Well, in Java technology an int is a primitive type while an Integer is an Object or wrapper class. Meaning, if you made a new Integer:

Integer integerObj = new Integer(6);

You could call some method on integerObj:

String str = integerObj.toString();
//sets str the string representation of  integerObj

Whereas with an int:

int i = 6;

You can not call any methods on it, because it is simply a primitive. So:

String s = i.toString();//will not work!!!

would produce an error, because int is not an object.

int is one of the primitive type in Java technology. I'm not 100% sure, but I'm thinking that the Integer object more or less just has an int property and a whole bunch of methods to interact with that property (like the toString() method for example). So Integer is a fancy way to work with an int.

Below Example help you to better understand :

package bhagwan;
public class Findnerd{ 
     public static void main(String [] args)  
      {         
       Integer integerObj = new Integer(6);
       System.out.println(integerObj value+integerObj.toString());    
        int i = 6;
        System.out.println(int i value+i);  
      }
 }