1. “Packages in Java”

2. Contents Introduction Classification Java API packages
Using system packages
Naming conventions
Creating package
Accessing package
Using a package
Conclusion
Bibliography

3. Introduction
Packages are Java’s way of grouping a variety of classes and/or interfaces together

4. Classification Java packages are classified into two types 1) Java API
2) User defined packages

5. Java API package
JAVA
lang
util io
awt
net
applet

6. Using system package Java awt Package containing awt package Color
Graphics
Package containing classes
Font
Classes containing methods
Image

7. Naming convention double y = java . lang . Math . sqrt (x);
Package name
Class name
Method name

8. Creating package package firstPackage; public class FirstClass {
……………………… }
(Body of class)

9. Continued….
Declare the package at the beginning of a file using the form
Define the class that is to be put it the package and declare it public
Create a sub directory under the directory where the main source files are stored
package packagename;

10. Continued……
Store the listing as the classname .java file in the sub directory created
Compile the file. This creates .class file in the sub directory

11. Accessing a Package import package1 [.package2]
[.package3] .classname;

12. Using a Package
package package1; public class ClassA { public void displayA() System.out.println(“welcome”); s } }

13. Cont..
import package1.classA; class Test { public static void main(String args[]) classA obj=new classA(); obj.displayA(); }

14. conclusion
Ability to reuse the code within the same programs is achieved in oops by means of extending and implementing. Including this property java also provides a mechanism,that is reuse of the code out side the program without physical copy, is achieved by using packages.