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Java Forum / First Aid / February 2005difference between comparator and comparable interface
what's the difference between comparable and comparator interface. > what's the difference between comparable and comparator interface. Comparable interface shows that the class knows how to compare ITSELF against another class. Comparator interface allows a single class know how to compare two classes which (typically) are not the same type as the comparator. Its about moving the responsibility for doing the comparison from the class that is being compared, to another class who's sole responsibility is to be the comparator. > what's the difference between comparable and comparator interface. Something that's Comparable knows how to compare itself to others (presumably of the same class). How it does so is built into the class. For example, Strings compare themselves alphabetically (well, by character value, anyway). A Comparator can compare two other objects by whatever criterion the Comparator chooses. For example, it might compare Strings by their length. HTH, Michiel In comp.lang.java.help Michiel Konstapel <usenet@konstapel.nl> wrote: >> what's the difference between comparable and comparator interface. > [quoted text clipped - 4 lines] > criterion the Comparator chooses. For example, it might compare Strings by > their length. The Comparable interface is (IMO) best used to implement a natural order for lists of elements of the class. For example the low-to-high order of numbers represented by the Integer class. This ties in nicely with the order used by the variants of TreeSet, TreeMap, Arrays.sort() and Collections.sort() where no Compataror is specified. The Comparator interface is then used to create exotic orders, where exotic is anything not implemented by the Comparable interface. This also means the most obvious order for elements if a class doesn't implement Comparable, though a subclass may sometimes be a better choice then.  SignatureOscar Kind http://home.hccnet.nl/okind/ Software Developer for contact information, see website PGP Key fingerprint: 91F3 6C72 F465 5E98 C246 61D9 2C32 8E24 097B B4E2 Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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