Question

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what is an objects hashcode

When i run this sample program

public class ZiggyTest {
    public static void main (String[] args){
        Object now = new Object();
        System.out.println(now);
    }
}

The output is

java.lang.Object@3e25a5

I understand that the number 3e25a5 is the hashcode value that represents the object. Where and how is this calculated/derived?

Answer 1

According to the documentation:

As much as is reasonably practical, the hashCode method defined by
class Object does return distinct integers for distinct objects. (This
is typically implemented by converting the internal address of the
object into an integer, but this implementation technique is not
required by the Java programming language.)

Note that accordingly, the exact formula is not defined by Java and can vary by JVM implementation and JVM version.