About Java:

Java is developed by Sun Microsystems in 1991 and it is a general purpose language.

Java is a high-level programming language that can be best described by the following keywords.

  • Simple: Compared to other languages like C, C++, java is simple to understand. It is designed to overcome the drawbacks from other languages.
  • Object oriented
  • Distributed
  • Multi-threaded
  • Dynamic
  • Architecture neutral
  • Portable: Java code complied on a windows machine can be run on Unix machine without recompiling it.
  • High performance
  • Robust
  • Secure

Platform independent language:

Platform means an environment (hardware/software) where program runs.

Java is platform independent.

Once code is compiled, it can be run on any platform without the need of recompiling it. WORAWrite Once Run Anywhere.

It is possible with the use of JVM (Java Virtual Machine).


Java Virtual Machine (JVM):

Java source code is stored in a text file with an extention .java

Java compiler compiles the .java code into byte code. Byte code is stored in a file with extension .class

JVM can interpret only the Byte code.

JVM is platform dependent. It varies from platform to platform. But java is platform independent.





A class is a blueprint or prototype that contains variables and methods.


An object is a specimen of a class. It is a group of variables and methods/functions.

Object Oriented Programming:

Features of OOP:

Abstraction: It is the process of extracting the essential information and hiding the irrelevant details.

Inheritance: It is a feature in which one class acquires the properties and functionalities of another class.

Encapsulation: It is a process of binding the code and data as a single unit.