Source for java.math.MathContext

 1:  /* MathContext.java -- 
 2:  Copyright (C) 1999, 2000, 2002, 2004, 2005 Free Software Foundation, Inc.
 3: 
 4: This file is part of GNU Classpath.
 5: 
 6: GNU Classpath is free software; you can redistribute it and/or modify
 7: it under the terms of the GNU General Public License as published by
 8: the Free Software Foundation; either version 2, or (at your option)
 9: any later version.
 10: 
 11: GNU Classpath is distributed in the hope that it will be useful, but
 12: WITHOUT ANY WARRANTY; without even the implied warranty of
 13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 14: General Public License for more details.
 15: 
 16: You should have received a copy of the GNU General Public License
 17: along with GNU Classpath; see the file COPYING. If not, write to the
 18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 19: 02110-1301 USA.
 20: 
 21: Linking this library statically or dynamically with other modules is
 22: making a combined work based on this library. Thus, the terms and
 23: conditions of the GNU General Public License cover the whole
 24: combination.
 25: 
 26: As a special exception, the copyright holders of this library give you
 27: permission to link this library with independent modules to produce an
 28: executable, regardless of the license terms of these independent
 29: modules, and to copy and distribute the resulting executable under
 30: terms of your choice, provided that you also meet, for each linked
 31: independent module, the terms and conditions of the license of that
 32: module. An independent module is a module which is not derived from
 33: or based on this library. If you modify this library, you may extend
 34: this exception to your version of the library, but you are not
 35: obligated to do so. If you do not wish to do so, delete this
 36: exception statement from your version. */
 37: 
 38: 
 39:  package java.math;
 40: 
 41:  import java.io.Serializable;
 42: 
 43:  /**
 44:  * Immutable objects describing settings such as rounding mode and digit
 45:  * precision for numerical operations such as those in the BigDecimal class.
 46:  * @author Anthony Balkissoon abalkiss at redhat dot com
 47:  *
 48:  */
 49:  public final class MathContext implements Serializable
 50: {
 51:  /** A MathContext for unlimited precision arithmetic * */
 52:  public static final MathContext UNLIMITED = 
 53:  new MathContext(0, RoundingMode.HALF_UP);
 54:  
 55:  /**
 56:  * A MathContext for the IEEE 754R Decimal32 format - 7 digit preicision and
 57:  * HALF_EVEN rounding.
 58:  */
 59:  public static final MathContext DECIMAL32 = 
 60:  new MathContext(7, RoundingMode.HALF_EVEN);
 61:  
 62:  /**
 63:  * A MathContext for the IEEE 754R Decimal64 format - 16 digit preicision and
 64:  * HALF_EVEN rounding.
 65:  */
 66:  public static final MathContext DECIMAL64 = 
 67:  new MathContext(16, RoundingMode.HALF_EVEN);
 68:  
 69:  /**
 70:  * A MathContext for the IEEE 754R Decimal128 format - 34 digit preicision and
 71:  * HALF_EVEN rounding.
 72:  */
 73:  public static final MathContext DECIMAL128 = 
 74:  new MathContext(34, RoundingMode.HALF_EVEN);
 75:  
 76:  /**
 77:  * This is the serialVersionUID reported here:
 78:  * java.sun.com/j2se/1.5.0/docs/api/serialized-form.html#java.math.MathContext
 79:  */
 80:  private static final long serialVersionUID = 5579720004786848255L;
 81:  
 82:  private int precision;
 83:  
 84:  private RoundingMode roundMode;
 85:  
 86:  /**
 87:  * Constructs a new MathContext with the specified precision and with HALF_UP
 88:  * rounding.
 89:  * @param setPrecision the precision for the new MathContext
 90:  * 
 91:  * @throws IllegalArgumentException if precision is < 0.
 92:  */
 93:  public MathContext(int setPrecision)
 94:  {
 95:  this(setPrecision, RoundingMode.HALF_UP);
 96:  }
 97:  
 98:  /**
 99:  * 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: }