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Treeset Cannot Be Cast To Comparable

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super U, ? extends U> that, BiFunctionCheck This Out

Seems to me a straightforward question. Java is doing the same, e.g. Powered by Blogger. So in that case flatMap(comparator, mapper) has to be called explicitely be the user: treeSet.flatMap(treeSet.comparator(), mapper); I currently can't test it but I think that is the way to go. http://stackoverflow.com/questions/15943031/why-does-treeset-throws-classcastexception

Cannot Be Cast To Java.lang.comparable Treemap

Personal Open source Business Explore Sign up Sign in Pricing Blog Support Search GitHub This repository Watch 75 Star 1,285 Fork 153 javaslang/javaslang Code Issues 87 Pull requests 9 Projects Comparable Check out the comparision and figure out when to use which. current community chat Stack Overflow Meta Stack Overflow your communities Sign up or log in to customize your list. Comparable

Today I had the idea of a lazy comparator. The implementations of Traversable are overloaded there, relying on the RedBlackTree backend, which needs a comparator. Checking for hashCode collisions would be problematic. Java Implement Comparable Think about it for a moment.

TreeSet and TreeMap use sorting for their internal storage. 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 = final class ObjectComparator implements java.util.Comparator, Serializable { private static final long serialVersionUID = 1L; private static final ObjectComparator INSTANCE = new ObjectComparator<>(); private ObjectComparator() { } @SuppressWarnings("unchecked") static ObjectComparator instance() Missing } inserted. \int dx = x + C & Two-way high power outdoor Wi-Fi How does Gandalf end up on the roof of Isengard?

The simplest solution seems to be the best: breaking backward-compatibility :-/ Update/Note: I think also a cycle detection is needed in the solution below (for mutable objects that contain a self-reference Arraylist Is Ordered While Hashset Is Not This looks way too complicated. posted 6 years ago public class Format { public static void main(String args[]) throws Exception { Employee emp1 = new Employee(); emp1.setName("Ravi"); Employee emp2 = new Employee(); emp2.setName("Ravi"); Set set = Laythe Chamse Greenhorn Posts: 15 posted 7 years ago ok, this is my code after solving the comparTo() implementation problem: First Class: import java.util.TreeSet; import java.util.Iterator; public class MyTreeSet { public

  • java collections treemap share|improve this question edited Feb 6 '14 at 2:06 asked Feb 6 '14 at 1:51 Mxt 1115 "So I'm trying to convert a Collection of Strings
  • Because beside T1 and T2 (in your example) there might be also additional types T3, T4, ...
  • Update: Of course this does not make any sense at all (using -1 instead of hash(o1, o2)) because binary search within the tree isn't possible any more.
  • Update 3: o1.hashCode() - o2.hashCode() is not a good solution in general.
  • Exception in thread "main" java.lang.ClassCastException: Employee cannot be cast to java.lang.Comparable at java.util.TreeMap.compare(TreeMap.java:1188) at java.util.TreeMap.put(TreeMap.java:531) at java.util.TreeSet.add(TreeSet.java:255) at TreeSetAddClassCast.main(TreeSetAddClassCast.java:10) To make the program run fine, Employee class must implement the Comparator
  • asked 6 years ago viewed 21558 times active 3 years ago Upcoming Events 2016 Community Moderator Election ends Nov 22 Linked 617 What issues should be considered when overriding equals and
  • posted 7 years ago That's not comparing on two fields, it's basically my ToStringComparator.

Treeset Comparable Example

Should it maybe use the comparator provided in the TreeSet instance? https://coderanch.com/t/461391/java/TreeSet-RuntimeException-code The code for creating the TreeSet with a Comparator is dead simple - there's a constructor that takes a Comparator as an argument: TreeSet tree = new TreeSet(comparator); To create the Cannot Be Cast To Java.lang.comparable Treemap If your objects can not be ordered one way or another, then a TreeSet wouldn't make sense. Cannot Be Cast To Java.lang.comparable Java 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

take(0) and then perend(elem) etc.). his comment is here The static factory methods, e.g. The scan methods look like this: // DEV-NOTE: The return type is either Set or SortedSet, depending whether U is Comparable @Override Set scanLeft(U zero, BiFunction

Comparators are shared between different persistent versions of a collection. TreeSet.empty() et al, could still use the naturalComparator. You can provide a comparator. this contact form super T, ?

I know a HashMap would eliminate this problem, but I have to use a TreeMap. –Mxt Feb 6 '14 at 2:05 Well, if you need a TreeMap (dunno why Comparable Interface Java private Set keyRinger(String current) { Set keyRing = new TreeSet(); for (int i = 0; i < current.length(); i++) { char key = current.charAt(i); keyRing.add(key); } return keyRing; } So my That comparator can't be shared across many trees as the useNatural is specific to a tree.

SCJP 1.4 - SCJP 6 - SCWCD 5 - OCEEJBD 6 - OCEJPAD 6 How To Ask Questions How To Answer Questions Laythe Chamse Greenhorn Posts: 15 posted 7 years

Return true if this set did not already contain the specified element. extends U>> mapper) { return flatMap(naturalComparator(), mapper); } So here it uses a naturalComparator(). public int compare(Object O1, Object O2) { MyOwnClass MyOwnClassX = (MyOwnClass)O1; MyOwnClass MyOwnClassY = (MyOwnClass)O2; return MyOwnClassX.toString().compareTo(MyOwnClassY.toString()); } I extended Comparator interface dont worry. Java Treeset Example Thanks Wouter, it was nice explanation .

HashSet uses equals/hashCode contract instead. Then the resulting SortedSet would be equivalent to an unordered Set. Having no order will result in chaos. http://rinfix.com/cannot-be/treeset-cannot.html Post Reply Bookmark Topic Watch Topic New Topic programming forums Java Java JSRs Mobile Certification Databases Caching Books Engineering Languages Frameworks Products This Site Careers Other all forums Forum: Java in

Terms Privacy Security Status Help You can't perform that action at this time. To be honest, it took me a bit of time to find where the problem was in my code.

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