If you are fortunate enough to be using JDK 7, the newly available Objects class is the obvious (at least to me) choice for implementing the “common” Java object ...

which rely on the hashCode and equals methods to determine object uniqueness, membership, and ordering. "identical" and "identity" aren't the same thing. Two string that contain the same content ...

Great! But now you have to implement hashCode as well. Let’s see why and how to do it correctly. The variable contains is true because, while instances of "b" are not identical (again, ignoring String ...

Java’s equals() and hashcode() are two methods that work together to verify if two objects have the same value. You can use them to make object comparisons easy and efficient in your Java programs.

java.lang.NullPointerException: Attempt to invoke virtual method 'int java.lang.String.hashCode()' on a null object reference at pl.mytest.app.data.point.dto ...