Design question

[mac]

Suppose that you have 2 classes you deal with, class A and class B.
Both classes work with Collections and need to make sure that certain data structure contains no duplicates.
Both classes contain methods (slightly different) that take care of it. Method is 1 line long (take blah, return set)

While working fine, from design perspective, i wonder if such an approach is acceptable. Should there perhaps be a class C which contains those methods? The only concern i have- is how prudent it is to create an object of class C inside both A and B for such a small task as gaining access to one method?

Second part of the question extends the scenario a bit. Suppose you have 10 classes A-J, each of which at different times needs to sort, get unique set, format a string ... blah blah blah .. do stuff that does not have anything to do with the main purpose of that class.

Is it acceptable from design perspective to perhaps have a common utils class which in tuen will take care of all of these requests?

Again, in this example object of that class will be created 10 times and called G-d knows how many times. Is this economical?

Thank you.

[m00nchile]

Utility classes usually have static methods, just so you can avoid creating an instance of that class every time you need a small snippet of it's functionallity. So, instead of this:

public class Something {
  ArrayUtils au;

  public void someMethod() {
    au.doSomething(someParameter);
  }
}

you can take the static aproach:

public class Something {
  public void someMethod() {
    ArrayUtils.doSomething(someParameter);
  }
}

So, no istantiation needed. For an example of this, take a look at the Integers parseInt() method. Why would you create an instance of integer, just to get the int value of a String?

[mac]

very cool! Thanks m00nchile