Core Java

Introduction:

An Object Oriented Programming Language consists of Objects. There are object oriented programming languages like Smalltalk, C++. Each and every OOP language has some underlying disadvantages. C++ has some disadvantages like Security, Robust and Platform dependent. All these disadvantages make C++ inappropriate choice for developing a secured we application. To overcome all these disadvantages, James Gosling came up with a programming language “Java” in 1995 in Sun Microsystems. There are many advantages of Java as a programming language. They are Portable, Secured, Reliable, Robust, Platform Independent etc.

1. Portability:

Portability is an advantage of Java. This is a feature which makes Java to be used in various devices like mobiles, PCs etc. An application that is developed for pc can also be used in mobiles as android application.

2. Secured:

Using Java, we can develop secured web applications. In Java, we have security features that help us develop secured applications.

3. Reliable:

Java as a programming is more reliable. Reliability means an application developed in Java executes more reliably using security, class loader mechanism etc.

4. Platform Independent:

This is the most important feature of Java. It works mainly on the principle of wora (write once run anywhere). Whenever we write a Java class and compile that class, a .class file will be created. The JVM installed in a machine convert this .class file into machine specific code. This machine code is called machine language. It is interpreted and executed leading program output. That’s why in most cases, the coding is done in one system (windows) and deployment is done in another (Linux).

5. Software requirements:

• Windows/Linux OS.

• JDK (any version).

• Any Application Server/Web Server (For Web Applications).

• Installation.

• Install JDK.

• Setting variables.

The following variables are to be set:

• Path and/or JAVA_HOME

• OOPS

In Java, OOPS principles form the main pillars. They are Abstraction, Polymorphism, Inheritance and Encapsulation.

1. Abstraction:

Abstraction is an OOPS principle where the main focus will be only on the functionality hiding the implementation details. In java, abstraction can be achieved by using abstract classes and interfaces. A buyer will be looking only for some basic things like no of seats, space etc. The salesman will not tell about the internal working of the car.

2. Polymorphism:

Polymorphism is an OOPS principle where a method exhibits different behaviours. There are two types of Polymorphism. Method Overriding and Method Overloading. Method Overriding is method having same name type, same parameter list both in super class and sub class. Method overloading is multiple methods with same as long as the parameters are differing.

3. Inheritance:

Inheritance is another OOPS principle where subclasses inherit properties from Super class. Properties means both data members and data variables. Dog inherits properties from Animal class.

4. Encapsulation:

Encapsulation is binding data members and data variables in a single unit called object. When a class is defined and an object is created for that class, each object will have its own copy of data members and data variables.