Java Variables

Variables are the identifier of the memory location, which used to save data temporary for later use in the program.

Variable Definition in Java

Syntax:

type variable_name;

type variable_name, variable_name, variable_name;

Example:

/* variable definition and initialization */
int    width, height=5;
char   letter='C';
float  age, area;
double d;

/* actual initialization */
width = 10;
age = 26.5;

Variable name need to be chosen by the programmer in a meaningful way so that it reflects what it is representing within a program.

Rules of Declaring variables in Java

• Variable name can consist of Capital letters A-Z, lowercase letters a-z, digits 0-9, and two special characters such as underscore and dollar Sign.
• The first character must be a letter.
• Blank spaces cannot be used in variable names.
• Java keywords can not be used as variable names.
• Variable names are case-sensitive.

Types of Variables in Java

There are three types of variables in Java:

• Local variables
• Instance variables
• Class/Static variables

Local variables

A variable that is declared within the method that is called local variables.

Instance variables

A non static variable that is declared within the class but not in the method is called instance variable.

Class/Static variables

A variable that is declared with static keyword in a class but not in the method is called static or class variable.

Example:

class A {
 int amount = 100; //instance variable  
 static int pin = 2315; //static variable 

 public static void main(String[] args) {
  int age = 35; //local variable  
 }
}

Example:

public class Example {
 int salary; // Instance Variable

 public void show() {
  int value = 2; // Local variable
  value = value + 10;
  System.out.println("The Value is : " + value);
  salary = 10000;
  System.out.println("The salary is : " + salary);
 }

 public static void main(String args[]) {
  Example eg = new Example();
  eg.show();
 }
}