/* | |
* Copyright 2005 The Apache Software Foundation. | |
* | |
* Licensed under the Apache License, Version 2.0 (the "License"); | |
* you may not use this file except in compliance with the License. | |
* You may obtain a copy of the License at | |
* | |
* http://www.apache.org/licenses/LICENSE-2.0 | |
* | |
* Unless required by applicable law or agreed to in writing, software | |
* distributed under the License is distributed on an "AS IS" BASIS, | |
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
* See the License for the specific language governing permissions and | |
* limitations under the License. | |
*/ | |
package org.apache.commons.math.fraction; | |
import java.text.FieldPosition; | |
import java.text.NumberFormat; | |
import java.text.ParsePosition; | |
import org.apache.commons.math.util.MathUtils; | |
/** | |
* Formats a Fraction number in proper format. The number format for each of | |
* the whole number, numerator and, denominator can be configured. | |
* | |
* @since 1.1 | |
* @version $Revision$ $Date$ | |
*/ | |
public class ProperFractionFormat extends FractionFormat { | |
/** Serializable version identifier */ | |
static final long serialVersionUID = -6337346779577272307L; | |
/** The format used for the whole number. */ | |
private NumberFormat wholeFormat; | |
/** | |
* Create a proper formatting instance with the default number format for | |
* the whole, numerator, and denominator. | |
*/ | |
public ProperFractionFormat() { | |
this(getDefaultNumberFormat()); | |
} | |
/** | |
* Create a proper formatting instance with a custom number format for the | |
* whole, numerator, and denominator. | |
* @param format the custom format for the whole, numerator, and | |
* denominator. | |
*/ | |
public ProperFractionFormat(NumberFormat format) { | |
this(format, (NumberFormat)format.clone(), (NumberFormat)format.clone()); | |
} | |
/** | |
* Create a proper formatting instance with a custom number format for each | |
* of the whole, numerator, and denominator. | |
* @param wholeFormat the custom format for the whole. | |
* @param numeratorFormat the custom format for the numerator. | |
* @param denominatorFormat the custom format for the denominator. | |
*/ | |
public ProperFractionFormat(NumberFormat wholeFormat, | |
NumberFormat numeratorFormat, | |
NumberFormat denominatorFormat) | |
{ | |
super(numeratorFormat, denominatorFormat); | |
setWholeFormat(wholeFormat); | |
} | |
/** | |
* Formats a {@link Fraction} object to produce a string. The fraction | |
* is output in proper format. | |
* | |
* @param fraction the object to format. | |
* @param toAppendTo where the text is to be appended | |
* @param pos On input: an alignment field, if desired. On output: the | |
* offsets of the alignment field | |
* @return the value passed in as toAppendTo. | |
*/ | |
public StringBuffer format(Fraction fraction, StringBuffer toAppendTo, | |
FieldPosition pos) { | |
pos.setBeginIndex(0); | |
pos.setEndIndex(0); | |
int num = fraction.getNumerator(); | |
int den = fraction.getDenominator(); | |
int whole = num / den; | |
num = num % den; | |
if (whole != 0) { | |
getWholeFormat().format(whole, toAppendTo, pos); | |
toAppendTo.append(' '); | |
num = Math.abs(num); | |
} | |
getNumeratorFormat().format(num, toAppendTo, pos); | |
toAppendTo.append(" / "); | |
getDenominatorFormat().format(den, toAppendTo, | |
pos); | |
return toAppendTo; | |
} | |
/** | |
* Access the whole format. | |
* @return the whole format. | |
*/ | |
public NumberFormat getWholeFormat() { | |
return wholeFormat; | |
} | |
/** | |
* Parses a string to produce a {@link Fraction} object. This method | |
* expects the string to be formatted as a proper fraction. | |
* @param source the string to parse | |
* @param pos input/ouput parsing parameter. | |
* @return the parsed {@link Fraction} object. | |
*/ | |
public Fraction parse(String source, ParsePosition pos) { | |
// try to parse improper fraction | |
Fraction ret = super.parse(source, pos); | |
if (ret != null) { | |
return ret; | |
} | |
int initialIndex = pos.getIndex(); | |
// parse whitespace | |
parseAndIgnoreWhitespace(source, pos); | |
// parse whole | |
Number whole = getWholeFormat().parse(source, pos); | |
if (whole == null) { | |
// invalid integer number | |
// set index back to initial, error index should already be set | |
// character examined. | |
pos.setIndex(initialIndex); | |
return null; | |
} | |
// parse whitespace | |
parseAndIgnoreWhitespace(source, pos); | |
// parse numerator | |
Number num = getNumeratorFormat().parse(source, pos); | |
if (num == null) { | |
// invalid integer number | |
// set index back to initial, error index should already be set | |
// character examined. | |
pos.setIndex(initialIndex); | |
return null; | |
} | |
// parse '/' | |
int startIndex = pos.getIndex(); | |
char c = parseNextCharacter(source, pos); | |
switch (c) { | |
case 0 : | |
// no '/' | |
// return num as a fraction | |
return new Fraction(num.intValue(), 1); | |
case '/' : | |
// found '/', continue parsing denominator | |
break; | |
default : | |
// invalid '/' | |
// set index back to initial, error index should be the last | |
// character examined. | |
pos.setIndex(initialIndex); | |
pos.setErrorIndex(startIndex); | |
return null; | |
} | |
// parse whitespace | |
parseAndIgnoreWhitespace(source, pos); | |
// parse denominator | |
Number den = getDenominatorFormat().parse(source, pos); | |
if (den == null) { | |
// invalid integer number | |
// set index back to initial, error index should already be set | |
// character examined. | |
pos.setIndex(initialIndex); | |
return null; | |
} | |
int w = whole.intValue(); | |
int n = num.intValue(); | |
int d = den.intValue(); | |
return new Fraction(((Math.abs(w) * d) + n) * MathUtils.sign(w), d); | |
} | |
/** | |
* Modify the whole format. | |
* @param format The new whole format value. | |
* @throws IllegalArgumentException if <code>format</code> is | |
* <code>null</code>. | |
*/ | |
public void setWholeFormat(NumberFormat format) { | |
if (format == null) { | |
throw new IllegalArgumentException( | |
"whole format can not be null."); | |
} | |
this.wholeFormat = format; | |
} | |
} |