This document discusses interfaces and packages in Java. It defines an interface as a special Java class that is fully abstract and contains only static final variables and abstract methods. Interfaces can extend other interfaces but not classes. Classes can implement multiple interfaces but extend only one class. Packages in Java organize related classes and interfaces. The Java API contains predefined packages like java.lang and java.util while user-defined packages can be created using the package keyword.

1. SOFT SKILLS AND
PERSONALITY DEVELOPMENT
TOPIC:INTERFACE AND PACKAGES
SUBMITTED BY
MOHAMMAD AZHAR UD DIN
ROLLNO:13YYSB6009

2. *
An interface is a keyword , it is a special java class
which is fully abstracted.
•There are two types of interface:-
-Public final static variables.
-Public abstract methods .
•To inherit interface by a class then use the keyword
‘Implements’
• To inherit interface by an interface then use the
keyword ‘Extends’
Syntax :
Interface interfacename
{
Variable declaration
Method declaration
}

3. - An interface can extends one or more interfaces
- Interface cannot extends class
- Interface cannot implements interfaces
- Class can extends at most only one class
- Class can implements one or more interfaces
- A class can extends one class and implements multiple
interface at the time.
Syntax: Class sub-class extends super class implements
interface 1,… n;
Interface

4. Example : for implementing interface
Interface one
{
Int i = 10;
Void show();
}
Class two implement one
{
Void show()
{
System.out.print(i);
}
}
Class Sample
{
Public static void main(String
a[])
{
Two t = new two();
t.show()
}
}

5. Example for extending Interface:
Interface one
{
Abstract void show();
}
Class sam1 implements one
{
Int a, b;
Sam1(int i, int j)
{
a = i ;
b = j;
}
Void show()
{
System.out.print(a);
System.out.print(b);
}
{
Abstract class sam2 implements
one
{
Void print()
System.out.print(“sam2 class”)
}
}
Class sam3 extends sam2
{
Void show()
{
System.out.print(sam3 class”);
}
}
Class sample
{
Public static void main(String a[])
{
Sam1 s1 = new sam1(10 , 20);
s1.show();
Sam2 s3 = new sam3 ();
s3.print();
s3.show();
}
}

6. THE DIFFERENCES BETWEEN CLASS AND
INTERFACES
Class
• Class can implement more
Than one interface.
•Class contain design and
implementation of code.
* contains constants, variables and
Methods.
•Class can be instantiated.
Interface
*Interface can extend more than
one interface
•Pure design.
•Contains constants and abstract
methods.
*Interfaces can’t be instantiated.

7. DEFINING INTERFACES
The general form of a definition is
Interfaces <INTERFACE NAME>
{
<Final Fields>
<abstract methods>
}

8. Extending interfaces
The Interfaces can be extended .
That is an inheritance
Can extended from another
interface.
•Sub Interface
•Super Interface
Super interface
Interface

9. TYPES OF PACKAGES
Packages is collection of a class or interfaces.
Two types of packages are there:
Java API Packages
User defined Packages
i. Java API packages provides larges no. of classes grouped into
different package to functionality.
java
Lang utile io awt net applet

10. I. Java . lang.*: This package includes in classes for primitive type
, math functions threads , string and exceptions
II. Java . util.*: This package contains classes such as data , vector,
hash table
III. Java.io.*: This package contains classes that support input and
output operation.
IV. Java.awt.*: This package contains set of classes for
implementing graphical user interface. It include buttons menu
, window etc.
V. Java.net.*: This packages contains classes for networking , it
includes classes for communicating with local & internet server.
VI. Java . applet.*: This package includes for creating and
implementing applets
APPLICATION PROGRAMMING INTERFACE
PACKAGES DEFINITION

11. User defined packages:
This are the packages that are defined by user
or programmer.
o Creating packages:
Syntax: package packagesname;
‘package’ is a keyword and packagename is
identifier.
E.g : package p1;
o Accessing packages.
Packages can be access using ‘import’ statement
Import package1 [.package 2][.package
3].classname;