equals

Is there a standard technique to "extend" a class with private constructors, as with most Singleton classes? Specifcally, I'm trying to extend the java.lang.management.ThreadInfo class because I'm adding a LOT of them to a HashSet to control uniqueness. However, the way I determine if two threads are equal is different and not identical to the default implementation of the equals() method. Extending the class is obviously not an option in this case. Would it be reasonable to make something like a wrapper class which accepts a ThreadInfo in the constructor and then manually populates all

var a = new double[] {1, 2, 3}; var b = new double[] {1, 2, 3}; System.Console.WriteLine(Equals(a, b)); // Returns false However, I'm looking for a way to compare arrays which would compare the internal values instead of refernces. Is there a built in way to do this in .NET? Also, while I understand Equals comparing references, GetHashCode returns different values for these two arrays also, which I feel shouldn't happen, since they have the same internal values. I believe you are looking for the Enumerable.SequenceEqual<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) method. var a = new

If I have two std::function s, how can I check whether both hold the same function or not? Additional Information: I have a vector of functions std::vector<std::function<void()>> and before adding another function to the vector I want to check if it already is contained. I dont think that they both can be compared. Here is an example to explain some points on std::function comparison Generally std::function and boost::function are not comparable because they need their stored object be comparable but not all function objects and also lambdas have operator== so std or boost functions have no

Ive got one question. What happens when I try to add the "same" object twice to an ArrayList. With "the same" I mean an object of an individual class, which is identified as the same with equals() and hashCode(). It has different values for most of the member variables and was created from maybe different threads, but for equals() and hashCode() its the "same". Does the second object then replace the first object? Also, what happens if two threads try to add those objects exactly at the same time to the ArrayList? Is this even possible? If yes, what happens? Thank you! :-) [EDIT] Thanks for

I have the following class which contains only one field i . Access to this field is guarded by the lock of the object ("this"). When implementing equals() I need to lock this instance (a) and the other (b). If thread 1 calls a.equals(b) and at the same time thread 2 calls b.equals(a), the locking order is reverse in the two implementations and may result in deadlock. How should I implement equals() for a class which has synchronized fields? public class Sync { // @GuardedBy("this") private int i = 0; public synchronized int getI() {return i;} public synchronized void setI(int i) {this.i = i;}

After reading this question Why do "int" and "sbyte" GetHashCode functions generate different values? I wanted to dig further and found following behavior: sbyte i = 1; int j = 1; object.Equals(i, j) //false (1) object.Equals(j, i) //false (2) i.Equals(j) //false (3) j.Equals(i) //true (4) i == j //true (5) j == i //true (6) i.GetHashCode() == j.GetHashCode() //false (7) Difference between (3) and (4) breaks the requirement that Equals should be symmetric. Difference between (2) and (4) is not coherent with MSDN specification that says: If the two objects do not represent the same object

Folks, here's a thorny problem for you! A part of the TickZoom system must collect instances of every type of object into a Dictionary<> type. It is imperative that their equality and hash code be based on the instance of the object which means reference equality instead of value equality. The challenge is that some of the objects in the system have overridden Equals() and GetHashCode() for use as value equality and their internal values will change over time. That means that their Equals and GetHashCode are useless. How to solve this generically rather than intrusively? So far, We created a