Difference between Instance Variable and Local Variable

A variable is a name given to a memory location. It is the basic unit of storage in a program.

• The value stored in a variable can be changed during program execution.
• A variable is only a name given to a memory location. All the operations are done on the variable effects of a memory location.
• In Java, all the variables must be declared before use.

Instance Variable: These variables are declared within a class but outside a method, constructor, or block and always get a default value.

• These variables are usually created when we create an object and are destroyed when the object is destroyed.
• We may use an access specifier, for instance, variable, and if no access specifier is specified, then the default access specifier is used.
• Each and every object will have its own copy of instance variables.

Example:

class Taxes  
{  
   int count; // Count is an Instance variable  
   /*...*/  
}  

Local Variable: These variables are declared within a method but do not get any default value.

• They are usually created when we enter a method or constructor and are destroyed after exiting the block or when the call returns from the method.
• Its scope is generally limited to a method and its scope starts from the line they are declared. Their scope usually remains there until the closing curly brace of the method comes.
• The initialization of the local variable is mandatory.

Example:

int area()      
{    
        int length = 10; // Local variable          
        int breadth = 5; // Local variable          
        int rectarea = length*breadth; // Local variable          
        return rectarea;          
}  

Tabular difference between the instance variable vs local variable: