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Java.lang.classcastexception Cannot Be Cast To Java.lang.comparable Treemap

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What do I do? You signed in with another tab or window. I agree that the reflection is some intense code smell though. Removing any of the constructors was not an option as it would break older code. news

share|improve this answer edited Apr 11 '13 at 7:43 answered Apr 11 '13 at 7:35 Francisco Spaeth 15.2k33671 add a comment| up vote 0 down vote TreeSet is an implementation of Already have an account? MyOwnClass must implement Comparable. [My Blog] All roads lead to JavaRanch Laythe Chamse Greenhorn Posts: 15 posted 7 years ago I implemented Comparable interface and it's compareTo() Method to MyOwnClass, extends E> c) { return new TreeSet(c); } public static create(SortedSet s) { return new TreeSet(s); } // not too sure if this is guaranteed to be safe...public static

Cannot Be Cast To Java.lang.comparable Treeset

Now the tricky thing is that when you assign your TreeSet to a Set type, then the flatMap(comparator, function) method isn't available anymore. Join them; it only takes a minute: Sign up What causes the ClassCastException: java.util.TreeSet cannot be cast to java.lang.Comparable? Here is the example: public class TreeSetTest { @Test public void testFlapMap() { final TreeSet objs = TreeSet.ofAll((o1, o2) -> o1.field.compareTo(o2.field), Stream.of("o1", "o2").map(Obj::new) ); // That works as you're using a

What do I do? FasterXML, LLC member cowtowncoder commented Jul 5, 2013 Ok good that it works. Should I report it? Cannot Be Cast To Java.lang.comparable Priority Queue kdkeck commented Jul 30, 2014 Related issue: #509. Sign up for free to join this conversation on GitHub.

This is the reason that hash(o1, o2) has to return a value different from 0. Cannot Be Cast To Java.lang.comparable Java I've read I need a Comparator or to implement Comparable but I don't know how to do that, and I think there might be a simpler solution (although perhaps not as new TreeMap(new Comparator() { public int compare(MyVertex o1, MyVertex o2) { //comparison logic goes here } }); Why is this necessary? get redirected here Should I report it?

public class MyVertex implements Comparable { @Override public int compareTo(Object o) { // comparison logic goes here } } or alternately, you can pass a comparator to the constructor of TreeMap. Java Treemap Comparator Example 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. Already have an account? If we got to the hashCode branch of our if-statement we already know that the objects are not equal.

Cannot Be Cast To Java.lang.comparable Java

more hot questions lang-java about us tour help blog chat data legal privacy policy work here advertising info mobile contact us feedback Technology Life / Arts Culture / Recreation Science Other Example for a commutative subring of a non-commutative ring Why do languages require parenthesis around expressions when used with "if" and "while"? Cannot Be Cast To Java.lang.comparable Treeset 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 Treeset Comparable Example asked 3 years ago viewed 9939 times active 4 months ago Upcoming Events 2016 Community Moderator Election ends Nov 22 Get the weekly newsletter!

TreeSetX.add("1"); TreeSetX.add("2"); TreeSetX.add("3"); Addind string object will give compareTo an idea onto how the sorting should be done. navigate to this website posted 7 years ago You can compare on two fields; first on one, and if that would lead to equality the other as well. You can add only one element into TreeSet which does not implement Comparable because it does not need to be compared with other elements. Hot Network Questions C++ calculator using classes Show that the square matrix A is invertible Ubuntu 16.04 installer cant see SSD drive GO OUT AND VOTE Formula 1 rebus Mimsy were Treemap Comparable Example

more stack exchange communities company blog Stack Exchange Inbox Reputation and Badges sign up log in tour help Tour Start here for a quick overview of the site Help Center Detailed extends T1, ? We will not break anything. More about the author Join them; it only takes a minute: Sign up Why does TreeSet throws ClassCastException up vote 6 down vote favorite 2 In below code I am trying to add two employee

extends U> operation); Also these have to be revised: @Override Tuple2.

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more stack exchange communities company blog Stack Exchange Inbox Reputation and Badges sign up log in tour help Tour Start here for a quick overview of the site Help Center Detailed Regarding thread-safety I also see no problem. Empty collections never call the comparator. Java Implement Comparable Your class does not.

Making the generic element / key type bound on Comparable was also not an option because then it wouldn't be possible to create a TreeSet / TreeMap with non-Comparable objects using Having no order will result in chaos. super E> comparator) { return new TreeSet(comparator); } public static click site It is important to provide a safe API, i.e.

With Comparable Not possible, you can sort the objects in the (only) way defined in compareTo() method. Rob Spoor Sheriff Posts: 20720 68 I like... super U, ? This would be a breaking change :-/ The other idea was to keep the API and internally use an `unordered comparator' instead (if that is possible).

With a custom Comparator you can still do it, but it's going to be harder. Agreed. I am using the Java JungI graph package and Netbeans 7. JΛVΛSLΛNG member ruslansennov commented Mar 24, 2016 Do you think this could work?

super K>) key; ... share|improve this answer edited Jun 22 at 7:19 answered Jan 3 '13 at 5:39 rahulroc 7,89121737 Comparable is generic –user102008 Jan 7 '13 at 22:02 add a comment| up I've learned that backward compatibility is the most important feature a library has. share|improve this answer edited Jan 2 '12 at 9:44 answered Jan 2 '12 at 9:32 plus- 20.1k104166 add a comment| Your Answer draft saved draft discarded Sign up or log

One available option is to change the signature of SortedSet flatMap(Function) in SortedSet to be Set flatMap(Function) and add a method SortedSet flatMapSorted(Function). Should you change a thermostat when changing your water pump Someone peeled an American flag sticker off of my truck. Comparators are shared between different persistent versions of a collection.