hashset

I am using the HashSet and Dictionary in C# to implement a Graph structure. I have a problem with the uniqueness of HashSet elements when the HashSet key is a customized class. Here I have: public class Point { public int x { get; set; } public int y { get; set; } } public class Vertex { public Vertex(Point point) { VertexLabel = point; } public Point VertexLabel { get; private set; } } public class Edge { public Edge(Vertex to, Vertex from, double weight) { FromVertex = from; ToVertex = to; Weight = weight; } public Vertex FromVertex { get; private set; } public Vertex ToVertex { get; private

Is there a HashSet in Delphi? I know using set can at most hold 255 items. Is there a HashSet in latest Delphi Compiler e.g. XE8, Seattle The standard collections do not offer a generic set class. Third party collections libraries such as Spring4D do. You can build a generic set class quite easily on top of TDictionary<K, V> . A bare bones version might look like this: type TSet<T> = class private FDict: TDictionary<T, Integer>; public constructor Create; destructor Destroy; override; function Contains(const Value: T): Boolean; procedure Include(const Value: T); procedure Exclude(const Value:

I am trying to determine to see if all elements in a list are same. such as: (10,10,10,10,10) --> true (10,10,20,30,30) --> false I know hashset might be helpful, but i don't know how to write in java. this is the one I've tried, but didn't work: public static boolean allElementsTheSame(List<String> templist) { boolean flag = true; String first = templist.get(0); for (int i = 1; i< templist.size() && flag; i++) { if(templist.get(i) != first) flag = false; } return true; } Using the Stream API (Java 8+) boolean allEqual = list.stream().distinct().limit(2).count() <= 1 or boolean allEqual = list

I've read this question: Changing the elements in a set changes the 'equals' semantics However, I don't know how to solve the problem that I can't change an item in the HashSet and remove it later. I have some example sourcecode: public static void main(String[] args) { TestClass testElement = new TestClass("1"); Set<TestClass> set = new HashSet<>(); set.add(testElement); printIt(testElement, set, "First Set"); testElement.setS1("asdf"); printIt(testElement, set, "Set after changing value"); set.remove(testElement); printIt(testElement, set, "Set after trying to remove value"); testElement

I have a list of a few thousand integer keys. The only thing I need to do with this list is say whether or not a given value is in the list. For C# I would use a HashSet to make that look-up fast. What's the JavaScript equivalent? Minimal support level: IE 9+, jQuery (current) Under the hood, the JavaScript Object is implemented with a hash table. So, your Key:Value pair would be (your integer):true A constant-time lookup function could be implemented as: var hash = { 1:true, 2:true, 7:true //etc... }; var checkValue = function(value){ return hash[value] === true; }; checkValue(7); // => true

I have the following code where I am trying to put the StringBuffer objects as keys in a TreeSet. The reason I do this is to see if I can put mutable objects as keys. I do not get any compile error. but when I run this code, I get the error that is below the code. specially, I get this java.lang.StringBuffer cannot be cast to java.lang.Comparable . what does this error indicate? from javadoc I see that StringBuffer class is declared final ( public final class StringBuffer ), doesn't that mean it is immutable and hence hashable? I am a newbie to the hashing and immutable stuff, so kindly help