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In a compareTo method the problem gets worse because dates do not sort correctly when you sort them alphabetically. super T, ? I'm afraid I find free time to fix them in a short time. share|improve this answer answered Feb 6 '14 at 2:04 Sotirios Delimanolis 156k25258371 So a custom Comparator would be a seperate method? Check This Out

Comment 3 Peter Nabbefeld 2011-09-19 09:46:16 UTC Don't know, if it really belongs to contrib - the problems where shown in MMR first, but seem to cause a number of additional If you're still confused read this. "Any fool can write code that a computer can understand. Possible repercussions from assault between coworkers outside the office What is the significance of the robot in the sand? I think the hash(o1, o2) method is a good solution as fallback for non-equal objects. (see also notes below) final class ObjectComparator implements java.util.Comparator, Serializable { private static final long serialVersionUID

Treeset Comparable Example

Problem starts when I add second element. So, am I totally misusing the TreeSet? posted 6 years ago The TreeSet orders it's elements. extends U> that, T thisElem, U thatElem); @Override SortedSet> zipWithIndex(); @Override SortedSet zipWithIndex(BiFunction

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  • Technically we assume that the hashCode of an object corresponds to the memory address of the object.
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  • Otherwise TreeSet can't function since it wouldn't know how to order the elements.
  • To correct this issue, you should create a TreeMap by providing your own custom Comparator for comparing Set instances.

You may want to use a HashSet instead, which have its own contracts. MathSciNet review alert? I need to check if there are benefits when we make the instance variable volatile. Treeset Example In Java Any other thoughts?

The easiest way to achieve that is to let your equals method call the compareTo method and check if the result is 0. You would have had the same error when using these objects in a TreeMap, or when they were in a List and you sorted it using Collections.sort(List). When you have one element there is nothing to compare so it doesn't detect the problem. I agree that the reflection is some intense code smell though.

Sponsored by Cookies help us deliver our services. Arraylist Is Ordered While Hashset Is Not For TreeSet, you either have to make the elements Comparable, or provide a Comparator. Join them; it only takes a minute: Sign up List to TreeSet conversion produces: “java.lang.ClassCastException: MyClass cannot be cast to java.lang.Comparable” up vote 11 down vote favorite 2 List myclassList = extends V> m) { return new TreeMap(m); } // not too sure if this is guaranteed to be safe...Apart from not being able to create a TreeSet without a Comparator, it

Java Lang Classcastexception Cannot Be Cast To Java Lang Comparable Treemap

We can't check the special case where T is U. http://www.programcreek.com/2009/02/implement-comparable-for-a-treeset/ Thanks for the kind words :-) Daniel benoitheinrich commented Mar 24, 2016 Hi @danieldietrich, Thanks for the quick answer !! Treeset Comparable Example super K> k = (Comparable

Also we can't take the naturalComparator by default and fall back to the unordered comparator because we would have internally to catch a ClassCastException which takes too much time. We are mapping to elements of type U, therefore we need a new comparator. Because of type erasure we are not a able to inspect the runtime element type of a collection. Most outdated modules are disabled because of missing dependencies, so this shouldn't hurt. Treeset Comparator Duplicates

And why are you using a TreeMap instead of HashMap? –user2357112 Feb 6 '14 at 1:53 I'm not really sure why you need reasons for what objects I'm using, So your key element in your TreeMap must implement Comparable. import java.util.TreeSet; class Dog { int size; Dog(int s) { size = s; } } public class ImpComparableWrong { public static void main(String[] args) { TreeSet i = this contact form super K>,V> create() { return new TreeMap(); } public static create(Comparator

We recommend upgrading to the latest Safari, Google Chrome, or Firefox. Java Implement Comparable You were comparing the date-or-birth by first calling toString. Previous examples of large scale protests after Presidential elections in US?

This is spelled out in the documentation for SortedSet: All elements inserted into a sorted set must implement the Comparable interface (or be accepted by the specified comparator).

super T, ? That allows me to technically create a SortedSet implementing class which uses the system hash code for ordering. Set s = new TreeSet(); s.add(new Employee(1001)); Or Set s = new HashSet(); s.add(new Employee(1001)); s.add(new Employee(1002)); Then result is success there is no exception. How Treeset Works Internally In Java TreeSet.empty() et al, could still use the naturalComparator.

super K>,V> create(Mapnavigate here Thank You for fixing the bug!

If there are modules from different builds, the spec versions probably have never been updated, so AU doesn't work correctly. To make an object comparable, user-defined class must implement the Comparable interface. 2. How would I call that in this code? –Mxt Feb 6 '14 at 2:11 @Mxt Comparator is an interface. Then the resulting SortedSet would be equivalent to an unordered Set.

posted 7 years ago What do you mean by "the same time"? You can either let Employee implement the Comparable interface or provide an appropriate Comparator for your TreeSet: Set s = new TreeSet(new EmployeeComparator()); share|improve this answer edited Apr 11 '13 at LinkedHashSet A simple TreeSet example Comparable vs. I think it can be deleted.

Perhaps something like what @benoitheinrich proposed, but with additional constraints where in a.compareTo(b) b must be an instance of a.getClass(). What do I do? extends V> m) { return new TreeMap(m); } public static create(SortedMap

Status: RESOLVED FIXED Product: contrib Classification: Unclassified Component: Module Manager Version: 7.1 Hardware: All All Priority: P2 (vote) TargetMilestone: 7.2 Assigned To: Jiri Rechtacek QA Contact: issues@contrib URL: Whiteboard: EXCEPTIONS_REPORT Keywords: Wouter Oet Saloon Keeper Posts: 2700 I like... Browse other questions tagged java set treeset or ask your own question.

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