Public Object: Coding in the small with Google Collections: Comparators.max

Coding in the small with Google Collections: Comparators.max

Part 3 in a Series.

Comparators.max takes two Comparables and returns the larger of the two. It improves upon the standard approach, which requires both a comparison and a ternary:

Before:

public Money calculateDeliveryCharge(Order order) {
   double distanceInKm = Geography.getDistance(
       storeAddress, order.getAddress());
   Money perKm = pricePerKm.times(distanceInKm);
  
   return perKm.compareTo(minimumDeliveryCharge) > 0
       ? perKm
       : minimumDeliveryCharge;
 }

After:

  public Money calculateDeliveryCharge(Order order) {
   double distanceInKm = Geography.getDistance(
       storeAddress, order.getAddress());
   Money perKm = pricePerKm.times(distanceInKm);

   return Comparators.max(perKm, minimumDeliveryCharge);
 }

Of course the Comparators.min method is also included. As a special treat, there's overloaded versions of each that allow you to specify your own comparator, such as String.CASE_INSENSITIVE_ORDER.

Part 4

# posted by Jesse Wilson on Saturday, September 08, 2007

There is a small error in your post. You used the class name "Comparables" instead of the correct class name "Comparators".

# posted by William on October 17, 2007 3:08 PM

Thanks! Fixed.

# posted by swankjesse on October 18, 2007 12:26 AM

sweet!!!

# posted by technophilos on October 28, 2007 12:46 PM

There're some "Comparables" yet.

# posted by Anonymous on December 26, 2007 7:30 AM

Fixed; how embarrassing.

In other news, the 'new' new way to do this with Google Collections is even simpler with the Ordering base class. It lets you do stuff like this:
Date payday = ...
Date weekend = ...
Date party = Comparators.naturalOrder().min(payday, vacation);

# posted by swankjesse on December 27, 2007 12:05 AM