Compares two values and returns a number having the same relative value to zero.

Compare will return a number

• less than zero if the left is less than the right
• more than zero if the right is more than the left
• equal to zero if the left is either incomparable or equivalent to the right

Object.compare delegates to compare methods of objects when they are available, and returns 0 if neither the left or right object support comparison.

When comparing numbers, compare returns the difference between the left and right, which expresses both the direction and magnitude of the relative values. If the magnitude of the difference is not meaningful, compare should return only Infinity, -Infinity, or 0, but there is a long established precedent from C of returning -1 and 1 instead.

Note that comparison is not sufficient to distinguish equality, since 0 can mean that the values are incomparable.

The optional second argument is an alternate comparator to use on the content of the left collection, and defaults to Object.compare.

On collections

• List
• Deque
• SortedArray
• SortedArraySet
• Array
• Object
• GenericOrder