When should null values of Boolean be used?

Question

Java boolean allows values of true and false while Boolean allows true, false, and null. I have

Answer 1

Main purpose for Boolean is null value. Null value says, that property is undefined, for example take database nullable column.

If you really need to convert everyting from primitive boolean to wrapper Boolean, then you could use following to support old code:

Boolean set = Boolean.FALSE; //set to default value primitive value (false)
...
if (set) ...