Java Presentation

WELCOME JAVA PRESENTATION

TOPIC OF PRESENTATION
APPLET
Created By :
Prashant Marvania

Overview of APPLET
What is Applet?
Advantages of Applet
Disadvantages of Applet
The Life Cycle of an Applet
The format of <APPLET> tag
Attributes of the <APPLET> tag
Example of an Applet

What is Applet?
Applet is a JAVA programme that can be embedded into HTML page.
JAVA Applet runs on the java enables web browsers such as MOZILA and INTERNET EXPLORER.
Applets are used to make the web site more dynamic and entertaining.

Advantages of Applet
There are many advantages of Applet:
Cross platform and can run on Windows, MacOS and Linux platform.
Applet can work all the version of java plugin.
Applets run in a sandbox.
Applets are supported by most web browsers.
Applets are cached in most web browsers.

Disadvantages of Applet
There are many disadvantages of Applet:
Java plug-in is required to run Applet.
Java Applet requires JVM.
If Applet is not already cached in the machine, it will be downloaded from internet and will take time.
Its difficult to design and build good user interface in Applets compared to HTML technology.

The Life Cycle of an Applet
In Applet, there are 4 methods in Life Cycle:
1.init()
2.start()
3.stop()
4.destroy()

Init() and start() methods
Init():
This method is called to initialized an
Applet.
Start():
This method is called after the
initialization of the Applet.

Stop() and destroy() methods
Stop():
This method can be called multiple
times in the life cycle of an Applet.
Destroy():
This method is called only once in
the life cycle of an Applet when Applet
is destroyed

The format of <APPLET> tag
<APPLET attributes>
applet_parameters
alternate_content
</APPLET>

Attributes of the <APPLET> tag
There are many attributes of the <APPLET> tag.
1.CODE = appletFile
2.WIDTH = pixels
3.HEIGHT = pixels

Example of an Applet
import javax.swing.*;
import java.awt.*;
import java.applet.*;
/*
<applet code=“ImageEx” height=100 width=100>
</applet>
*/
public class ImageEx extends Applet
{
public void paint( Graphics g )
{
Image img = getImage( getCodeBase( ), “ Lion.jpg" );
g.drawImage( img, 0,0, this );
}
}
RUN THE APPLET:
javac ImageEx.java
appletviewer ImageEx.java

Output of a programme

TOPIC OF PRESENTATION
PACKAGE
Created By :
Prashant Marvania

Packages
A package is a grouping of related types providing access protection and name space management.
Types are special kinds of classes and interfaces.

You should bundle these classes and the interface in package for several reasons.
1.You and other programmers can easily determine that these types are related.
2.You and other programmers where to find types that can provide graphics-related functions.
3.The name of your won’t conflict with the type names in other packages.
4.You can allow types within the package to have unrestricted access to one another yet still restrict access for types outside the package.

Creating a Package
To create package, you choose a name for the package and put a package statement with that name the top of every source file that contains the types that you want to include in the package.

Naming a Package
With programmers worldwide writing classes and interfaces using the java programming language, it is likely that many programmers will use the same name for different types.

Naming Conventions
Package names are written in all lowercase to avoid conflict the names of classes or interfaces.
Companies use their reversed internet domain name to begin their package names.
Package in the java language itself begin with java or javax.

Using package members
To use a public package member from outside its package. you must do one :
1.Refer to the member by its fully qualified name.
2.Import the package member.
3.Import the member’s entire package.

Refer to package
Graphics. Rectangle
You could use this name to create an instance of graphics. Rectangle
Graphics. Rectangle myrect=new Graphics. Rectangle ();

Import a package member
To import a specific member into the current file, put an import statement at the beginning of the file before any type definitions but after the package statement, if there is one.
Import graphics. Rectangle;

Import entire package
To import all the types contained in a particular package, use the import statement with asterisk(*) wildcard character.
Import graphics.*;

Managing source and class files
Many implementations of the java platform rely on hierarchical file systems to manage source and class files, although the java language specification does not require this.

The qualified name of the package member and the path name to the file are parallel, assuming the Microsoft windows file name separator backslash.
Class name graphics. Rectangle
Pathname to file graphicsRectangle. java

Each component of the package name corresponds to a subdirectory.
It would be contained in a series of subdirectories like this:
… comexamplegraphicsReactangle.java

A class path may include several paths, separated by a semicolon (windows) or colon (UNIX).
By default the compiler and the jvm search the current directory and the jar file containing the java platform classes so that these directories are automatically in your class path.

THANK YOU

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