hashset

I am trying to implement a ConcurrentHashSet in the spirit of ConcurrentDictionary, approach taken is to use a internal backing ConcurrentDictionary and write small delegating methods, this is how far i got, but well the set theoretic methods are I am stuck on, esp. I am not sure if I can use a foreach and still not violate concurrency public class ConcurrentHashSet<TElement> : ISet<TElement> { private readonly ConcurrentDictionary<TElement, object> _internal; public ConcurrentHashSet(IEnumerable<TElement> elements = null) { _internal = new ConcurrentDictionary<TElement, object>(); if

I'm trying to use HashSet to store objects of a class that I created, but apparently the same objects seem to have two different hashes, which is why the contains method does not realize that the object is already in the HashSet. This leads to my program running out of heap memory. I don't think I'm doing anything wrong, but I wanted a second opinion anyway. I've done similar operations before which all worked fine, which makes this particularly annoying. I'd appreciate any help. Here's my code move1 = new Move(t,s); if(move1.hashCode()==new Move(t,s).hashCode()) System.out.println("match");

I've read this question about why it is not possible, but haven't found a solution to the problem. I would like to retrieve an item from a .NET HashSet<T> . I'm looking for a method that would have this signature: /// <summary> /// Determines if this set contains an item equal to <paramref name="item"/>, /// according to the comparison mechanism that was used when the set was created. /// The set is not changed. If the set does contain an item equal to /// <paramref name="item"/>, then the item from the set is returned. /// </summary> bool TryGetItem<T>(T item, out T foundItem); Searching the

Please consider the below piece of code: HashSet hs = new HashSet(); hs.add("hi"); -- (1) hs.add("hi"); -- (2) hs.size() will give 1 as HashSet doesn't allow duplicates so only one element will be stored. I want to know if we add the duplicate element, then does it replace the previous element or it simply doesn't add it? Also, what will happen using HashMap for the same case? In the case of HashMap , it replaces the old value with the new one. In the case of HashSet , the item isn't inserted. Jimmy The first thing you need to know is that HashSet acts like a Set , which means you add your

How can I iterate over a Set / HashSet without the following? Iterator iter = set.iterator(); while (iter.hasNext()) { System.out.println(iter.next()); } assylias You can use an enhanced for loop : Set<String> set = new HashSet<String>(); //populate set for (String s : set) { System.out.println(s); } Or with Java 8: set.forEach(System.out::println); There are at least six additional ways to iterate over a set. The following are known to me: Method 1 // Obsolete Collection Enumeration e = new Vector(movies).elements(); while (e.hasMoreElements()) { System.out.println(e.nextElement()); } Method