001 /* MathContext.java -- 002 Copyright (C) 1999, 2000, 2002, 2004, 2005 Free Software Foundation, Inc. 003 004 This file is part of GNU Classpath. 005 006 GNU Classpath is free software; you can redistribute it and/or modify 007 it under the terms of the GNU General Public License as published by 008 the Free Software Foundation; either version 2, or (at your option) 009 any later version. 010 011 GNU Classpath is distributed in the hope that it will be useful, but 012 WITHOUT ANY WARRANTY; without even the implied warranty of 013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 014 General Public License for more details. 015 016 You should have received a copy of the GNU General Public License 017 along with GNU Classpath; see the file COPYING. If not, write to the 018 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 019 02110-1301 USA. 020 021 Linking this library statically or dynamically with other modules is 022 making a combined work based on this library. Thus, the terms and 023 conditions of the GNU General Public License cover the whole 024 combination. 025 026 As a special exception, the copyright holders of this library give you 027 permission to link this library with independent modules to produce an 028 executable, regardless of the license terms of these independent 029 modules, and to copy and distribute the resulting executable under 030 terms of your choice, provided that you also meet, for each linked 031 independent module, the terms and conditions of the license of that 032 module. An independent module is a module which is not derived from 033 or based on this library. If you modify this library, you may extend 034 this exception to your version of the library, but you are not 035 obligated to do so. If you do not wish to do so, delete this 036 exception statement from your version. */ 037 038 039 package java.math; 040 041 import java.io.Serializable; 042 043 /** 044 * Immutable objects describing settings such as rounding mode and digit 045 * precision for numerical operations such as those in the BigDecimal class. 046 * @author Anthony Balkissoon abalkiss at redhat dot com 047 * 048 */ 049 public final class MathContext implements Serializable 050 { 051 /** A MathContext for unlimited precision arithmetic * */ 052 public static final MathContext UNLIMITED = 053 new MathContext(0, RoundingMode.HALF_UP); 054 055 /** 056 * A MathContext for the IEEE 754R Decimal32 format - 7 digit preicision and 057 * HALF_EVEN rounding. 058 */ 059 public static final MathContext DECIMAL32 = 060 new MathContext(7, RoundingMode.HALF_EVEN); 061 062 /** 063 * A MathContext for the IEEE 754R Decimal64 format - 16 digit preicision and 064 * HALF_EVEN rounding. 065 */ 066 public static final MathContext DECIMAL64 = 067 new MathContext(16, RoundingMode.HALF_EVEN); 068 069 /** 070 * A MathContext for the IEEE 754R Decimal128 format - 34 digit preicision and 071 * HALF_EVEN rounding. 072 */ 073 public static final MathContext DECIMAL128 = 074 new MathContext(34, RoundingMode.HALF_EVEN); 075 076 /** 077 * This is the serialVersionUID reported here: 078 * java.sun.com/j2se/1.5.0/docs/api/serialized-form.html#java.math.MathContext 079 */ 080 private static final long serialVersionUID = 5579720004786848255L; 081 082 private int precision; 083 084 private RoundingMode roundMode; 085 086 /** 087 * Constructs a new MathContext with the specified precision and with HALF_UP 088 * rounding. 089 * @param setPrecision the precision for the new MathContext 090 * 091 * @throws IllegalArgumentException if precision is < 0. 092 */ 093 public MathContext(int setPrecision) 094 { 095 this(setPrecision, RoundingMode.HALF_UP); 096 } 097 098 /** 099 * Constructs a new MathContext with the specified precision and rounding 100 * mode. 101 * @param setPrecision the precision 102 * @param setRoundingMode the rounding mode 103 * 104 * @throws IllegalArgumentException if precision is < 0. 105 */ 106 public MathContext(int setPrecision, RoundingMode setRoundingMode) 107 { 108 if (setPrecision < 0) 109 throw new IllegalArgumentException("Precision cannot be less than zero."); 110 precision = setPrecision; 111 roundMode = setRoundingMode; 112 } 113 114 /** 115 * Constructs a MathContext from a String that has the same form as one 116 * produced by the toString() method. 117 * @param val 118 * 119 * @throws IllegalArgumentException if the String is not in the correct 120 * format or if the precision specified is < 0. 121 */ 122 public MathContext(String val) 123 { 124 try 125 { 126 int roundingModeIndex = val.indexOf("roundingMode", 10); 127 precision = Integer.parseInt(val.substring(10, roundingModeIndex - 1)); 128 roundMode = RoundingMode.valueOf(val.substring(roundingModeIndex + 13)); 129 } 130 catch (NumberFormatException nfe) 131 { 132 throw new IllegalArgumentException("String not in correct format"); 133 } 134 catch (IllegalArgumentException iae) 135 { 136 throw new IllegalArgumentException("String not in correct format"); 137 } 138 if (precision < 0) 139 throw new IllegalArgumentException("Precision cannot be less than 0."); 140 } 141 142 /** 143 * Returns true if x is a MathContext and has the same precision setting 144 * and rounding mode as this MathContext. 145 * 146 * @return true if the above conditions hold 147 */ 148 public boolean equals(Object x) 149 { 150 if (!(x instanceof MathContext)) 151 return false; 152 MathContext mc = (MathContext)x; 153 return mc.precision == this.precision 154 && mc.roundMode.equals(this.roundMode); 155 } 156 157 /** 158 * Returns the precision setting. 159 * @return the precision setting. 160 */ 161 public int getPrecision() 162 { 163 return precision; 164 } 165 166 /** 167 * Returns the rounding mode setting. This will be one of 168 * RoundingMode.CEILING, RoundingMode.DOWN, RoundingMode.FLOOR, 169 * RoundingMode.HALF_DOWN, RoundingMode.HALF_EVEN, RoundingMode.HALF_UP, 170 * RoundingMode.UNNECESSARY, or RoundingMode.UP. 171 * @return the rounding mode setting. 172 */ 173 public RoundingMode getRoundingMode() 174 { 175 return roundMode; 176 } 177 178 /** 179 * Returns "precision=p roundingMode=MODE" where p is an int giving the 180 * precision and MODE is UP, DOWN, HALF_UP, HALF_DOWN, HALF_EVEN, CEILING, 181 * FLOOR, or UNNECESSARY corresponding to rounding modes. 182 * 183 * @return a String describing this MathContext 184 */ 185 public String toString() 186 { 187 return "precision="+precision+" roundingMode="+roundMode; 188 } 189 190 /** 191 * Returns the hashcode for this MathContext. 192 * @return the hashcode for this MathContext. 193 */ 194 public int hashCode() 195 { 196 return precision ^ roundMode.hashCode(); 197 } 198 }