Java chapter 7

Java chapter 7

• 1.
  Java Applet Chapter 7
• 2.
  Java Applets • Overviewof Java Applets • Java Applets Vs Java Application
• 3.
  Java Applet • Appletis a special type of program that is embedded in the webpage to generate the dynamic content. It runs inside the browser and works at client side.
• 4.
  Advantage of Applet •There are many advantages of applet. They are as follows: – It works at client side so less response time. – Secured – It can be executed by browsers running under many platforms, including Linux, Windows, Mac OS etc. Drawback of Applet – Plug-in is required at client browser to execute applet.
• 5.
  Hierarchy of Applet Asdisplayed in this diagram, Applet class extends Panel. Panel class extends Container which is the subclass of Component.
• 6.
  Lifecycle of JavaApplet 1. Applet is initialized. 2. Applet is started. 3. Applet is painted. 4. Applet is stopped. 5. Applet is destroyed.
• 7.
  Lifecycle methods forApplet • The java.applet.Applet class 4 life cycle methods and java.awt.Component class provides 1 life cycle methods for an applet. java.applet.Applet class • For creating any applet java.applet.Applet class must be inherited. It provides 4 life cycle methods of applet. 1. public void init(): is used to initialized the Applet. It is invoked only once. 2. public void start(): is invoked after the init() method or browser is maximized. It is used to start the Applet. 3. public void stop(): is used to stop the Applet. It is invoked when Applet is stop or browser is minimized. 4. public void destroy(): is used to destroy the Applet. It is invoked only once.
• 8.
  Cont… java.awt.Component class • TheComponent class provides 1 life cycle method of applet. 1. public void paint(Graphics g): is used to paint the Applet. It provides Graphics class object that can be used for drawing oval, rectangle, arc etc. • Who is responsible to manage the life cycle of an applet? Ans. Java Plug-in software
• 9.
  How to runan Applet? • There are two ways to run an applet 1. By html file. 2. By appletViewer tool (for testing purpose).
• 10.
  Example import java.applet.Applet; import java.awt.Graphics; publicclass First extends Applet{ public void paint(Graphics g){ g.drawString("welcome",150,150); } }
• 11.
  Displaying Graphics inApplet Commonly used methods of Graphics class: 1. public abstract void drawString(String str, int x, int y): is used to draw the specified string. 2. public void drawRect(int x, int y, int width, int height): draws a rectangle with the specified width and height. 3. public abstract void fillRect(int x, int y, int width, int height): is used to fill rectangle with the default color and specified width and height. 4. public abstract void drawOval(int x, int y, int width, int height): is used to draw oval with the specified width and height. 5. public abstract void fillOval(int x, int y, int width, int height): is used to fill oval with the default color and specified width and height.
• 12.
  Cont… 6. public abstractvoid drawLine(int x1, int y1, int x2, int y2): is used to draw line between the points(x1, y1) and (x2, y2). 7. public abstract boolean drawImage(Image img, int x, int y, ImageObserver observer): is used draw the specified image. 8. public abstract void drawArc(int x, int y, int width, int height, int startAngle, int arcAngle): is used draw a circular or elliptical arc. 9. public abstract void fillArc(int x, int y, int width, int height, int startAngle, int arcAngle): is used to fill a circular or elliptical arc. 10. public abstract void setColor(Color c): is used to set the graphics current color to the specified color. 11. public abstract void setFont(Font font): is used to set the graphics current font to the specified font.
• 13.
  Example of Graphicsin applet import java.applet.Applet; import java.awt.*; public class GraphicsDemo extends Applet{ public void paint(Graphics g){ g.setColor(Color.red); g.drawString("Welcome",50, 50); g.drawLine(20,30,20,300); g.drawRect(70,100,30,30); g.fillRect(170,100,30,30); g.drawOval(70,200,30,30); g.setColor(Color.pink); g.fillOval(170,200,30,30); g.drawArc(90,150,30,30,30,270); g.fillArc(270,150,30,30,0,180); } }
• 14.
  Coding assignment • Animationin Applet • Painting in Applet • Digital Clock in Applet • Analog Clock in Applet