A class with only static methods?
If I have a class with only static methods, that are just changing values of instance variables and returning some values to calling methods, is there a need for a constructor? Will one ever be called because I will never create an object of this class and will only call these methods to retrieve values needed elsewhere. In addition, if the methods are all static, does the class need to be declared in any special way? Also, how can I reset all of the instance feilds of this class? Can I just write another static method that will set the instance variables to the desired values?
Or am i going about this the wrong way? I am very new to OOP.
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woohoo1a] at [2007-10-2 14:00:56]
> that are just changing values of instance variables
> and returning some values to calling methods,
To me, this smells wrong. Maybe a Singleton, or just a standard object.
> is there a need for a constructor?
In the design you have outlined (its not OOM, but what the hell), I would have a no-arg private ctor, so no one could created an instance of the none-object.
> Will one ever be called because I will never create an object of this class
No, if you don't create an object, a ctor is not called, but someone else could (as Java will add a public no-arg ctor, unless you have a ctor).
> In addition, if the methods are all static, does the
> class need to be declared in any special way?
No
> Also, how can I reset all of the instance feilds of this class?
As I said this smells wrong, but without knowing what you are up do, I can't say what to change it with. But yes, from how you have described, a "reset" method would be fine.
> Or am i going about this the wrong way? I am very new to OOP.
I'd say yes, but without knowing more I can not give an alternative.
mlka at 2007-7-13 12:07:43 >
If your class only has static methods, there is no need for instance
variables, because there is no use for them cf. the System class.
I you want to protect your class from having any instance being created
implement a private default constructor:public YourClassWithStaticMethods {
private YourClassWithStaticMethods() { }
...
}
With this private ctor, explicitly implemented by you, the compiler is not
allowed to implement one for you. The class can also not be extended
because of this private ctor.
kind regards,
Jos
JosAHa at 2007-7-13 12:07:43 >
> returning some values to calling methods, is there a
> need for a constructor? Will one ever be called
Not a NEED. But to really be correct you should make a constructor like
private MyClass() {}
which will make it totally uninstantiatable.
> all static, does the class need to be declared in any
> special way? Also, how can I reset all of the
Nope. You don't need a special declaration although you might want to add some javadoc comments
> instance feilds of this class? Can I just write
Do you mean instance fields or static fields? Hopefully static fields as you'll never have an instance and thus no instance fields
> another static method that will set the instance
> variables to the desired values?
Sure you could do this
Well I think the use of all static classes are not bad design if you use it properly. It usually good for utilities and Factory classes, For example Math, Collections, BorderFactory etc
> Well I think the use of all static classes are not
> bad design if you use it properly. It usually good
> for utilities and Factory classes, For example Math,
> Collections, BorderFactory etc
Yes, all static methods are fine in the there place. But normally they don't have variables.
mlka at 2007-7-13 12:07:43 >
