All Downloads are FREE. Search and download functionalities are using the official Maven repository.

org.apache.commons.math.fraction.ProperBigFractionFormat Maven / Gradle / Ivy

Go to download

The Math project is a library of lightweight, self-contained mathematics and statistics components addressing the most common practical problems not immediately available in the Java programming language or commons-lang.

There is a newer version: 2.2
Show newest version
/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.math.BigInteger;
import java.text.FieldPosition;
import java.text.NumberFormat;
import java.text.ParsePosition;

import org.apache.commons.math.MathRuntimeException;

/**
 * Formats a BigFraction number in proper format.  The number format for each of
 * the whole number, numerator and, denominator can be configured.
 * 

* Minus signs are only allowed in the whole number part - i.e., * "-3 1/2" is legitimate and denotes -7/2, but "-3 -1/2" is invalid and * will result in a ParseException.

* * @since 1.1 * @version $Revision: 762087 $ $Date: 2009-04-05 10:20:18 -0400 (Sun, 05 Apr 2009) $ */ public class ProperBigFractionFormat extends BigFractionFormat { /** Serializable version identifier */ private 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 ProperBigFractionFormat() { 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 ProperBigFractionFormat(final 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 ProperBigFractionFormat(final NumberFormat wholeFormat, final NumberFormat numeratorFormat, final NumberFormat denominatorFormat) { super(numeratorFormat, denominatorFormat); setWholeFormat(wholeFormat); } /** * Formats a {@link BigFraction} object to produce a string. The BigFraction * 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. */ @Override public StringBuffer format(final BigFraction fraction, final StringBuffer toAppendTo, final FieldPosition pos) { pos.setBeginIndex(0); pos.setEndIndex(0); BigInteger num = fraction.getNumerator(); BigInteger den = fraction.getDenominator(); BigInteger whole = num.divide(den); num = num.remainder(den); if (!BigInteger.ZERO.equals(whole)) { getWholeFormat().format(whole, toAppendTo, pos); toAppendTo.append(' '); if (num.compareTo(BigInteger.ZERO) < 0) { num = num.negate(); } } 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 BigFraction} object. This method * expects the string to be formatted as a proper BigFraction. *

* Minus signs are only allowed in the whole number part - i.e., * "-3 1/2" is legitimate and denotes -7/2, but "-3 -1/2" is invalid and * will result in a ParseException.

* * @param source the string to parse * @param pos input/ouput parsing parameter. * @return the parsed {@link BigFraction} object. */ @Override public BigFraction parse(final String source, final ParsePosition pos) { // try to parse improper BigFraction BigFraction ret = super.parse(source, pos); if (ret != null) { return ret; } final int initialIndex = pos.getIndex(); // parse whitespace parseAndIgnoreWhitespace(source, pos); // parse whole BigInteger whole = parseNextBigInteger(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 BigInteger num = parseNextBigInteger(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; } if (num.compareTo(BigInteger.ZERO) < 0) { // minus signs should be leading, invalid expression pos.setIndex(initialIndex); return null; } // parse '/' final int startIndex = pos.getIndex(); final char c = parseNextCharacter(source, pos); switch (c) { case 0 : // no '/' // return num as a BigFraction return new BigFraction(num); 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 final BigInteger den = parseNextBigInteger(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; } if (den.compareTo(BigInteger.ZERO) < 0) { // minus signs must be leading, invalid pos.setIndex(initialIndex); return null; } boolean wholeIsNeg = whole.compareTo(BigInteger.ZERO) < 0; if (wholeIsNeg) { whole = whole.negate(); } num = whole.multiply(den).add(num); if (wholeIsNeg) { num = num.negate(); } return new BigFraction(num, den); } /** * Modify the whole format. * @param format The new whole format value. * @throws IllegalArgumentException if format is * null. */ public void setWholeFormat(final NumberFormat format) { if (format == null) { throw MathRuntimeException.createIllegalArgumentException( "whole format can not be null"); } this.wholeFormat = format; } }




© 2015 - 2024 Weber Informatics LLC | Privacy Policy