// equalshashcode/Groundhog2.java

// (c)2021 MindView LLC: see Copyright.txt

// We make no guarantees that this code is fit for any purpose.

// Visit http://OnJava8.com for more book information.

// A class that's used as a key in a HashMap

// must override hashCode() and equals()

import java.util.*;

public class Groundhog2 extends Groundhog {

public Groundhog2(int n) { super(n); }

@Override

public int hashCode() { return number; }

@Override public boolean equals(Object o) {

return o instanceof Groundhog2 &&

Objects.equals(

number, ((Groundhog2)o).number);

}

}