() method is similar todrawRoundRect() method butfillRoundRect() method fills the rectangle witha colour.


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setColor()

The setColor() method is used to set thecurrent foreground colour.

The following code creates an object of Colorclass and sets the foreground colour to red.

Color col=new Color(255,0,0);

g.setColor(col);

The foreground colour can also be set using g.setColor(Color.Red);


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getColor()

The getColor() method is used to get thecurrent foreground colour of the applet.

The following is the code to get the currentforeground colour.

g.getColor();

interactive java note - java applets

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