package container;

/** Used to compare keys for equality, just as java.util.Comparator
 * compares them for order.  A hash function should also be defined
 * so that equal keys get the same hash code.
 *
 * An EqualityTester object might expect keys of a particular type.
 * Then its methods should throw a ClassCastException when given keys
 * of the wrong type.
 */

public interface EqualityTester {

  public boolean equal(Object a, Object b) throws ClassCastException;

  public int hash(Object a) throws ClassCastException;
}



   // Note that these methods are NOT called equals() and hashCode().
   // That's because an EqualityTester already has methods by those
   // names, inherited from Object.  For instance, equals() tests whether
   // two EqualityTesters are equal -- which is not what we want!