Variable Types in Java

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Variable Types in Java

Introduction

A variable specifies a memory location that contains data. The data can be numbers, characters and so on. There are three types of variables in Java:

Local variables
Instance variables
Class variables

Local variables

A method uses local variables for storing its temporary state.
Generally, these are declared inside the methods, constructors or blocks of code.
These should always be declared and initialized before their use.
We cannot access local variables anywhere other than the specific methods, constructors or blocks of code in which they are declared.
When the method is executed completely, these local variables are destroyed.

Example:

package myclass1;
class Myclass1 {
public void classStrength() {
int strength = 100;
strength = strength - 10;
System.out.println("Class strength is : " + strength);
}
public static void main(String args[]) {
Myclass1 count = new Myclass1();
count.classStrength();
}
}

Output:

Instance variables

These are also known as non-static variables.
These are declared inside a class, but outside a method, constructor or a block of code.
Instance variables have a default value.
These are created and destroyed when the object is created and destroyed respectively.
Inside the class these can be accessed directly by calling their names.
Instance variables can be accessed by all methods, constructors or blocks of code in the same class.

Example:

package myclass1;
class Myclass1 {
public String location;
private int id;
public Myclass1(String Location) {
location = Location;
}
public void id(int classid) {
id = classid;
}
public void Location() {
System.out.println("Location : " + location);
System.out.println("id :" + id);
}
public static void main(String args[]) {
Myclass1 scl = new Myclass1("ndl");
scl.id(10090);
scl.Location();
}
}

Output:

instance variable.jpg

Class variables

These are also known as static variables.
These are declared inside a class with a static keyword, but outside a method, constructor or a block of code.
These variables are created and destroyed when the program starts and ends respectively.
Class variables also have a default value.
These variables can be accessed just by referring to them with the class name.

Example:

package myclass1;
class Myclass1 {
private static int rollno;
public static final String CLASS = "class topper";
public static void main(String args[]) {
rollno = 10;
System.out.println(CLASS + " roll no is :" + rollno);
}
}

Output:

Summary

This article will introduce you to the various types of variables in Java and their properties.