001/*
002 * Copyright 2015-2017 UnboundID Corp.
003 * All Rights Reserved.
004 */
005/*
006 * Copyright (C) 2015-2017 UnboundID Corp.
007 *
008 * This program is free software; you can redistribute it and/or modify
009 * it under the terms of the GNU General Public License (GPLv2 only)
010 * or the terms of the GNU Lesser General Public License (LGPLv2.1 only)
011 * as published by the Free Software Foundation.
012 *
013 * This program is distributed in the hope that it will be useful,
014 * but WITHOUT ANY WARRANTY; without even the implied warranty of
015 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
016 * GNU General Public License for more details.
017 *
018 * You should have received a copy of the GNU General Public License
019 * along with this program; if not, see <http://www.gnu.org/licenses>.
020 */
021package com.unboundid.util.json;
022
023
024
025import com.unboundid.util.NotMutable;
026import com.unboundid.util.ThreadSafety;
027import com.unboundid.util.ThreadSafetyLevel;
028
029
030
031/**
032 * This class provides an implementation of a JSON value that represents a null
033 * value.  The string representation of the null value is {@code null} in all
034 * lowercase and without any quotation marks.
035 */
036@NotMutable()
037@ThreadSafety(level=ThreadSafetyLevel.COMPLETELY_THREADSAFE)
038public final class JSONNull
039       extends JSONValue
040{
041  /**
042   * A pre-allocated JSON null value object.
043   */
044  public static final JSONNull NULL = new JSONNull();
045
046
047
048  /**
049   * The serial version UID for this serializable class.
050   */
051  private static final long serialVersionUID = -8359265286375144526L;
052
053
054
055  /**
056   * Creates a new JSON value capable of representing a {@code null} value.
057   */
058  public JSONNull()
059  {
060  }
061
062
063
064  /**
065   * {@inheritDoc}
066   */
067  @Override()
068  public int hashCode()
069  {
070    return 1;
071  }
072
073
074
075  /**
076   * {@inheritDoc}
077   */
078  @Override()
079  public boolean equals(final Object o)
080  {
081    return ((o == this) || (o instanceof JSONNull));
082  }
083
084
085
086  /**
087   * {@inheritDoc}
088   */
089  @Override()
090  public boolean equals(final JSONValue v, final boolean ignoreFieldNameCase,
091                        final boolean ignoreValueCase,
092                        final boolean ignoreArrayOrder)
093  {
094    return (v instanceof JSONNull);
095  }
096
097
098
099  /**
100   * Retrieves a string representation of this null value as it should appear
101   * in a JSON object.  Null values will always have a string representation of
102   * "{@code null}" (without the surrounding quotes).
103   *
104   * @return  A string representation of this null value as it should appear
105   *          in a JSON object.
106   */
107  @Override()
108  public String toString()
109  {
110    return "null";
111  }
112
113
114
115  /**
116   * Appends a string representation of this null value as it should appear
117   * in a JSON object to the provided buffer.  Null values will always have a
118   * string representation of "{@code null}" (without the surrounding quotes).
119   *
120   * @param  buffer  The buffer to which the information should be appended.
121   */
122  @Override()
123  public void toString(final StringBuilder buffer)
124  {
125    buffer.append("null");
126  }
127
128
129
130  /**
131   * Retrieves a single-line string representation of this null value as it
132   * should appear in a JSON object.  Null values will always have a string
133   * representation of "{@code null}" (without the surrounding quotes).
134   *
135   * @return  A single-line string representation of this null value as it
136   *          should appear in a JSON object.
137   */
138  @Override()
139  public String toSingleLineString()
140  {
141    return "null";
142  }
143
144
145
146  /**
147   * Appends a single-line string representation of this null value as it should
148   * appear in a JSON object to the provided buffer.  Null values will always
149   * have a string representation of "{@code null}" (without the surrounding
150   * quotes).
151   *
152   * @param  buffer  The buffer to which the information should be appended.
153   */
154  @Override()
155  public void toSingleLineString(final StringBuilder buffer)
156  {
157    buffer.append("null");
158  }
159
160
161
162  /**
163   * Retrieves a normalized string representation of this null value as it
164   * should appear in a JSON object.  Null values will always have a string
165   * representation of "{@code null}" (without the surrounding quotes).
166   *
167   * @return  A normalized string representation of this null value as it
168   *          should appear in a JSON object.
169   */
170  @Override()
171  public String toNormalizedString()
172  {
173    return "null";
174  }
175
176
177
178  /**
179   * Appends a normalized string representation of this null value as it should
180   * appear in a JSON object to the provided buffer.  Null values will always
181   * have a string representation of "{@code null}" (without the surrounding
182   * quotes).
183   *
184   * @param  buffer  The buffer to which the information should be appended.
185   */
186  @Override()
187  public void toNormalizedString(final StringBuilder buffer)
188  {
189    buffer.append("null");
190  }
191
192
193
194  /**
195   * {@inheritDoc}
196   */
197  @Override()
198  public void appendToJSONBuffer(final JSONBuffer buffer)
199  {
200    buffer.appendNull();
201  }
202
203
204
205  /**
206   * {@inheritDoc}
207   */
208  @Override()
209  public void appendToJSONBuffer(final String fieldName,
210                                 final JSONBuffer buffer)
211  {
212    buffer.appendNull(fieldName);
213  }
214}