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
Since you didn’t override equals in your class, assertEquals behaves the same as assertSame since the default equals implementation compare references. 150 public boolean equals(Object obj) { 151 return (this == obj); 152 } If you provide a dumb overriding of equals: class SomeClass { @Override public boolean equals(Object o) { return true; } } … Read more
Just because your Test‘s equals may return true when you pass a String to it doesn’t mean that String‘s equals will ever return true when you pass a Test instance to it. In fact, String‘s equals can only return true when the instance passed to it is another String : public boolean equals(Object anObject) { … Read more
Check out this article: Boxed values and equality When comparing wrapper types such as Integers, Longs or Booleans using == or !=, you’re comparing them as references, not as values. If two variables point at different objects, they will not == each other, even if the objects represent the same value. Example: Comparing different Integer … 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
This doesn’t have unsafe blocks and won’t display the password in plaintext: public static bool IsEqualTo(this SecureString ss1, SecureString ss2) { IntPtr bstr1 = IntPtr.Zero; IntPtr bstr2 = IntPtr.Zero; try { bstr1 = Marshal.SecureStringToBSTR(ss1); bstr2 = Marshal.SecureStringToBSTR(ss2); int length1 = Marshal.ReadInt32(bstr1, -4); int length2 = Marshal.ReadInt32(bstr2, -4); if (length1 == length2) { for (int x … Read more
There’s a nice explanation by Matt Warren at The Moth: “The reason C# has the word ‘equals’ instead of the ‘==’ operator was to make it clear that the ‘on’ clause needs you to supply two separate expressions that are compared for equality not a single predicate expression. The from-join pattern maps to the Enumerable.Join() … Read more
If you have these arrays in something inheriting from Collection, you can just use collection.containsAll( otherCollection ) from the Collection interface. However, you’ll also need to compare the lengths of the two to verify that one set isn’t a superset of the other. (Thanks go to Aardvarkk and piegames.) http://docs.oracle.com/javase/6/docs/api/java/util/Collection.html#containsAll(java.util.Collection) Note: This will work up … Read more
You can’t change the type of hashCode, nor should you want to. I’d just go with something like: public int hashCode() { return x * 31 + y; } Note that this means that (a, b) is different to (b, a) for most cases (unlike e.g. adding or XOR-ing). This can be useful if you … Read more