booleanValue();

[Netty poestel]

public class BoolTest {
2. public static void main(String [] args) {
3. Boolean b1 = new Boolean("false");
4. boolean b2;
5. b2 = b1.booleanValue();
6. if (!b2) {
7. b2 = true;
8. System.out.print("x ");
9. }
10. if (b1 & b2) {
11. System.out.print("y ");
12. }
13. System.out.println("z");
14. }
15. }

what is the result ?

Now the answer given is :-

E. The compiler fails at line 10 because b1 is a reference variable to a Boolean wrapper object, not a boolean primitive.[ which is absolutely Fine.]

My question is :- I thought line 5 [ aka b2 = b1.booleanValue(); ]
should have been the culprit, since there is nothing like a 'booleanValue'.
I ran the above code , and the compiler prooves me wrong( absolutely Fine here too )... but why ?
TIA

[Toms Liepins]

Hi,
Could you please explain what you mean with "since there is nothing like a 'booleanValue'". I'm afraid I don't get that one

Line 5 is absolutely legal - you call the booleanValue() function on Boolean object (this function returns boolean primitive), and then you assign the return value to another boolean primitive b2.

You might want to look up the Boolean class in Java API Docs for more info on booleanValue() function.

[Joe Borderi]

Boolean (Class) Method Summary:

boolean booleanValue()
Returns the value of this Boolean object as a boolean primitive

[Netty poestel]

whoa!
since I was on the wrapper chapter, seeing booleanValue() I assumed that this has to do with the xxxValue() conversion utility.
and in the Common Wrapper Conversion Methods the only methods available for this are "byteValue,doubleValue ,floatValue ,intValue ,longValue ,shortValue"

but it seems the reply given is again "news for me"

[marc weber]

Note that Byte, Short, Integer, Long, Float, and Double all extend Number, which contains the six numeric xxxValue() methods.

http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Number.html

Boolean and Character do not inherit from Number. So booleanValue() and charValue() are unique to their respective wrappers.

[Barry Gaunt]

Originally posted by Netty poestel:
whoa!
since I was on the wrapper chapter, seeing booleanValue() I assumed that this has to do with the xxxValue() conversion utility.
and in the Common Wrapper Conversion Methods the only methods available for this are "byteValue,doubleValue ,floatValue ,intValue ,longValue ,shortValue"

but it seems the reply given is again "news for me"

Don't "assume" anything. When you are learning something new about Java read the Java API in conjunction with your book. And at least try to understand what the Java Language Specification says about it (for the basics).