Java autoboxing and ternary operator madness

Question

Just spent a frustrating couple of hours debugging this code:

    LinkedHashMap rsrqs = new LinkedHashMap();
           


        

Answer 1

1

is an int, not an Integer. So, Java is going to un-box your Integer to int, which causes the NullPointerException. When you auto-unbox a null Integer, it results in a NullPointerException. ( reference here )

But when you use

 Integer.valueOf(-1) 

it doesn't need to auto-unbox it, which leads to no exceptions.