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 ahywhere 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:
![local variable.jpg]()
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:
![class variable.jpg]()
Summary
This article will introduce you to the various types of variables in Java and their properties.