GNS | Java Classes

Java : Creating a Custom Class

Overview

If you are familiar with creating classes in C/C++, I have some good news and some bad news...

Good news: The concept of classes is the same in every OOP language, so you're at least one step ahead of new programmers.

Bad news: The syntax you used in C/C++ is different enough that you're probably going to spend a lot of time cursing at the Java compiler...

Similiarities

Java is loosely based on C++, and implements OOP is more or less the same way. You can implement your code logic (say, from psuedocode or UML diagrams) without much trouble, even if it was developed with specific C++ libraries in mind, as an equivalent library is probably available in the JRE (Java Runtime Environment).

Differences

While Java takes quite a bit of its base syntax from C and C++, it IS a different language, with its own quirks and strengths. One of the things that confused me when I first started to learn Java was the keywords it uses for its class structure. For instance, instead of namespace, Java uses package. Instead of inherits, you get extends.

Take a gander at this sample I put together for you:

• SampleClass.java


					class SampleClass

					{

					   public SampleClass( 
					void ) // constructor

					   {

					   /* place code here that needs to execute

					   when an instance of our class is created */

					   }

					

					   
					// private internal variables and functions go here

					   private int age;

					   private char[] name = 
					new char[50];

					

					   /* public shared variables and external functions

					   go here */

					   public int GetAge( 
					void )

					   {

					     return age;

					   }

					

					   public void SetAge( 
					int value )

					   {

					     age = value;

					   }

					}