Variables in Java

Variables in Java

A variable is a name given to a memory location. It is the unit of storage in the program. The value stored in a variable can be changed during program execution.

For example- int a;   // where int is data type and a is variable

Java variables type:

Local variable

Instance variable

Static variable

Local variable:

A local variable is declared inside the body of the method is called the local variable. A Local variable cannot be defined with a static keyword. No object requires to access the Local variable. The scope of these variables exists only within the method in which variable the variable is declared.

Instance variable:

An instance variable is declared inside the class but outside the body of the method is called the Instance variable. It is not declared with the static keyword. These variables are accessed through the object of the class. 

Static variable:

A static variable is declared inside the class but outside the body of the method with the static keyword is called Static variable. It is similar to the instance variable but the difference is the static variable declared with the static keyword while the instance variable declared without the static keyword.

Sample program:

public class Variables{

static int a=10; // static variable

int b=20;  // Instance variable

public static void main(String args[]){

int c=30;  //Local variable

System.out.println("static variable is:"+a);

System.out.println("local variable is:"+c);

Variables obj=new Variables(); //object created for instance variable

System.out.println("instance variable is:"+obj.b);

}

}

For instance, variable if we do not create an object it gives an error. Let's see

public class Variables{

static int a=10;

int b=20; // In this program no object create for instance variable

public static void main(String args[]){

int c=30;

System.out.println("static variable is:"+a);

System.out.println("local variable is:"+c);

System.out.println("instance variable is:"+b);

}

}

Arrow mark show error when no object create for instance variables