This week's book giveaway is in the General Computing forum. We're giving away four copies of Arduino in Action and have Martin Evans, Joshua Noble, and Jordan Hochenbaum on-line! See this thread for details.
Integer is a wrapper of the primitive type int.The wrapper classes are basically used in cases where you want to treat the primitive as an object for ex-trying to pass an int value in a method that would take only a type of Object in such a case you would want to wrap primitive int value in the wrapper Integer which is of type Object. To know specific advantages of Integer I would suggest you to take a look at the Integer api provided by Sun.