code: // from gee.cs.oswego.edu/home/jsr166/jsr166
  
  package jsr166tests.jtreg.util.Map;
  
  /*
   * Copyright 2005 Sun Microsystems, Inc.  All Rights Reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.
   *
   * This code 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
   * version 2 for more details (a copy is included in the LICENSE file that
   * accompanied this code).
   *
   * You should have received a copy of the GNU General Public License version
   * 2 along with this work; if not, write to the Free Software Foundation,
   * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
   * CA 95054 USA or visit www.sun.com if you need additional information or
   * have any questions.
   */
  
  /*
   * @test
   * @bug 6306829
   * @summary Verify assertions in get() javadocs
   * @author Martin Buchholz
   */
  
  import edu.stanford.ppl.concurrent.SnapTreeMap;
  
  import java.io.*;
  import java.util.*;
  import java.util.concurrent.*;
  import java.util.concurrent.atomic.*;
  
  public class Get {
  
      private static void realMain(String[] args) throws Throwable {
          testMap(new Hashtable<Character,Boolean>());
          testMap(new HashMap<Character,Boolean>());
          testMap(new IdentityHashMap<Character,Boolean>());
          testMap(new LinkedHashMap<Character,Boolean>());
          testMap(new ConcurrentHashMap<Character,Boolean>());
          testMap(new WeakHashMap<Character,Boolean>());
          testMap(new TreeMap<Character,Boolean>());
          testMap(new ConcurrentSkipListMap<Character,Boolean>());
          testMap(new SnapTreeMap<Character,Boolean>());
      }
  
      private static void put(Map<Character,Boolean> m,
                              Character key, Boolean value,
                              Boolean oldValue) {
          if (oldValue != null) {
              check(m.containsValue(oldValue));
              check(m.values().contains(oldValue));
          }
          equal(m.put(key, value), oldValue);
          equal(m.get(key), value);
          check(m.containsKey(key));
          check(m.keySet().contains(key));
          check(m.containsValue(value));
          check(m.values().contains(value));
          check(! m.isEmpty());
      }
  
      private static void testMap(Map<Character,Boolean> m) {
          // We verify following assertions in get(Object) method javadocs
          boolean permitsNullKeys = (! (m instanceof ConcurrentMap ||
                                        m instanceof Hashtable     ||
                                        m instanceof SortedMap));
          boolean permitsNullValues = (! (m instanceof ConcurrentMap ||
                                          m instanceof Hashtable));
          boolean usesIdentity = m instanceof IdentityHashMap;
  
          System.out.println(m.getClass());
          put(m, 'A', true,  null);
          put(m, 'A', false, true);       // Guaranteed identical by JLS
          put(m, 'B', true,  null);
          put(m, new Character('A'), false, usesIdentity ? null : false);
          if (permitsNullKeys) {
              try {
                  put(m, null, true,  null);
                  put(m, null, false, true);
              }
              catch (Throwable t) { unexpected(t); }
          } else {
              try { m.get(null); fail(); }
              catch (NullPointerException e) {}
              catch (Throwable t) { unexpected(t); }
  
              try { m.put(null, true); fail(); }
              catch (NullPointerException e) {}
              catch (Throwable t) { unexpected(t); }
          }
          if (permitsNullValues) {
              try {
                  put(m, 'C', null, null);
                  put(m, 'C', true, null);
                  put(m, 'C', null, true);
              }
              catch (Throwable t) { unexpected(t); }
          } else {
              try { m.put('A', null); fail(); }
              catch (NullPointerException e) {}
              catch (Throwable t) { unexpected(t); }
  
              try { m.put('C', null); fail(); }
              catch (NullPointerException e) {}
              catch (Throwable t) { unexpected(t); }
          }
      }
  
      //--------------------- Infrastructure ---------------------------
      static volatile int passed = 0, failed = 0;
      static void pass() { passed++; }
      static void fail() { failed++; Thread.dumpStack(); }
      static void fail(String msg) { System.out.println(msg); fail(); }
      static void unexpected(Throwable t) { failed++; t.printStackTrace(); }
      static void check(boolean cond) { if (cond) pass(); else fail(); }
      static void equal(Object x, Object y) {
          if (x == null ? y == null : x.equals(y)) pass();
          else {System.out.println(x + " not equal to " + y); fail(); }}
  
      public static void main(String[] args) throws Throwable {
          try { realMain(args); } catch (Throwable t) { unexpected(t); }
  
          System.out.printf("%nPassed = %d, failed = %d%n%n", passed, failed);
          if (failed > 0) throw new Exception("Some tests failed");
      }
  }
  