identityHashCode.java

// Tags: JDK1.1

// Copyright (C) 2002 Free Software Foundation, Inc.
// Written by Mark Wielaard (mark@klomp.org)
//
// This file is part of Mauve.

// Mauve is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2, or (at your option)
// any later version.

// Mauve is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with Mauve; see the file COPYING.  If not, write to
// the Free Software Foundation, 59 Temple Place - Suite 330,
// Boston, MA 02111-1307, USA.  */

package gnu.testlet.wonka.lang.System;

import gnu.testlet.Testlet;
import gnu.testlet.TestHarness;

public class identityHashCode implements Testlet
{
  public int hashCode()
  {
    return 42;
  }

  private int origHashCode()
  {
    return super.hashCode();
  }

  public void test (TestHarness harness)
  {
    // Returns the same as hash code for any object that does not override it.
    Object o = new Object();
    harness.check(System.identityHashCode(o), o.hashCode());

    // Exception also does not override hashCode
    o = new Exception();
    harness.check(System.identityHashCode(o), o.hashCode());

    // When a class overrides it you can still get the original
    identityHashCode ihc = new identityHashCode();
    harness.check(System.identityHashCode(ihc), ihc.origHashCode());

    // null has identityHashCode zero
    harness.check(System.identityHashCode(null), 0);
  }
}