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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 | +} | |