1

Basics and Features of Java

2

Objectives

On completion of this period, you would be able to know

• The features of Java Applets and Applications

3

Recap

• What is an applet?

• Differentiate Java with C++

• Why Java is important to internet?

4

Features of Java applications

Sun Micro Systems officially describes Java with the following features

• Compiled and Interpreted • Platform Independent and Portable• Object Oriented• Robust and Secure• Distributed

5

• Simple, Small and Familiar

• Multithreaded and Interactive

• High Performance

• Dynamic and Extensible

Features of Java applications Contd..

6

Compiled and Interpreted

• Usually a computer language is either compiled or

interpreted

• Java combines both these approaches, thus making

Java a two stage system

• First Java compiler translates source code into

byte code instructions

• Byte codes are not machine instructions

7

Compiled and Interpreted • In the second stage Java interpreter generates

machine code

• That can be directly executed by the machine

Contd..

Fig. 2.1 Compiled and Interpreted

8

Platform Independent and Portable

• The most significant feature of Java is its

portability

• Java programs can be easily moved from one

computer system to another ,anywhere and at

anytime

9

• Changes and upgrades in

• Operating systems

• Processors

• System resources

will not force any changes in Java programs

Platform Independent and Portable Contd..

10

Platform Independent and Portable Contd..

Fig. 2.2 Once compiled, Java class file can be run on any platform

11

Object Oriented

• Java is a true object oriented language

• Almost everything in Java is an object

• All programs code and data reside within objects

and classes

• Java comes with an extensive set of classes

arranged in packages

12

Robust and Secure

• Java is a robust language

• It provides many safeguards to ensure reliable code

• It has strict compile time and runtime for data types

13

• It is designed as a garbage collected language

• Java also provides concept of exception handling which identifies errors and eliminates

Robust and Secure Contd..

14

• Security becomes an important issue for a

language that is used for programming on internet

• Threat of viruses and abuse of resources

• Java systems not only verify all memory access,

but also ensure that no viruses are communicated

with an applet

Robust and Secure Contd..

15

• The absence of pointers in Java ensures that

programs cannot gain access to memory location

without proper initialization

Robust and Secure Contd..

16

Distributed

• Java is designed as a distributed language for

creating applications on networks

• It has the ability to share both data and programs

17

• Java applications can open and access remote

object as easily as they can do in a local system

• Enables multiple programmers at multiple

locations work together on a single project

DistributedContd..

18

Simple, Small and Familiar • Java is small and simple language. Many features

of C and C++ are not part of Java

eg. : Java does not provide • Pointers• Preprocessors header file• goto statements• Operator overloading • Multiple inheritance

19

• Familiarity is another feature of Java

• It is modeled on C and C++ languages

• Java is a simplified version of C++

Simple, Small and Familiar Contd..

20

Multithreaded and Interactive

• Multithreaded means handling multiple

tasks simultaneously

• Java supports multithreaded programs

• Need not wait for the application to finish

one task before beginning another

• Greatly improves the interactive

performance of graphical applications

21

High Performance

• Java performance is impressive for an interpreted

language

• Due to the use of intermediate byte code

• Java architecture is also designed to reduce

overheads during runtime

• The incorporation of multithreading enhances the

overall execution speed of Java programs

22

Dynamic and Extensible

• Java is a dynamic language• Java is capable of dynamically linking new

• Class libraries• Methods • Objects

• Java programs supports functions written in other languages such as C and C++

• These functions are known as “native methods”

23

• This facility enables the programmers to use the

efficient available in these languages

• Native methods are dynamically linked at runtime

Dynamic and Extensible Contd..

24

Summary

• Features of Java Applications

• Features of Java Applets

25

Quiz

1.Usually a computer language is either ______

a) Compiled

b) Compiled and Interpreted

c) Compiled or Interpreted

d) Interpreted

26

Frequently Asked Questions

• Explain the features of Java Applications and Java

Applets

swingsStrutsjdbchibernatehomejava previous question papers OCT/NOV-2012 QUESTION PAPERApril / May 2012 c-09October/ November-2011 c-09April/ May 2011 c-09April/ May 2011 c-05

  

27