Introduction to Java

Part 1 Contents :

•     History of Java
•     What is JDK
•     Features of Java
•     Sample program 

History of Java

Java is Object oriented, Multi-threading language developed by Sun Microsystems in 1991.

It is designed to be small, simple and portable across different platforms as well as OS.

What is JDK

JDK stands for Java development Kit.

There are two parts: Java Compiler and Java Interpreter (JVM).

Java Compiler generates bytecode instead of machine code and interpreter executes java

program. 

What is bytecode?

Bytecode is a set of instructions that resemble machine code but are not specific to any

processor.

The disadvantage of using bytecode is the execution speed. Since system specific programs

run directly on the hardware, they are faster than the Java bytecode. 

Features of Java

1. Syntax based on C++
2. Object-oriented
3. Support for Internet applications
4. Extensive library of prewritten classes
5. Portability among platforms
6. Built-in networking
7. Security as JRE is inaccessible to other parts of computer. 

Class 

• Tool for encapsulating data and operations (methods) into one package
• Defines a template or model for creating and manipulating objects

• Data created using the class and its methods
• An object is an instance of the class
• Creating an object is instantiation

• Well-written classes can be reused in new applications
• Shortens development time because programmers don’t need to write new code
• Programs are more robust because the class code is already tested