How to convert a class implementing java.lang.Comparable to implement Scala.Ordered?

Question

Is renaming extends Comparable[A] to extends Ordered[A] and renaming def compareTo to def compare enough or is there anything I should take care of?

Rafe Kettler · Accepted Answer · 2010-12-23 14:48:03Z

7

You're correct, that's all you need to do. The other methods in Ordered will use their default implementations, which go as follows:

def <  (that: A): Boolean = (this compare that) <  0
def >  (that: A): Boolean = (this compare that) >  0
def <= (that: A): Boolean = (this compare that) <= 0
def >= (that: A): Boolean = (this compare that) >= 0
def compareTo(that: A): Int = compare(that)

The only thing that doesn't have a default implementation in Ordered is compare, which you'll be defining using your old compareTo method. Should work, provided the above is what you want for your other comparisons.

answered Dec 23, 2010 at 14:48

Rafe Kettler

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