Question

I wish to design a class to have helper sort of methods on some objects. what is usually the best approach to do so. All the functions will act on these two objects.

SomeObj someObj;
AnotherObj anotherObj;

public SomeClass(SomeObj someObj,AnotherObj anotherObj){
this.someObj=someObj;
this.anotherObj=anotherObj;
}

somefunction(){
//act on the instance vars
}

or should I have simple class with no instance vars (stateless) and make function to accept the required variables

public SomeClass(){

}

somefunction(SomeObj someObj,AnotherObj anotherObj){
//act on the local vars
}

Which approach is considered good in terms of design.

Answer 1

If the only method that will act on the SomeObj and AnotherObj objects is someFunction() then they probably dont need to be stored as instance vars. If they will be used/needed to modify the state of SomeClass from someFunction() and other internal methods, then I would say that they should indeed be stored.

You could consider a few alternatives regarding the SomeClass class implementation:

• If it wont have any state, then the methods should probably be static
• Depending on how complex the operations are and how many helper methods you will have, you could use a Visitor design pattern