Question

I am looking through code and wondering what this means:

Boolean foo = request.getParameter("foo") == null? false:true;

It’s gotta be something that converts the returning String from getParameter() into a Boolean.

But I’ve never seen this kind of Java with a questionmark and colon (except in a foreach loop).
Any hel appreciated!

Answer 1

It’s the ternary operator. The snippet:

Boolean foo = request.getParameter("foo") == null? false:true;

is equivalent to:

Boolean foo;
if (request.getParameter("foo") == null)
    foo = false;
else
    foo = true;

or (optimised):

Boolean foo = request.getParameter("foo") != null;

The basic form of the operator is along the lines of:

(condition) ? (value if condition true) : (value if condition false)