001 /* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017 018 package org.apache.commons.math3.fraction; 019 020 import java.text.FieldPosition; 021 import java.text.NumberFormat; 022 import java.text.ParsePosition; 023 import java.util.Locale; 024 025 import org.apache.commons.math3.exception.MathIllegalArgumentException; 026 import org.apache.commons.math3.exception.MathParseException; 027 import org.apache.commons.math3.exception.util.LocalizedFormats; 028 029 /** 030 * Formats a Fraction number in proper format or improper format. The number 031 * format for each of the whole number, numerator and, denominator can be 032 * configured. 033 * 034 * @since 1.1 035 * @version $Id: FractionFormat.java 1416643 2012-12-03 19:37:14Z tn $ 036 */ 037 public class FractionFormat extends AbstractFormat { 038 039 /** Serializable version identifier */ 040 private static final long serialVersionUID = 3008655719530972611L; 041 042 /** 043 * Create an improper formatting instance with the default number format 044 * for the numerator and denominator. 045 */ 046 public FractionFormat() { 047 } 048 049 /** 050 * Create an improper formatting instance with a custom number format for 051 * both the numerator and denominator. 052 * @param format the custom format for both the numerator and denominator. 053 */ 054 public FractionFormat(final NumberFormat format) { 055 super(format); 056 } 057 058 /** 059 * Create an improper formatting instance with a custom number format for 060 * the numerator and a custom number format for the denominator. 061 * @param numeratorFormat the custom format for the numerator. 062 * @param denominatorFormat the custom format for the denominator. 063 */ 064 public FractionFormat(final NumberFormat numeratorFormat, 065 final NumberFormat denominatorFormat) { 066 super(numeratorFormat, denominatorFormat); 067 } 068 069 /** 070 * Get the set of locales for which complex formats are available. This 071 * is the same set as the {@link NumberFormat} set. 072 * @return available complex format locales. 073 */ 074 public static Locale[] getAvailableLocales() { 075 return NumberFormat.getAvailableLocales(); 076 } 077 078 /** 079 * This static method calls formatFraction() on a default instance of 080 * FractionFormat. 081 * 082 * @param f Fraction object to format 083 * @return a formatted fraction in proper form. 084 */ 085 public static String formatFraction(Fraction f) { 086 return getImproperInstance().format(f); 087 } 088 089 /** 090 * Returns the default complex format for the current locale. 091 * @return the default complex format. 092 */ 093 public static FractionFormat getImproperInstance() { 094 return getImproperInstance(Locale.getDefault()); 095 } 096 097 /** 098 * Returns the default complex format for the given locale. 099 * @param locale the specific locale used by the format. 100 * @return the complex format specific to the given locale. 101 */ 102 public static FractionFormat getImproperInstance(final Locale locale) { 103 return new FractionFormat(getDefaultNumberFormat(locale)); 104 } 105 106 /** 107 * Returns the default complex format for the current locale. 108 * @return the default complex format. 109 */ 110 public static FractionFormat getProperInstance() { 111 return getProperInstance(Locale.getDefault()); 112 } 113 114 /** 115 * Returns the default complex format for the given locale. 116 * @param locale the specific locale used by the format. 117 * @return the complex format specific to the given locale. 118 */ 119 public static FractionFormat getProperInstance(final Locale locale) { 120 return new ProperFractionFormat(getDefaultNumberFormat(locale)); 121 } 122 123 /** 124 * Create a default number format. The default number format is based on 125 * {@link NumberFormat#getNumberInstance(java.util.Locale)} with the only 126 * customizing is the maximum number of fraction digits, which is set to 0. 127 * @return the default number format. 128 */ 129 protected static NumberFormat getDefaultNumberFormat() { 130 return getDefaultNumberFormat(Locale.getDefault()); 131 } 132 133 /** 134 * Formats a {@link Fraction} object to produce a string. The fraction is 135 * output in improper format. 136 * 137 * @param fraction the object to format. 138 * @param toAppendTo where the text is to be appended 139 * @param pos On input: an alignment field, if desired. On output: the 140 * offsets of the alignment field 141 * @return the value passed in as toAppendTo. 142 */ 143 public StringBuffer format(final Fraction fraction, 144 final StringBuffer toAppendTo, final FieldPosition pos) { 145 146 pos.setBeginIndex(0); 147 pos.setEndIndex(0); 148 149 getNumeratorFormat().format(fraction.getNumerator(), toAppendTo, pos); 150 toAppendTo.append(" / "); 151 getDenominatorFormat().format(fraction.getDenominator(), toAppendTo, 152 pos); 153 154 return toAppendTo; 155 } 156 157 /** 158 * Formats an object and appends the result to a StringBuffer. <code>obj</code> must be either a 159 * {@link Fraction} object or a {@link Number} object. Any other type of 160 * object will result in an {@link IllegalArgumentException} being thrown. 161 * 162 * @param obj the object to format. 163 * @param toAppendTo where the text is to be appended 164 * @param pos On input: an alignment field, if desired. On output: the 165 * offsets of the alignment field 166 * @return the value passed in as toAppendTo. 167 * @see java.text.Format#format(java.lang.Object, java.lang.StringBuffer, java.text.FieldPosition) 168 * @throws FractionConversionException if the number cannot be converted to a fraction 169 * @throws MathIllegalArgumentException if <code>obj</code> is not a valid type. 170 */ 171 @Override 172 public StringBuffer format(final Object obj, 173 final StringBuffer toAppendTo, final FieldPosition pos) 174 throws FractionConversionException, MathIllegalArgumentException { 175 StringBuffer ret = null; 176 177 if (obj instanceof Fraction) { 178 ret = format((Fraction) obj, toAppendTo, pos); 179 } else if (obj instanceof Number) { 180 ret = format(new Fraction(((Number) obj).doubleValue()), toAppendTo, pos); 181 } else { 182 throw new MathIllegalArgumentException(LocalizedFormats.CANNOT_FORMAT_OBJECT_TO_FRACTION); 183 } 184 185 return ret; 186 } 187 188 /** 189 * Parses a string to produce a {@link Fraction} object. 190 * @param source the string to parse 191 * @return the parsed {@link Fraction} object. 192 * @exception MathParseException if the beginning of the specified string 193 * cannot be parsed. 194 */ 195 @Override 196 public Fraction parse(final String source) throws MathParseException { 197 final ParsePosition parsePosition = new ParsePosition(0); 198 final Fraction result = parse(source, parsePosition); 199 if (parsePosition.getIndex() == 0) { 200 throw new MathParseException(source, parsePosition.getErrorIndex(), Fraction.class); 201 } 202 return result; 203 } 204 205 /** 206 * Parses a string to produce a {@link Fraction} object. This method 207 * expects the string to be formatted as an improper fraction. 208 * @param source the string to parse 209 * @param pos input/output parsing parameter. 210 * @return the parsed {@link Fraction} object. 211 */ 212 @Override 213 public Fraction parse(final String source, final ParsePosition pos) { 214 final int initialIndex = pos.getIndex(); 215 216 // parse whitespace 217 parseAndIgnoreWhitespace(source, pos); 218 219 // parse numerator 220 final Number num = getNumeratorFormat().parse(source, pos); 221 if (num == null) { 222 // invalid integer number 223 // set index back to initial, error index should already be set 224 // character examined. 225 pos.setIndex(initialIndex); 226 return null; 227 } 228 229 // parse '/' 230 final int startIndex = pos.getIndex(); 231 final char c = parseNextCharacter(source, pos); 232 switch (c) { 233 case 0 : 234 // no '/' 235 // return num as a fraction 236 return new Fraction(num.intValue(), 1); 237 case '/' : 238 // found '/', continue parsing denominator 239 break; 240 default : 241 // invalid '/' 242 // set index back to initial, error index should be the last 243 // character examined. 244 pos.setIndex(initialIndex); 245 pos.setErrorIndex(startIndex); 246 return null; 247 } 248 249 // parse whitespace 250 parseAndIgnoreWhitespace(source, pos); 251 252 // parse denominator 253 final Number den = getDenominatorFormat().parse(source, pos); 254 if (den == null) { 255 // invalid integer number 256 // set index back to initial, error index should already be set 257 // character examined. 258 pos.setIndex(initialIndex); 259 return null; 260 } 261 262 return new Fraction(num.intValue(), den.intValue()); 263 } 264 265 }