if (comparator != null) {
      return comparator;
    }
    throw new UnsupportedOperationException("This ordering does not define a comparator.");
  }

  @Override
  public boolean equals(@CheckForNull Object obj) {
    if (obj == this) {
      return true;
    }
    if (!(obj instanceof ElementOrder)) {
      return false;
    }

    ElementOrder<?> other = (ElementOrder<?>) obj;

    if (comparator != null) {
      return comparator;
    }
    throw new UnsupportedOperationException("This ordering does not define a comparator.");
  }

  @Override
  public boolean equals(@CheckForNull Object obj) {
    if (obj == this) {
      return true;
    }
    if (!(obj instanceof ElementOrder)) {
      return false;
    }

    ElementOrder<?> other = (ElementOrder<?>) obj;

 * high contention, expected throughput of this class is significantly higher, at the expense of
 * higher space consumption.
 *
 * <p>This class extends {@link Number}, but does not define methods such as {@code
 * equals}, {@code hashCode} and {@code compareTo} because instances are expected to be mutated, and
 * so are not useful as collection keys.
 *
 * <p>jsr166e note: This class is targeted to be placed in java.util.concurrent.atomic.

     */
    public static boolean getBoolean ( Properties props, String key, boolean def ) {
        String b = props.getProperty(key);
        if ( b != null ) {
            def = b.toLowerCase().equals("true");
        }
        return def;
    }


    /**
     * Retrieve an array of <tt>InetAddress</tt> created from a property
     * value containing a <tt>delim</tt> separated list of host names and/or

     * @param target1
     *            文字列1
     * @param target2
     *            文字列2
     * @return 文字列同士が等しいかどうか
     */
    public static boolean equals(final String target1, final String target2) {
        return target1 == null ? target2 == null : target1.equals(target2);
    }

    /**
     * 大文字小文字を無視して文字列同士が等しいかどうか返します。どちらもnullの場合は、<code>true</code>を返します。
     *
     * @param target1
     *            文字列1

   * returns {@code null}, returns a map containing null keys or values, or fails to return an entry
   * for each requested key.
   *
   * <p>Note that duplicate elements in {@code keys}, as determined by {@link Object#equals}, will
   * be ignored.
   *
   * @throws ExecutionException if a checked exception was thrown while loading the value. ({@code
   *     ExecutionException} is thrown <a

              K key = entry.getKey();
              Collection<V> collection =
                  filterCollection(entry.getValue(), new ValuePredicate(key));
              if (!collection.isEmpty() && c.equals(collection)) {
                if (collection.size() == entry.getValue().size()) {
                  entryIterator.remove();
                } else {
                  collection.clear();
                }

 * {@link #compareAndSet} by comparing their bitwise representation using {@link
 * Double#doubleToRawLongBits}, which differs from both the primitive double {@code ==} operator and
 * from {@link Double#equals}, as if implemented by:
 *
 * <pre>{@code
 * static boolean bitEquals(double x, double y) {
 *   long xBits = Double.doubleToRawLongBits(x);
 *   long yBits = Double.doubleToRawLongBits(y);
 *   return xBits == yBits;

     */

    public static boolean getBoolean( String key, boolean def ) {
        String b = getProperty( key );
        if( b != null ) {
            def = b.toLowerCase().equals( "true" );
        }
        return def;
    }

    /**
     * Retrieve an array of <tt>InetAddress</tt> created from a property
     * value containting a <tt>delim</tt> separated list of hostnames and/or

      cache.invalidateAll();
      checkEmpty(cache);
    }
  }


  public void testEquals_null() {
    for (LoadingCache<Object, Object> cache : caches()) {
      assertFalse(cache.equals(null));
    }
  }

  public void testEqualsAndHashCode_different() {
    for (CacheBuilder<Object, Object> builder : cacheFactory().buildAllPermutations()) {
      // all caches should be different: instance equality