wood burning stoves 2.0*
The moose likes Beginning Java and the fly likes question about this code Big Moose Saloon
  Search | Java FAQ | Recent Topics | Flagged Topics | Hot Topics | Zero Replies
Register / Login

Win a copy of Murach's Java Servlets and JSP this week in the Servlets forum!
JavaRanch » Java Forums » Java » Beginning Java
Bookmark "question about this code" Watch "question about this code" New topic

question about this code

Larry Lai
Ranch Hand

Joined: May 13, 2002
Posts: 44
Hi everyone,
why this code has a "?"
radius= (circleRadius>=0.0? circleRadius:0.0);


Ken Cobbs

Joined: Jun 18, 2002
Posts: 29
Sorry about that blank post. Tyring to figure out how to make a post.
Any way, I believe that the '?' your asking about is like putting an 'if' statement in the middle of an expression. The example I see in 'Just Java2' 5th edition gives an example on page 131.
radius = ( circleRadius >= 0.0 ? circleRadius : 0.0 );
would mean that circleRadius would be evaluated if it 's >= 0.0 (true) and 0.0 if it's not >= 0.0(false).
My first post. Hope I didn't confuse 'ya.
Barry Gaunt
Ranch Hand

Joined: Aug 03, 2002
Posts: 7729
Ken, you can delete the dead post via the edit icon.
The expression "boolean expression" ? "true alternative" : "false alternative" has been inherited from C/C++.
If "boolean expression" is true then the result of the expression is the result of the "true alternative" expression, else it is the result of the "false alternative" expression. The type of the result expression is the "widest" of the types of the two alternatives.
So true ? 9 : -1.0 will result in 9.0 (a double) being returned, and false ? 9 : -1.0 will result in -1.0 (also a double) being returned.
Its a bit tricky so look this up in your Java books because it can appear in Java Certification exams.

Ask a Meaningful Question and HowToAskQuestionsOnJavaRanch
Getting someone to think and try something out is much more useful than just telling them the answer.
Larry Lai
Ranch Hand

Joined: May 13, 2002
Posts: 44
Hey Barry,
Thanks a lot
I understand it now.
Ken Cobbs

Joined: Jun 18, 2002
Posts: 29
Thanks Barry,
I'll get this posting down(sometime).
It is sorta covered in the JavaRanch Style Guide.
subject: question about this code
Similar Threads
Programing challenge
Circle program errors
Help with Circle Class :)
Object Arrays