If you’ve ever done a toString on an object that doesn’t override toString(), you’ve probably noticed that it returns something like this.

com.mycode.MyClass@1312311

Now the big question: can two different object instances ever have the same value after the ‘at’ (@) sign?

The answer is yes. If you look at the source for Java’s Object class, the toString() method prints the name of the class, the @, and the value of the hashCode() method. If your class overrides hashCode(), and you create two objects that have the same exact hash code (because all of their values are identical), then you can reproduce this behavior.

I’ve always naively assumed that the number after the @ was always the object’s memory address in the heap.