OnJava8-Examples/equalshashcode/Equality.java

// equalshashcode/Equality.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.
import java.util.*;

public class Equality {
  protected int i;
  protected String s;
  protected double d;
  public Equality(int i, String s, double d) {
    this.i = i;
    this.s = s;
    this.d = d;
    System.out.println("made 'Equality'");
  }
  @Override public boolean equals(Object rval) {
    if(rval == null)
      return false;
    if(rval == this)
      return true;
    if(!(rval instanceof Equality))
      return false;
    Equality other = (Equality)rval;
    if(!Objects.equals(i, other.i))
      return false;
    if(!Objects.equals(s, other.s))
      return false;
    if(!Objects.equals(d, other.d))
      return false;
    return true;
  }
  public void
  test(String descr, String expected, Object rval) {
    System.out.format("-- Testing %s --%n" +
      "%s instanceof Equality: %s%n" +
      "Expected %s, got %s%n",
      descr, descr, rval instanceof Equality,
      expected, equals(rval));
  }
  public static void testAll(EqualityFactory eqf) {
    Equality
      e = eqf.make(1, "Monty", 3.14),
      eq = eqf.make(1, "Monty", 3.14),
      neq = eqf.make(99, "Bob", 1.618);
    e.test("null", "false", null);
    e.test("same object", "true", e);
    e.test("different type",
           "false", Integer.valueOf(99));
    e.test("same values", "true", eq);
    e.test("different values", "false", neq);
  }
  public static void main(String[] args) {
    testAll( (i, s, d) -> new Equality(i, s, d));
  }
}
/* Output:
made 'Equality'
made 'Equality'
made 'Equality'
-- Testing null --
null instanceof Equality: false
Expected false, got false
-- Testing same object --
same object instanceof Equality: true
Expected true, got true
-- Testing different type --
different type instanceof Equality: false
Expected false, got false
-- Testing same values --
same values instanceof Equality: true
Expected true, got true
-- Testing different values --
different values instanceof Equality: true
Expected false, got false
*/