Question

If I have a method that is to return a TreeSet of integers how should I declare it?

Option A

public Collection returnSortedIntegers()

Option B

public Set returnSortedIntegers()

Option C

public Set<Integer> returnSortedIntegers()

Option D

public TreeSet<Integer> returnSortedIntegers()

---

The reason I ask is because I was getting the -Xlint:unchecked message when I compiled a class that used this method in one of it’s methods. I had no problems compiling it when it looked like Option A, it was only when I compiled the different class that used the method that I got the xlint message which is why I have changed it to Option C and the message has gone away.

---

Thank you for your answers, it would appear that this is winning

Option E

public SortedSet<Integer> returnSortedIntegers()

I am studying Java at the moment so it’s quite new to me and I wasn’t aware of the SortedSet interface, I was only aware that TreeSet was a subclass of Set. As always Stack Overflow has enlightened me.

Answer 1

Option E:

public SortedSet<Integer> returnSortedIntegers()

This is giving the caller the minimum information they need to know about what is returned while still being helpful:

• It is a Set
• It contains Integer
• It is sorted