What is the difference between an int and an Integer in Java and C#?

Question

I was reading More Joel on Software when I came across Joel Spolsky saying something about a particular type of programmer knowing the difference between an i

Answer 1

(Java Version) In Simple words int is primitive and Integer is wrapper object for int.

One example where to use Integer vs int, When you want to compare and int variable again null it will throw error.

int a;
//assuming a value you are getting from data base which is null
if(a ==null) // this is wrong - cannot compare primitive to null
{
do something...}

Instead you will use,
Integer a;
//assuming a value you are getting from data base which is null
if(a ==null) // this is correct/legal
{ do something...}