Why the compiler is not throwing the error when I use integer wrapper class ?

See more:

Java

Java8

int phoneNumber = m.get(s);
            if(phoneNumber!=null)
                {
            System.out.println(s + "=" + phoneNumber);
            }

This code returns the following error statement (obviously)

error: incomparable types: int and <null>

             if(phoneNumber!=null)
                             ^

But this code works fine if I use a wrapper class.

Integer phoneNumber = m.get(s);
                if(phoneNumber!=null)
                    {
                System.out.println(s + "=" + phoneNumber);     
                }

What I have tried:

Why the compiler is not throwing the incomparable types error here ?