Welcome to the Java Programming Forums
The professional, friendly Java community. 21,500 members and growing!
The Java Programming Forums are a community of Java programmers from all around the World. Our members have a wide range of skills and they all have one thing in common: A passion to learn and code Java. We invite beginner Java programmers right through to Java professionals to post here and share your knowledge. Become a part of the community, help others, expand your knowledge of Java and enjoy talking with like minded people. Registration is quick and best of all free. We look forward to meeting you.
>> REGISTER NOW TO START POSTING
Members have full access to the forums. Advertisements are removed for registered users.
LinkBack URL
About LinkBacks
Transfering Variables across classes.
Class 1:
view sourceprint?
1 public class one {
2 public static void main(String[] args){
3 int num = 0;
4 System.out.println(num);
5 two.change(num);
6 System.out.println(num);
7 }
8 }
Class 2:
view sourceprint?
1 public class two {
2 static void change(int num){
3 num = num + 1;
4 }
}
This should print 0, then 1, but it prints 0, then 0. How do I make it print 0 then 1 with the same format?
Related threads:
Re: Transfering Variables across classes.
That code is very hard to read, but from what I can gather, there is no
instance of class two being created, so your call to:
Should of caused an error. Both classes I am assuming are also in separate source files,two.change(num);
so make sure they each have the same package name so the compiler knows where to find
the methods of each class when they are invoked.
Thirdly, Java does not pass values by reference, only by value. Hence if you passed 'num'
to class two;s method which attempts to increment it by one, the change would happen in
that method, but when control is returned to first method to print out the result, the original
value of 'num' is the same - hence why it is printing zero.
One way around this is to create an array holding the value, and pass that to the method then modify
the index. Array's are passed by reference, class objects by pointer reference.
Wishes Ada xx
If to Err is human - then programmers are most human of us all.
"The Analytical Engine offers a new, a vast, and a powerful language . . .
for the purposes of mankind."
— Augusta Ada Byron, Lady Lovelace (1851)
Re: Transfering Variables across classes.
Welcome to the forum! Please read this topic to learn how to post code in code or highlight tags and other useful info for new members.
Please post your code correctly using code or highlight tags per the above link.
How did you come by this code? Did you just think of it? It's an interesting study that you should play around with to gain a better understanding of how classes and methods work together - or don't. Play with nested classes, static nested classes and inner classes, static/non-static methods, etc. You can find out more about these topics in the Oracle Tutorials.
Re: Transfering Variables across classes.
The change method is static so the code compiles fine. Of course had the OP adhered to naming conventions and called the class Two it would have been easier to read.Originally Posted by Ada Lovelace
Improving the world one idiot at a time!
Reply With Quote