Structure of java program diff c- cpp and java

Topics for Today’s Session
Differences between C,
C++ & Java
Structure of a Java
Program

Differences between C, C++ and Java
Feature C C++ Java
Programming
Paradigm
Procedural
language
Object-Oriented
Programming (OOP)
Pure Object
Oriented Oriented
Origin
Based on assembly
language
Based on C language Based on C and C++
Developer
Dennis Ritchie in
1972
Bjarne Stroustrup in
1979
James Gosling in
1991
Translator Compiler only Compiler only
Interpreted language
(Compiler + interpreter)
Platform
Dependency
Platform Dependent Platform Dependent
Platform
Independent
Code execution Direct Direct Executed by JVM
Approach Top-down Bottom-up Bottom-up
File generation .exe files .exe files .class files
Pre-processor
directives
Support header files
(#include, #define)
Supported (#header,
#define)
Use Packages
(import)
keywords 32 keywords 63 keywords 50 keywords

Contd..
Feature C C++ Java
Datatypes (union,
structure)
Supported Supported Not supported
Inheritance No inheritance Supported
Supported except
Multiple inheritance
Overloading No overloading
Support Function overloading
(Polymorphism)
Operator overloading is
not supported
Pointers Supported Supported Not supported
Allocation Use malloc, calloc Use new, delete Garbage collector
Exception Handling Not supported Supported Supported
Templates Not supported Supported Not supported
Destructors
No constructor
neither destructor
Supported Not supported
Multithreading/
Interfaces
Not supported Not supported Supported
Database
connectivity
Not supported Not supported Supported
Storage Classes
Supported ( auto,
extern )
Supported ( auto, extern ) Not supported

Documentation Section:
 It includes the comments that improve the readability of the
program.
 It consists comments in Java that describe the purpose of the
program, author name, date and time of program creation.
 This section is optional and comments may appear anywhere
in the program.
Java programming language supports three types of
comments..
 Single line Comment (or end-of line comment)
 It starts with a double slash symbol (//) and terminates at the end
of the current line.
Ex: // sum of two numbers
 Multi-line Comment
/* a multi-line comment is declared like this
and can have multiple lines as a comment */
 Documentation Comment
 /** a documentation comment starts with a delimiter and ends
with */

Package Statement
 A package is a collection of classes, interfaces and sub-
packages.
 A sub package contains collection of classes, interfaces and
sub-sub packages etc.
 There is a provision in Java that allows you to declare your
classes in a collection called package.
 There can be only one package statement in a Java program.
 It must appear as the first statement in the source code file
before any class or interface declaration.
 This statement is optional,
Syntax: package package_name;
Example: package student;
 This statement declares that all the classes and interfaces
defined in this source file are a part of the student package.
java.lang.*;
package is imported by default and this package is
known as default package.

Import Statement
 Many predefined classes are stored in packages in Java, an
import statement is used to refer to the classes stored in other
packages.
 An import statement is always written after the package
statement but it has to be before any class declaration.
 You can import a specific class or all the classes of the
package.
 Many classes can be imported in a single program and hence
multiple import statements can be written.
import java.util.Date; //imports the date class
import java.applet.*; //imports all the classes from the java applet package

Interface Section
 This section is used to specify an interface in Java.
 It is an optional section which is mainly used to implement
multiple inheritance in Java
 An interface is similar to a class but contains only constants
and method declarations.
 An Interfaces cannot be instantiated.
 They can only be implemented by classes or extended by other
interfaces.
Interface shape{
void draw(int length, int bredth);
void show();
}

Class Definition
 Java program may contain multiple class definition.
 Classes are primary feature of Java program.
 The classes are used to map real world problems.
 classes defines the information about the user-defined classes
in a program.
 A class is a collection of variables and methods that operate on
the fields.
 Every program in Java will have at least one class with the main
method.
class Addition
{
void add(String args[])
{
int a=2, b=3, c;
c=a+b;
System.out.println(c);
}
}

Main Method Class
 Execution of a Java application starts from the main method.
 In other words, its an entry point for the class or program that
starts in Java Run-time.
 The main () method which is from where the execution of program
actually starts and follow the statements in the order specified.
 The main method can create objects, evaluate expressions, and invoke
other methods and much more.
 On reaching the end of main, the program terminates and control
passes back to the operating system.
 The class section is mandatory.
// Program to display message on the screen
class HelloJava {
public static void main(String args[])
{
System.out.println("Hello Harsha");
} }

Summary
 In this lesson you learnt about
 Java
 Differences between C , C++ and Java
 Structure of Java Program

Structure of java program diff c- cpp and java

Structure of java program diff c- cpp and java

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