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| 1 | /* | ||
| 2 | * Copyright (c) 2003, 2007, Oracle and/or its affiliates. All rights reserved. | ||
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | ||
| 4 | * | ||
| 5 | * This code is free software; you can redistribute it and/or modify it | ||
| 6 | * under the terms of the GNU General Public License version 2 only, as | ||
| 7 | * published by the Free Software Foundation. Oracle designates this | ||
| 8 | * particular file as subject to the "Classpath" exception as provided | ||
| 9 | * by Oracle in the LICENSE file that accompanied this code. | ||
| 10 | * | ||
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT | ||
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | ||
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | ||
| 14 | * version 2 for more details (a copy is included in the LICENSE file that | ||
| 15 | * accompanied this code). | ||
| 16 | * | ||
| 17 | * You should have received a copy of the GNU General Public License version | ||
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, | ||
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | ||
| 20 | * | ||
| 21 | * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | ||
| 22 | * or visit www.oracle.com if you need additional information or have any | ||
| 23 | * questions. | ||
| 24 | */ | ||
| 25 | |||
| 26 | /* | ||
| 27 | * Portions Copyright IBM Corporation, 1997, 2001. All Rights Reserved. | ||
| 28 | */ | ||
| 29 | |||
| 30 | package java.math; | ||
| 31 | import java.io.*; | ||
| 32 | |||
| 33 | /** | ||
| 34 | * Immutable objects which encapsulate the context settings which | ||
| 35 | * describe certain rules for numerical operators, such as those | ||
| 36 | * implemented by the {@link BigDecimal} class. | ||
| 37 | * | ||
| 38 | * <p>The base-independent settings are: | ||
| 39 | * <ol> | ||
| 40 | * <li>{@code precision}: | ||
| 41 | * the number of digits to be used for an operation; results are | ||
| 42 | * rounded to this precision | ||
| 43 | * | ||
| 44 | * <li>{@code roundingMode}: | ||
| 45 | * a {@link RoundingMode} object which specifies the algorithm to be | ||
| 46 | * used for rounding. | ||
| 47 | * </ol> | ||
| 48 | * | ||
| 49 | * @see BigDecimal | ||
| 50 | * @see RoundingMode | ||
| 51 | * @author Mike Cowlishaw | ||
| 52 | * @author Joseph D. Darcy | ||
| 53 | * @since 1.5 | ||
| 54 | */ | ||
| 55 | |||
| 56 | public final class MathContext implements Serializable { | ||
| 57 | |||
| 58 | /* ----- Constants ----- */ | ||
| 59 | |||
| 60 | // defaults for constructors | ||
| 61 | private static final int DEFAULT_DIGITS = 9; | ||
| 62 | private static final RoundingMode DEFAULT_ROUNDINGMODE = RoundingMode.HALF_UP; | ||
| 63 | // Smallest values for digits (Maximum is Integer.MAX_VALUE) | ||
| 64 | private static final int MIN_DIGITS = 0; | ||
| 65 | |||
| 66 | // Serialization version | ||
| 67 | private static final long serialVersionUID = 5579720004786848255L; | ||
| 68 | |||
| 69 | /* ----- Public Properties ----- */ | ||
| 70 | /** | ||
| 71 | * A {@code MathContext} object whose settings have the values | ||
| 72 | * required for unlimited precision arithmetic. | ||
| 73 | * The values of the settings are: | ||
| 74 | * <code> | ||
| 75 | * precision=0 roundingMode=HALF_UP | ||
| 76 | * </code> | ||
| 77 | */ | ||
| 78 | public static final MathContext UNLIMITED = | ||
| 79 | new MathContext(0, RoundingMode.HALF_UP); | ||
| 80 | |||
| 81 | /** | ||
| 82 | * A {@code MathContext} object with a precision setting | ||
| 83 | * matching the IEEE 754R Decimal32 format, 7 digits, and a | ||
| 84 | * rounding mode of {@link RoundingMode#HALF_EVEN HALF_EVEN}, the | ||
| 85 | * IEEE 754R default. | ||
| 86 | */ | ||
| 87 | public static final MathContext DECIMAL32 = | ||
| 88 | new MathContext(7, RoundingMode.HALF_EVEN); | ||
| 89 | |||
| 90 | /** | ||
| 91 | * A {@code MathContext} object with a precision setting | ||
| 92 | * matching the IEEE 754R Decimal64 format, 16 digits, and a | ||
| 93 | * rounding mode of {@link RoundingMode#HALF_EVEN HALF_EVEN}, the | ||
| 94 | * IEEE 754R default. | ||
| 95 | */ | ||
| 96 | public static final MathContext DECIMAL64 = | ||
| 97 | new MathContext(16, RoundingMode.HALF_EVEN); | ||
| 98 | |||
| 99 | /** | ||
| 100 | * A {@code MathContext} object with a precision setting | ||
| 101 | * matching the IEEE 754R Decimal128 format, 34 digits, and a | ||
| 102 | * rounding mode of {@link RoundingMode#HALF_EVEN HALF_EVEN}, the | ||
| 103 | * IEEE 754R default. | ||
| 104 | */ | ||
| 105 | public static final MathContext DECIMAL128 = | ||
| 106 | new MathContext(34, RoundingMode.HALF_EVEN); | ||
| 107 | |||
| 108 | /* ----- Shared Properties ----- */ | ||
| 109 | /** | ||
| 110 | * The number of digits to be used for an operation. A value of 0 | ||
| 111 | * indicates that unlimited precision (as many digits as are | ||
| 112 | * required) will be used. Note that leading zeros (in the | ||
| 113 | * coefficient of a number) are never significant. | ||
| 114 | * | ||
| 115 | * <p>{@code precision} will always be non-negative. | ||
| 116 | * | ||
| 117 | * @serial | ||
| 118 | */ | ||
| 119 | final int precision; | ||
| 120 | |||
| 121 | /** | ||
| 122 | * The rounding algorithm to be used for an operation. | ||
| 123 | * | ||
| 124 | * @see RoundingMode | ||
| 125 | * @serial | ||
| 126 | */ | ||
| 127 | final RoundingMode roundingMode; | ||
| 128 | |||
| 129 | /* ----- Constructors ----- */ | ||
| 130 | |||
| 131 | /** | ||
| 132 | * Constructs a new {@code MathContext} with the specified | ||
| 133 | * precision and the {@link RoundingMode#HALF_UP HALF_UP} rounding | ||
| 134 | * mode. | ||
| 135 | * | ||
| 136 | * @param setPrecision The non-negative {@code int} precision setting. | ||
| 137 | * @throws IllegalArgumentException if the {@code setPrecision} parameter is less | ||
| 138 | * than zero. | ||
| 139 | */ | ||
| 140 | public MathContext(int setPrecision) { | ||
| 141 | this(setPrecision, DEFAULT_ROUNDINGMODE); | ||
| 142 | return; | ||
| 143 | } | ||
| 144 | |||
| 145 | /** | ||
| 146 | * Constructs a new {@code MathContext} with a specified | ||
| 147 | * precision and rounding mode. | ||
| 148 | * | ||
| 149 | * @param setPrecision The non-negative {@code int} precision setting. | ||
| 150 | * @param setRoundingMode The rounding mode to use. | ||
| 151 | * @throws IllegalArgumentException if the {@code setPrecision} parameter is less | ||
| 152 | * than zero. | ||
| 153 | * @throws NullPointerException if the rounding mode argument is {@code null} | ||
| 154 | */ | ||
| 155 | public MathContext(int setPrecision, | ||
| 156 | RoundingMode setRoundingMode) { | ||
| 157 | if (setPrecision < MIN_DIGITS) | ||
| 158 | throw new IllegalArgumentException("Digits < 0"); | ||
| 159 | if (setRoundingMode == null) | ||
| 160 | throw new NullPointerException("null RoundingMode"); | ||
| 161 | |||
| 162 | precision = setPrecision; | ||
| 163 | roundingMode = setRoundingMode; | ||
| 164 | return; | ||
| 165 | } | ||
| 166 | |||
| 167 | /** | ||
| 168 | * Constructs a new {@code MathContext} from a string. | ||
| 169 | * | ||
| 170 | * The string must be in the same format as that produced by the | ||
| 171 | * {@link #toString} method. | ||
| 172 | * | ||
| 173 | * <p>An {@code IllegalArgumentException} is thrown if the precision | ||
| 174 | * section of the string is out of range ({@code < 0}) or the string is | ||
| 175 | * not in the format created by the {@link #toString} method. | ||
| 176 | * | ||
| 177 | * @param val The string to be parsed | ||
| 178 | * @throws IllegalArgumentException if the precision section is out of range | ||
| 179 | * or of incorrect format | ||
| 180 | * @throws NullPointerException if the argument is {@code null} | ||
| 181 | */ | ||
| 182 | public MathContext(String val) { | ||
| 183 | boolean bad = false; | ||
| 184 | int setPrecision; | ||
| 185 | if (val == null) | ||
| 186 | throw new NullPointerException("null String"); | ||
| 187 | try { // any error here is a string format problem | ||
| 188 | if (!val.startsWith("precision=")) throw new RuntimeException(); | ||
| 189 | int fence = val.indexOf(' '); // could be -1 | ||
| 190 | int off = 10; // where value starts | ||
| 191 | setPrecision = Integer.parseInt(val.substring(10, fence)); | ||
| 192 | |||
| 193 | if (!val.startsWith("roundingMode=", fence+1)) | ||
| 194 | throw new RuntimeException(); | ||
| 195 | off = fence + 1 + 13; | ||
| 196 | String str = val.substring(off, val.length()); | ||
| 197 | roundingMode = RoundingMode.valueOf(str); | ||
| 198 | } catch (RuntimeException re) { | ||
| 199 | throw new IllegalArgumentException("bad string format"); | ||
| 200 | } | ||
| 201 | |||
| 202 | if (setPrecision < MIN_DIGITS) | ||
| 203 | throw new IllegalArgumentException("Digits < 0"); | ||
| 204 | // the other parameters cannot be invalid if we got here | ||
| 205 | precision = setPrecision; | ||
| 206 | } | ||
| 207 | |||
| 208 | /** | ||
| 209 | * Returns the {@code precision} setting. | ||
| 210 | * This value is always non-negative. | ||
| 211 | * | ||
| 212 | * @return an {@code int} which is the value of the {@code precision} | ||
| 213 | * setting | ||
| 214 | */ | ||
| 215 | public int getPrecision() { | ||
| 216 | return precision; | ||
| 217 | } | ||
| 218 | |||
| 219 | /** | ||
| 220 | * Returns the roundingMode setting. | ||
| 221 | * This will be one of | ||
| 222 | * {@link RoundingMode#CEILING}, | ||
| 223 | * {@link RoundingMode#DOWN}, | ||
| 224 | * {@link RoundingMode#FLOOR}, | ||
| 225 | * {@link RoundingMode#HALF_DOWN}, | ||
| 226 | * {@link RoundingMode#HALF_EVEN}, | ||
| 227 | * {@link RoundingMode#HALF_UP}, | ||
| 228 | * {@link RoundingMode#UNNECESSARY}, or | ||
| 229 | * {@link RoundingMode#UP}. | ||
| 230 | * | ||
| 231 | * @return a {@code RoundingMode} object which is the value of the | ||
| 232 | * {@code roundingMode} setting | ||
| 233 | */ | ||
| 234 | |||
| 235 | public RoundingMode getRoundingMode() { | ||
| 236 | return roundingMode; | ||
| 237 | } | ||
| 238 | |||
| 239 | /** | ||
| 240 | * Compares this {@code MathContext} with the specified | ||
| 241 | * {@code Object} for equality. | ||
| 242 | * | ||
| 243 | * @param x {@code Object} to which this {@code MathContext} is to | ||
| 244 | * be compared. | ||
| 245 | * @return {@code true} if and only if the specified {@code Object} is | ||
| 246 | * a {@code MathContext} object which has exactly the same | ||
| 247 | * settings as this object | ||
| 248 | */ | ||
| 249 | public boolean equals(Object x){ | ||
| 250 | MathContext mc; | ||
| 251 | if (!(x instanceof MathContext)) | ||
| 252 | return false; | ||
| 253 | mc = (MathContext) x; | ||
| 254 | return mc.precision == this.precision | ||
| 255 | && mc.roundingMode == this.roundingMode; // no need for .equals() | ||
| 256 | } | ||
| 257 | |||
| 258 | /** | ||
| 259 | * Returns the hash code for this {@code MathContext}. | ||
| 260 | * | ||
| 261 | * @return hash code for this {@code MathContext} | ||
| 262 | */ | ||
| 263 | public int hashCode() { | ||
| 264 | return this.precision + roundingMode.hashCode() * 59; | ||
| 265 | } | ||
| 266 | |||
| 267 | /** | ||
| 268 | * Returns the string representation of this {@code MathContext}. | ||
| 269 | * The {@code String} returned represents the settings of the | ||
| 270 | * {@code MathContext} object as two space-delimited words | ||
| 271 | * (separated by a single space character, <tt>'\u0020'</tt>, | ||
| 272 | * and with no leading or trailing white space), as follows: | ||
| 273 | * <ol> | ||
| 274 | * <li> | ||
| 275 | * The string {@code "precision="}, immediately followed | ||
| 276 | * by the value of the precision setting as a numeric string as if | ||
| 277 | * generated by the {@link Integer#toString(int) Integer.toString} | ||
| 278 | * method. | ||
| 279 | * | ||
| 280 | * <li> | ||
| 281 | * The string {@code "roundingMode="}, immediately | ||
| 282 | * followed by the value of the {@code roundingMode} setting as a | ||
| 283 | * word. This word will be the same as the name of the | ||
| 284 | * corresponding public constant in the {@link RoundingMode} | ||
| 285 | * enum. | ||
| 286 | * </ol> | ||
| 287 | * <p> | ||
| 288 | * For example: | ||
| 289 | * <pre> | ||
| 290 | * precision=9 roundingMode=HALF_UP | ||
| 291 | * </pre> | ||
| 292 | * | ||
| 293 | * Additional words may be appended to the result of | ||
| 294 | * {@code toString} in the future if more properties are added to | ||
| 295 | * this class. | ||
| 296 | * | ||
| 297 | * @return a {@code String} representing the context settings | ||
| 298 | */ | ||
| 299 | public java.lang.String toString() { | ||
| 300 | return "precision=" + precision + " " + | ||
| 301 | "roundingMode=" + roundingMode.toString(); | ||
| 302 | } | ||
| 303 | |||
| 304 | // Private methods | ||
| 305 | |||
| 306 | /** | ||
| 307 | * Reconstitute the {@code MathContext} instance from a stream (that is, | ||
| 308 | * deserialize it). | ||
| 309 | * | ||
| 310 | * @param s the stream being read. | ||
| 311 | */ | ||
| 312 | private void readObject(java.io.ObjectInputStream s) | ||
| 313 | throws java.io.IOException, ClassNotFoundException { | ||
| 314 | s.defaultReadObject(); // read in all fields | ||
| 315 | // validate possibly bad fields | ||
| 316 | if (precision < MIN_DIGITS) { | ||
| 317 | String message = "MathContext: invalid digits in stream"; | ||
| 318 | throw new java.io.StreamCorruptedException(message); | ||
| 319 | } | ||
| 320 | if (roundingMode == null) { | ||
| 321 | String message = "MathContext: null roundingMode in stream"; | ||
| 322 | throw new java.io.StreamCorruptedException(message); | ||
| 323 | } | ||
| 324 | } | ||
| 325 | |||
| 326 | } | ||