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Accessing variables in foreign class ...  RSS feed

 
Greenhorn
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Say you have a method in ClassA which returns a number based on a private variable, e.g.:
//The Number variable
private int myNumber;
// skip code ...
//The method
public void returnMyNumber(){
return myNumber;
}
How would you go about accessing the number variable from ClassB? Something like:
// Return classA variable
public void returnClassAVariable(){
return ClassA.myNumber;
}
Any ideas?
 
Jack Weavesham
Greenhorn
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& thinking about it, how could you test that the ClassA myNumber variable equals a ClassB variable?
 
author
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Originally posted by Jack Weavesham:
Say you have a method in ClassA which returns a number based on a private variable, e.g.:
//The Number variable
private int myNumber;
// skip code ...
//The method
public void returnMyNumber(){
return myNumber;
}
How would you go about accessing the number variable from ClassB? Something like:
// Return classA variable
public void returnClassAVariable(){
return ClassA.myNumber;
}
Any ideas?


As ClassA.myNumber is an *instance* variable, you can't access it without having an instance of ClassA. And once you had, you'd just use the getter method:

Notice though that this (especially the naming) seems to suggest a design problem: a classes interface should generally be about its behaviour, not about its internal data.
 
Ilja Preuss
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Originally posted by Jack Weavesham:
& thinking about it, how could you test that the ClassA myNumber variable equals a ClassB variable?


Can you please give a more complete example of what you'd want to do - and why? Thanks!
 
Jack Weavesham
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The idea is just a sample class structure to learn from. As an overall idea : how could you add a private variable in ClassA (for example) to a private variable in ClassB?
 
Ranch Hand
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so what you are wondering Jack, is how to assign what is returned to a variable in Class B, and somehow add that to a private variable, as an excersize?
hmm interesting
ps - i know it's just an excersize, but in terms of the tenets of OO programming and encapsulation, i think private variables are meant to not be shared around? of course, it would be possible. just an idea.
[ January 11, 2003: Message edited by: Jasper Vader ]
 
It is sorta covered in the JavaRanch Style Guide.
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