Home > Cannot Be > Cannot Be Cast To Java.lang.comparable Treemap

Cannot Be Cast To Java.lang.comparable Treemap

Contents

Even better would be to take the naturalComparator, if there exsists an order and the unordered comparator as fallback. If you check TreeMap code you will see that if the comparator wasn't found within the Map object, it will try to cast the key (your Employee object) directly to Comparator: It wasn't accurate It wasn't clear It wasn't relevant Submit feedback Cancel Have a question about this article? See my answer. –NPE Apr 11 '13 at 7:38 add a comment| up vote 1 down vote TreeSet requires for elements to implement Comparable if a custom Comparator is not set. have a peek here

Why did the best potions master have greasy hair? Once the element type is determined and therefore the comparator's state is initialized, the comparator can be shared between difference versions of the collection (e,.g. I think we can make it safe but it would change the semantics of the current implementation. Why had Dumbledore accepted Lupin's resignation? http://stackoverflow.com/questions/14133600/java-cannot-cast-to-comparable-when-using-treemap

Cannot Be Cast To Java.lang.comparable Treeset

Actually, the latter would have given a compiler error since Java 5.0, but before it would have given the error. java sorting exception classcastexception comparable share|improve this question edited Oct 31 '13 at 21:38 Mostafa Jamareh 74811340 asked Oct 31 '13 at 21:18 user2234225 19113 1 How do you run Either implement it: public class Stock implements Comparable { public int compareTo(Stock o) { // ... } } ... current community chat Stack Overflow Meta Stack Overflow your communities Sign up or log in to customize your list.

Then it means that when you want to use a TreeSet for your Set implementation, then either you need to make all your code aware that it's a TreeSet so you To correct this issue, you should create a TreeMap by providing your own custom Comparator for comparing Set instances. Java is doing the same, e.g. Classcastexception Comparable The same applies to SortedSet.map.

are you sure the exception from above code? Cannot Be Cast To Java.lang.comparable Java How to use?0Cast TreeMap.Submap return: SortedMap, back to TreeMap13Find element position in a Java TreeMap14Java TreeMap Comparator4Java. The underlying RedBlackTree performs a binary search along the left/right tree branches. http://stackoverflow.com/questions/19716790/myclass-cannot-be-cast-to-java-lang-comparable-java-lang-classcastexception java.util.stream.Stream.sorted().

take(0) and then perend(elem) etc.). Cannot Be Cast To Java.lang.comparable Priority Queue I cannot reproduce the problem with Java collections because there is no default collector that creates a SortedSet: java.util.SortedSet sortedSet = new TreeSet<>(); sortedSet.add("a"); sortedSet.add("b"); sortedSet .stream() .flatMap(s -> Arrays.asList(s.hashCode()).stream()) .collect(Collectors.toSet()); Thanks Rob for the above . But this is not possible in the case of empty collections where we can't take an element to check if it is comparable.

Cannot Be Cast To Java.lang.comparable Java

Why is this C++ code faster than my hand-written assembly for testing the Collatz conjecture? Why is this necessary? (I do not immediately see the reason) java casting treemap comparable sortedmap share|improve this question edited Jan 3 '13 at 6:07 user166390 asked Jan 3 '13 at Cannot Be Cast To Java.lang.comparable Treeset Good programmers write code that humans can understand." --- Martin Fowler Please correct my English. Treemap Comparable Example You can add only one element into TreeSet which does not implement Comparable because it does not need to be compared with other elements.

What is the definition of "rare language"? navigate here Why was this unhelpful? Implement Comparable interface. Agreed. Treeset Comparable Example

It is no viable solution to search (once) for the most common comparator of two objects o1, o2. n-dimensional circles! public class ComparatorTest { @org.junit.Test public void compare() throws Exception { java.util.Comparator wonkyComparator = new Comparator(); // ints assertEquals(Integer.compare(5, 9), wonkyComparator.compare(5, 9)); // anon objects Object a = new Object(){ int Check This Out TreeSet and TreeMap use sorting for their internal storage.

up vote 0 down vote favorite So I'm trying to move all Strings of a certain length from a Collection of Strings (could either be a Set or a List) to Treeset With Comparator The added object cannot be compared with the elements currently in the set, the add(Object) call throws a ClassCastException. Please remove this question asap. –user2234225 Oct 31 '13 at 21:46 add a comment| Your Answer draft saved draft discarded Sign up or log in Sign up using Google Sign

Just found out there's a typo in the txt file making a null object created and added to the ArrayList.

Java's int is 32 bit, our machines address 64 bit memory. 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 Personal Open source Business Explore Sign up Sign in Pricing Blog Support Search GitHub This repository Watch 72 Star 1,274 Fork 151 javaslang/javaslang Code Issues 85 Pull requests 9 Projects Java Treemap Comparator Example Sign in to comment Contact GitHub API Training Shop Blog About © 2016 GitHub, Inc.

We should use an existing Comparator before testing for equality (which might be costly). more hot questions question feed 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 kag0 commented Oct 1, 2016 Doesn't the lazy comparator have the same issue ruslan pointed out? http://electrictricycle.net/cannot-be/cannot-be-cast-to-java-lang-comparable-set.html My manager said I spend too much time on Stack Exchange.

What is really curved, spacetime, or simply the coordinate lines? 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. super U, ? 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.

more hot questions question feed 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 Assigning a unique representation to equivalent circular queues more hot questions question feed lang-java about us tour help blog chat data legal privacy policy work here advertising info mobile contact us But for the case where just pass your custom Comparator, you don't need to make Stock to be a Comparable. Solutions?

Reload to refresh your session. I need to check if there are benefits when we make the instance variable volatile. The following code makes Employee elements comparable. import java.util.SortedSet; import java.util.TreeSet; public class Main { public static void main(String[] args) { SortedSet sse = One Very Odd Email Does sputtering butter mean that water is present?