1/*
2 * Copyright (C) 2009 Google Inc.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.google.common.collect;
18
19/**
20 * Thrown when a computer function returns null. This subclass exists so
21 * that our ReferenceCache adapter can differentiate null output from null
22 * keys, but we don't want to make this public otherwise.
23 *
24 * @author Bob Lee
25 */
26class NullOutputException extends NullPointerException {
27  public NullOutputException(String s) {
28    super(s);
29  }
30  private static final long serialVersionUID = 0;
31}
32