| /* |
| * Copyright (c) 2003, 2021, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| /* |
| * Portions Copyright IBM Corporation, 1997, 2001. All Rights Reserved. |
| */ |
| |
| package java.math; |
| import java.io.*; |
| |
| /** |
| * Immutable objects which encapsulate the context settings which |
| * describe certain rules for numerical operators, such as those |
| * implemented by the {@link BigDecimal} class. |
| * |
| * <p>The base-independent settings are: |
| * <ol> |
| * <li>{@code precision}: |
| * the number of digits to be used for an operation; results are |
| * rounded to this precision |
| * |
| * <li>{@code roundingMode}: |
| * a {@link RoundingMode} object which specifies the algorithm to be |
| * used for rounding. |
| * </ol> |
| * |
| * @see BigDecimal |
| * @see RoundingMode |
| * @author Mike Cowlishaw |
| * @author Joseph D. Darcy |
| * @since 1.5 |
| */ |
| |
| public final class MathContext implements Serializable { |
| |
| /* ----- Constants ----- */ |
| |
| // defaults for constructors |
| private static final int DEFAULT_DIGITS = 9; |
| private static final RoundingMode DEFAULT_ROUNDINGMODE = RoundingMode.HALF_UP; |
| // Smallest values for digits (Maximum is Integer.MAX_VALUE) |
| private static final int MIN_DIGITS = 0; |
| |
| // Serialization version |
| @java.io.Serial |
| private static final long serialVersionUID = 5579720004786848255L; |
| |
| /* ----- Public Properties ----- */ |
| /** |
| * A {@code MathContext} object whose settings have the values |
| * required for unlimited precision arithmetic. |
| * The values of the settings are: {@code precision=0 roundingMode=HALF_UP} |
| */ |
| public static final MathContext UNLIMITED = |
| new MathContext(0, RoundingMode.HALF_UP); |
| |
| /** |
| * A {@code MathContext} object with a precision setting |
| * matching the precision of the IEEE 754-2019 decimal32 format, 7 digits, and a |
| * rounding mode of {@link RoundingMode#HALF_EVEN HALF_EVEN}. |
| * Note the exponent range of decimal32 is <em>not</em> used for |
| * rounding. |
| */ |
| public static final MathContext DECIMAL32 = |
| new MathContext(7, RoundingMode.HALF_EVEN); |
| |
| /** |
| * A {@code MathContext} object with a precision setting |
| * matching the precision of the IEEE 754-2019 decimal64 format, 16 digits, and a |
| * rounding mode of {@link RoundingMode#HALF_EVEN HALF_EVEN}. |
| * Note the exponent range of decimal64 is <em>not</em> used for |
| * rounding. |
| */ |
| public static final MathContext DECIMAL64 = |
| new MathContext(16, RoundingMode.HALF_EVEN); |
| |
| /** |
| * A {@code MathContext} object with a precision setting |
| * matching the precision of the IEEE 754-2019 decimal128 format, 34 digits, and a |
| * rounding mode of {@link RoundingMode#HALF_EVEN HALF_EVEN}. |
| * Note the exponent range of decimal64 is <em>not</em> used for |
| * rounding. |
| */ |
| public static final MathContext DECIMAL128 = |
| new MathContext(34, RoundingMode.HALF_EVEN); |
| |
| /* ----- Shared Properties ----- */ |
| /** |
| * The number of digits to be used for an operation. A value of 0 |
| * indicates that unlimited precision (as many digits as are |
| * required) will be used. Note that leading zeros (in the |
| * coefficient of a number) are never significant. |
| * |
| * <p>{@code precision} will always be non-negative. |
| * |
| * @serial |
| */ |
| final int precision; |
| |
| /** |
| * The rounding algorithm to be used for an operation. |
| * |
| * @see RoundingMode |
| * @serial |
| */ |
| final RoundingMode roundingMode; |
| |
| /* ----- Constructors ----- */ |
| |
| /** |
| * Constructs a new {@code MathContext} with the specified |
| * precision and the {@link RoundingMode#HALF_UP HALF_UP} rounding |
| * mode. |
| * |
| * @param setPrecision The non-negative {@code int} precision setting. |
| * @throws IllegalArgumentException if the {@code setPrecision} parameter is less |
| * than zero. |
| */ |
| public MathContext(int setPrecision) { |
| this(setPrecision, DEFAULT_ROUNDINGMODE); |
| return; |
| } |
| |
| /** |
| * Constructs a new {@code MathContext} with a specified |
| * precision and rounding mode. |
| * |
| * @param setPrecision The non-negative {@code int} precision setting. |
| * @param setRoundingMode The rounding mode to use. |
| * @throws IllegalArgumentException if the {@code setPrecision} parameter is less |
| * than zero. |
| * @throws NullPointerException if the rounding mode argument is {@code null} |
| */ |
| public MathContext(int setPrecision, |
| RoundingMode setRoundingMode) { |
| if (setPrecision < MIN_DIGITS) |
| throw new IllegalArgumentException("Digits < 0"); |
| if (setRoundingMode == null) |
| throw new NullPointerException("null RoundingMode"); |
| |
| precision = setPrecision; |
| roundingMode = setRoundingMode; |
| return; |
| } |
| |
| /** |
| * Constructs a new {@code MathContext} from a string. |
| * |
| * The string must be in the same format as that produced by the |
| * {@link #toString} method. |
| * |
| * <p>An {@code IllegalArgumentException} is thrown if the precision |
| * section of the string is out of range ({@code < 0}) or the string is |
| * not in the format created by the {@link #toString} method. |
| * |
| * @param val The string to be parsed |
| * @throws IllegalArgumentException if the precision section is out of range |
| * or of incorrect format |
| * @throws NullPointerException if the argument is {@code null} |
| */ |
| public MathContext(String val) { |
| boolean bad = false; |
| int setPrecision; |
| if (val == null) |
| throw new NullPointerException("null String"); |
| try { // any error here is a string format problem |
| if (!val.startsWith("precision=")) throw new RuntimeException(); |
| int fence = val.indexOf(' '); // could be -1 |
| int off = 10; // where value starts |
| setPrecision = Integer.parseInt(val.substring(10, fence)); |
| |
| if (!val.startsWith("roundingMode=", fence+1)) |
| throw new RuntimeException(); |
| off = fence + 1 + 13; |
| String str = val.substring(off, val.length()); |
| roundingMode = RoundingMode.valueOf(str); |
| } catch (RuntimeException re) { |
| throw new IllegalArgumentException("bad string format"); |
| } |
| |
| if (setPrecision < MIN_DIGITS) |
| throw new IllegalArgumentException("Digits < 0"); |
| // the other parameters cannot be invalid if we got here |
| precision = setPrecision; |
| } |
| |
| /** |
| * Returns the {@code precision} setting. |
| * This value is always non-negative. |
| * |
| * @return an {@code int} which is the value of the {@code precision} |
| * setting |
| */ |
| public int getPrecision() { |
| return precision; |
| } |
| |
| /** |
| * Returns the roundingMode setting. |
| * This will be one of |
| * {@link RoundingMode#CEILING}, |
| * {@link RoundingMode#DOWN}, |
| * {@link RoundingMode#FLOOR}, |
| * {@link RoundingMode#HALF_DOWN}, |
| * {@link RoundingMode#HALF_EVEN}, |
| * {@link RoundingMode#HALF_UP}, |
| * {@link RoundingMode#UNNECESSARY}, or |
| * {@link RoundingMode#UP}. |
| * |
| * @return a {@code RoundingMode} object which is the value of the |
| * {@code roundingMode} setting |
| */ |
| |
| public RoundingMode getRoundingMode() { |
| return roundingMode; |
| } |
| |
| /** |
| * Compares this {@code MathContext} with the specified |
| * {@code Object} for equality. |
| * |
| * @param x {@code Object} to which this {@code MathContext} is to |
| * be compared. |
| * @return {@code true} if and only if the specified {@code Object} is |
| * a {@code MathContext} object which has exactly the same |
| * settings as this object |
| */ |
| public boolean equals(Object x){ |
| if (!(x instanceof MathContext mc)) |
| return false; |
| return mc.precision == this.precision |
| && mc.roundingMode == this.roundingMode; // no need for .equals() |
| } |
| |
| /** |
| * Returns the hash code for this {@code MathContext}. |
| * |
| * @return hash code for this {@code MathContext} |
| */ |
| public int hashCode() { |
| return this.precision + roundingMode.hashCode() * 59; |
| } |
| |
| /** |
| * Returns the string representation of this {@code MathContext}. |
| * The {@code String} returned represents the settings of the |
| * {@code MathContext} object as two space-delimited words |
| * (separated by a single space character, <code>'\u0020'</code>, |
| * and with no leading or trailing white space), as follows: |
| * <ol> |
| * <li> |
| * The string {@code "precision="}, immediately followed |
| * by the value of the precision setting as a numeric string as if |
| * generated by the {@link Integer#toString(int) Integer.toString} |
| * method. |
| * |
| * <li> |
| * The string {@code "roundingMode="}, immediately |
| * followed by the value of the {@code roundingMode} setting as a |
| * word. This word will be the same as the name of the |
| * corresponding public constant in the {@link RoundingMode} |
| * enum. |
| * </ol> |
| * <p> |
| * For example: |
| * <pre> |
| * precision=9 roundingMode=HALF_UP |
| * </pre> |
| * |
| * Additional words may be appended to the result of |
| * {@code toString} in the future if more properties are added to |
| * this class. |
| * |
| * @return a {@code String} representing the context settings |
| */ |
| public java.lang.String toString() { |
| return "precision=" + precision + " " + |
| "roundingMode=" + roundingMode.toString(); |
| } |
| |
| // Private methods |
| |
| /** |
| * Reconstitute the {@code MathContext} instance from a stream (that is, |
| * deserialize it). |
| * |
| * @param s the stream being read. |
| * @throws IOException if an I/O error occurs |
| * @throws ClassNotFoundException if a serialized class cannot be loaded |
| */ |
| @java.io.Serial |
| private void readObject(java.io.ObjectInputStream s) |
| throws java.io.IOException, ClassNotFoundException { |
| s.defaultReadObject(); // read in all fields |
| // validate possibly bad fields |
| if (precision < MIN_DIGITS) { |
| String message = "MathContext: invalid digits in stream"; |
| throw new java.io.StreamCorruptedException(message); |
| } |
| if (roundingMode == null) { |
| String message = "MathContext: null roundingMode in stream"; |
| throw new java.io.StreamCorruptedException(message); |
| } |
| } |
| |
| } |
