01: /*
02: * Copyright 2007 Google Inc.
03: *
04: * Licensed under the Apache License, Version 2.0 (the "License"); you may not
05: * use this file except in compliance with the License. You may obtain a copy of
06: * the License at
07: *
08: * http://www.apache.org/licenses/LICENSE-2.0
09: *
10: * Unless required by applicable law or agreed to in writing, software
11: * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12: * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13: * License for the specific language governing permissions and limitations under
14: * the License.
15: */
16: package com.google.gwt.json.client;
17:
18: /**
19: * Represents the JSON <code>null</code> value.
20: */
21: public class JSONNull extends JSONValue {
22:
23: private static final JSONNull instance = new JSONNull();
24:
25: /**
26: * Returns the singleton null-valued JSON object.
27: */
28: public static JSONNull getInstance() {
29: return instance;
30: }
31:
32: /**
33: * There should only be one null value.
34: */
35: private JSONNull() {
36: }
37:
38: /**
39: * Returns <code>this</code>, as this is a JSONNull.
40: */
41: @Override
42: public JSONNull isNull() {
43: return this ;
44: }
45:
46: /**
47: * Returns "null" to allow for formatting <code>null</code> values.
48: */
49: @Override
50: public String toString() {
51: return "null";
52: }
53:
54: }
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