It works for you because your code does not use any functionality (HashMap, HashTable) which needs the hashCode() API. However, you don’t know whether your class (presumably not written as a one-off) will be later called in a code that does indeed use its objects as hash key, in which case things will be affected. … Read more
I agree with the comment of I82Much that you should avoid having B referencing their parent: it’s information duplication, which usually only leads to trouble, but you might need to do so in your case. Even if you leave the parent reference in B, as far as hash codes are concerned you should completely ignore … Read more
Yes the probability of hashcode collision is very low as for example in case of String it depends upon the string value. If we are not creating any String with new operator then if the a new String has the same value that already present , then new String object is not created, it refers … Read more
The hash code for conforming List implementations has been specified in the interface: Returns the hash code value for this list. The hash code of a list is defined to be the result of the following calculation: int hashCode = 1; for (E e : list) hashCode = 31*hashCode + (e==null ? 0 : e.hashCode()); … Read more
I just hashed 58 thousand English language words (found here), both all-lowercase and also with the first letter capitalized . Know how many collided? Two: “Siblings” and “Teheran” (an alternate spelling of “Tehran”). Just like you, I took a subdomain (in my case a likely one) of possible strings and analyzed the hashCode collision rate … Read more
For the hashCode of an int the most natural choice is to use the int itself. A better question is what to use for the hashCode of a long since it doesn’t fit into the int-sized hashcode. Generally, your best source for that—and all hashCode-related questions—would be Effective Java. Here’s what Effective Java recommends (and … Read more
.NET’s implementation is intentionally not published (and when you attempt to decompile it, you will find that it makes an unmanaged framework call). The only documentation as such is here, which only states that it is “not guaranteed to produce a different value for each object”, and “may change between framework versions”. Making any assumptions … Read more
Why do hash codes for string change for every execution in .NET In short to prevent hash collision attacks. You can roughly find out the reason from the docs of the <UseRandomizedStringHashAlgorithm> configuration element: The string lookup in a hash table is typically an O(1) operation. However, when a large number of collisions occur, the … Read more
HashMap does not call hashcode when null is passed as key and null Key is handled as special case. Put Method HashMap puts null key in bucket 0 and maps null as key to passed value. HashMap does it by linked list data structure. HashMap uses linked list data structure internally. Linked list data structure … Read more
hashCode and equals generation using the Java 7 Objects class has now been implemented in Eclipse. I was working on the feature request 424214 back in August 2018 and my contributions were merged in the JDT UI codebase shortly afterwards (see commit f543cd6). Here’s an overview of the new option in the Source > Generate … Read more