Simple :

• Java is Easy to write and more readable and eye catching.
• Java has a concise, cohesive set of features that makes it easy to learn and use.
• Most of the concepts are drew from C++ thus making Java learning simpler.

Secure :

• Java program cannot harm other system thus making it secure.
• Java provides a secure means of creating Internet applications.
• Java provides secure way to access web applications.

Portable :

• Java programs can execute in any environment for which there is a Java run-time system.(JVM)
• Java programs can be run on any platform (Linux,Window,Mac)
• Java programs can be transferred over world wide web (e.g applets)

Object-oriented :

• Java programming is object-oriented programming language.
• Like C++ java provides most of the object oriented features.
• Java is pure OOP. Language. (while C++ is semi object oriented)

Robust :

• Java encourages error-free programming by being strictly typed and performing run-time checks.

Multithreaded :

• Java provides integrated support for multithreaded programming.

Architecture-neutral :

• Java is not tied to a specific machine or operating system architecture.
• Machine Independent i.e Java is independent of hardware .

Interpreted :

• Java supports cross-platform code through the use of Java bytecode.
• Bytecode can be interpreted on any platform by JVM.

High performance :

• Bytecodes are highly optimized.
• JVM can executed them much faster .

Distributed :

• Java was designed with the distributed environment.
• Java can be transmit,run over internet.

Dynamic :

• Java programs carry with them substantial amounts of run-time type information that is used to verify and resolve accesses to objects at run time.

In this tutorial we have covered step by step discussion about –

1. Which features makes java Platform Independent ?
2. Why Java is Platform Independent ?
3. Why Java is considered as Secure and Portable Language ?

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A. Java is considered as Portable because –

Java is Considered as Platform independent because of many different reasons which are listed below –

1. Output of a Java compiler is Non Executable Code i.e Bytecode.
2. Bytecode is a highly optimized set of instructions
3. Bytecode is executed by Java run-time system, which is called the Java Virtual Machine (JVM).

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Important Note :

As the output of Java Compiler is Non Executable Code we can consider it as Secure (it cannot be used for automated execution of malicious programs).

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4. JVM is an interpreter.
5. JVM accepts Bytecode as input and execute it.
6. Translating a Java program into bytecode makes it much easier to run a program in a wide variety of environments because only the JVM needs to be implemented for each platform.
7. For a given System we have Run-time package , once JVM is installed for particular system then any java program can run on it.
8. However Internal details of  JVM will differ from platform to platformbut still all understand the Same Java Bytecode.

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How Java Program is Platform Independent ?

B. Why Java Code is Safe ?

1. Java program is executed by the JVM.
2. The JVM prevent java code from generating side effects outside of the system.
3. Safety is also enhanced by certain restrictions that exist in the Java language.

C. Interpreter are slower than Compiler

Java Code is Executed by JVM (interpreter).Other programming language uses compiler which can create executable code much faster then why we are using Interpreter.

1. When a program is interpreted, it generally runs slower than the same program would run if compiled to executable code.
2. In Java Compiler will generate ByteCode which is highly optimized.
3. Thus running highly optimized code using interpreter makes execution ofjava program faster.

1. Great feature of the java is that java is platform independent.
2. It can word on any network,any operating system thus making programs more flexible.
3. In addition to simplifying web programming in general, Java innovated a new type of networked program called the applet that changed the way the online world thought about content.
4. Portability and Security of java makes World wide web to spread across globe.

A. Java Applets :

1. An applet is a special kind of Java program that is designed to be transmitted over the Internet and automatically executed by a Java-compatible web browser.
2. Applet can be downloaded on demand.
3. Applet programs can be run on ant java compatible browser.
4. Applets are intended to be small programs.
5. They are typically used to display data provided by the server, handle user input, or provide simple functions, such as a loan calculator, that execute locally, rather than on the server.
6. In essence, the applet allows some functionality to be moved from the server to the client.

B. Security :

1. Applets can be downloaded to user PC .
2. They are executed independently without accessing other parts of user’s PC.
3. The ability of Java provides security and thus Java prove itself more secure.

C. Portability :

1. Java Programming is Portable.
2. Java Program is Operating System Independent.
3. Java Program is converted into byte code and byte code is executed by JVM. [ See how Java Code is Portable ? ]
4. Java Applets are thus portable and can be downloaded from any place in globe and can be executed on java compatible browser thus making java programs portable.

1. After the creation of Java, Microsoft developed the C# language and C# is closely related to Java.
2. Many of C#’s features directly parallel Java. Both Java and C# share the same general C++-style syntax, support distributed programming, and utilize the same object model.
3. Though there are some differences between Java and C#, but the overall feel of these languages is very similar.
4. If you already know C#, then learning Java will be easy and vice versa
5. Java and C# are optimized for two different types of computing environments.
6. C# and Java Both Languages are drew from C++.
7. Both Languages are capable of creating cross platform portable program code.

[box]Important : How do Java & C# create cross-platform portable Code ?[/box]

Consider Scenario of Java Programming Language

1. Java is created by Sun Micro System.
2. Java Compiler produces Intermediate code called Byte Code.
3. Byte Code i.e intermediate code is executed by the Run Time Environment.
4. In Java Run Time Environment is called as “JVM” [ Java Virtual Machine]
5. If we have JVM already installed on any platform then JVM can produce machine dependent Code based on the intermediate code.

Java Vs C Sharp

Here are some differences between Java and C Sharp.

Point	Java	C#
Development	Sun Microsystem	Microsoft
Development Year	1995	2000
Data Types	Less Primitive DT	More Primitive DT
Struct Concept	Not Supported	Supported
Switch Case	String in Switch Not Allowed	String in Switch Allowed
Delegates	Absent	Supported

What is Java ?

Java is widely used programming language which has wide verity of applications such as desktop applications, Mobile Applications, Enterprise applications etc.

Java is a –

1. Class Based and Object Oriended Programming Language
2. Computing platform
3. Fast, Secure, and Reliable.
4. Free
5. General Purpose
6. Concurrent

Five primary goals in the creation of the Java language :

1. It should be “simple, object-oriented and familiar”.
2. It should be “robust and secure”.
3. It should be “architecture-neutral and portable”.
4. It should execute with “high performance”.
5. It should be “interpreted, threaded, and dynamic”.

1. Java was designed by Sun Microsystems in the early 1990s.
2. Basic aim of java was to solve the problem of connecting many household machines together.
3. Project was unsuccessful because no one wanted to use it.
4. Earlier Name of Java : OAK
5. Creator of Java :  James Gosling  (the father of Java)
6. As there was another language called Oak , they decided to rename OAK. New name was given to OAK , OAK was renamed Java in 1994
7. Java was publicly released on : May 27, 1995
8. Java was targeted at :  Internet development
9. Applets Had early support from companies : Netscape Communications

Language was created with 5 main goals:

1. It should be object oriented
2. A single representation of a program could be executed on multiple operating systems
3. It should fully support network programming
4. It should execute code from remote sources securely
5. It should be easy to use

Summary

Designed By	Sun Microsystems
Designed In	early 1990s
Basic Aim	For Communicating Between Household things
Earlier Name of Java	OAK
Creator of Java	James Gosling
First Public Release	27 May 1995
Java was targeted at	Internet Development

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