src/main/java/org/apache/commons/math/fraction/FractionFormat.java - platform/external/apache-commons-math - Git at Google

 /*
  * 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.text.FieldPosition;
 import java.text.NumberFormat;
 import java.text.ParseException;
 import java.text.ParsePosition;
 import java.util.Locale;

 import org.apache.commons.math.ConvergenceException;
 import org.apache.commons.math.MathRuntimeException;
 import org.apache.commons.math.exception.util.LocalizedFormats;

 /**
  * Formats a Fraction number in proper format or improper format.  The number
  * format for each of the whole number, numerator and, denominator can be
  * configured.
  *
  * @since 1.1
  * @version $Revision: 983921 $ $Date: 2010-08-10 12:46:06 +0200 (mar. 10 août 2010) $
  */
 public class FractionFormat extends AbstractFormat {

     /** Serializable version identifier */
     private static final long serialVersionUID = 3008655719530972611L;

     /**
      * Create an improper formatting instance with the default number format
      * for the numerator and denominator.
      */
     public FractionFormat() {
     }

     /**
      * Create an improper formatting instance with a custom number format for
      * both the numerator and denominator.
      * @param format the custom format for both the numerator and denominator.
      */
     public FractionFormat(final NumberFormat format) {
         super(format);
     }

     /**
      * Create an improper formatting instance with a custom number format for
      * the numerator and a custom number format for the denominator.
      * @param numeratorFormat the custom format for the numerator.
      * @param denominatorFormat the custom format for the denominator.
      */
     public FractionFormat(final NumberFormat numeratorFormat,
                           final NumberFormat denominatorFormat) {
         super(numeratorFormat, denominatorFormat);
     }

     /**
      * Get the set of locales for which complex formats are available.  This
      * is the same set as the {@link NumberFormat} set.
      * @return available complex format locales.
      */
     public static Locale[] getAvailableLocales() {
         return NumberFormat.getAvailableLocales();
     }

     /**
      * This static method calls formatFraction() on a default instance of
      * FractionFormat.
      *
      * @param f Fraction object to format
      * @return A formatted fraction in proper form.
      */
     public static String formatFraction(Fraction f) {
         return getImproperInstance().format(f);
     }

     /**
      * Returns the default complex format for the current locale.
      * @return the default complex format.
      */
     public static FractionFormat getImproperInstance() {
         return getImproperInstance(Locale.getDefault());
     }

     /**
      * Returns the default complex format for the given locale.
      * @param locale the specific locale used by the format.
      * @return the complex format specific to the given locale.
      */
     public static FractionFormat getImproperInstance(final Locale locale) {
         return new FractionFormat(getDefaultNumberFormat(locale));
     }

     /**
      * Returns the default complex format for the current locale.
      * @return the default complex format.
      */
     public static FractionFormat getProperInstance() {
         return getProperInstance(Locale.getDefault());
     }

     /**
      * Returns the default complex format for the given locale.
      * @param locale the specific locale used by the format.
      * @return the complex format specific to the given locale.
      */
     public static FractionFormat getProperInstance(final Locale locale) {
         return new ProperFractionFormat(getDefaultNumberFormat(locale));
     }

     /**
      * Create a default number format.  The default number format is based on
      * {@link NumberFormat#getNumberInstance(java.util.Locale)} with the only
      * customizing is the maximum number of fraction digits, which is set to 0.
      * @return the default number format.
      */
     protected static NumberFormat getDefaultNumberFormat() {
         return getDefaultNumberFormat(Locale.getDefault());
     }

     /**
      * Formats a {@link Fraction} object to produce a string.  The fraction is
      * output in improper 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(final Fraction fraction,
                                final StringBuffer toAppendTo, final FieldPosition pos) {

         pos.setBeginIndex(0);
         pos.setEndIndex(0);

         getNumeratorFormat().format(fraction.getNumerator(), toAppendTo, pos);
         toAppendTo.append(" / ");
         getDenominatorFormat().format(fraction.getDenominator(), toAppendTo,
             pos);

         return toAppendTo;
     }

     /**
      * Formats an object and appends the result to a StringBuffer. <code>obj</code> must be either a
      * {@link Fraction} object or a {@link Number} object.  Any other type of
      * object will result in an {@link IllegalArgumentException} being thrown.
      *
      * @param obj 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.
      * @see java.text.Format#format(java.lang.Object, java.lang.StringBuffer, java.text.FieldPosition)
      * @throws IllegalArgumentException is <code>obj</code> is not a valid type.
      */
     @Override
     public StringBuffer format(final Object obj,
                                final StringBuffer toAppendTo, final FieldPosition pos) {
         StringBuffer ret = null;

         if (obj instanceof Fraction) {
             ret = format((Fraction) obj, toAppendTo, pos);
         } else if (obj instanceof Number) {
             try {
                 ret = format(new Fraction(((Number) obj).doubleValue()),
                              toAppendTo, pos);
             } catch (ConvergenceException ex) {
                 throw MathRuntimeException.createIllegalArgumentException(
                     LocalizedFormats.CANNOT_CONVERT_OBJECT_TO_FRACTION,
                     ex.getLocalizedMessage());
             }
         } else {
             throw MathRuntimeException.createIllegalArgumentException(
                 LocalizedFormats.CANNOT_FORMAT_OBJECT_TO_FRACTION);
         }

         return ret;
     }

     /**
      * Parses a string to produce a {@link Fraction} object.
      * @param source the string to parse
      * @return the parsed {@link Fraction} object.
      * @exception ParseException if the beginning of the specified string
      *            cannot be parsed.
      */
     @Override
     public Fraction parse(final String source) throws ParseException {
         final ParsePosition parsePosition = new ParsePosition(0);
         final Fraction result = parse(source, parsePosition);
         if (parsePosition.getIndex() == 0) {
             throw MathRuntimeException.createParseException(
                     parsePosition.getErrorIndex(),
                     LocalizedFormats.UNPARSEABLE_FRACTION_NUMBER, source);
         }
         return result;
     }

     /**
      * Parses a string to produce a {@link Fraction} object.  This method
      * expects the string to be formatted as an improper fraction.
      * @param source the string to parse
      * @param pos input/ouput parsing parameter.
      * @return the parsed {@link Fraction} object.
      */
     @Override
     public Fraction parse(final String source, final ParsePosition pos) {
         final int initialIndex = pos.getIndex();

         // parse whitespace
         parseAndIgnoreWhitespace(source, pos);

         // parse numerator
         final 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 '/'
         final int startIndex = pos.getIndex();
         final 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
         final 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;
         }

         return new Fraction(num.intValue(), den.intValue());
     }

 }
	/*
	* 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.text.FieldPosition;
	import java.text.NumberFormat;
	import java.text.ParseException;
	import java.text.ParsePosition;
	import java.util.Locale;

	import org.apache.commons.math.ConvergenceException;
	import org.apache.commons.math.MathRuntimeException;
	import org.apache.commons.math.exception.util.LocalizedFormats;

	/**
	* Formats a Fraction number in proper format or improper format. The number
	* format for each of the whole number, numerator and, denominator can be
	* configured.
	*
	* @since 1.1
	* @version $Revision: 983921 $ $Date: 2010-08-10 12:46:06 +0200 (mar. 10 août 2010) $
	*/
	public class FractionFormat extends AbstractFormat {

	/** Serializable version identifier */
	private static final long serialVersionUID = 3008655719530972611L;

	/**
	* Create an improper formatting instance with the default number format
	* for the numerator and denominator.
	*/
	public FractionFormat() {
	}

	/**
	* Create an improper formatting instance with a custom number format for
	* both the numerator and denominator.
	* @param format the custom format for both the numerator and denominator.
	*/
	public FractionFormat(final NumberFormat format) {
	super(format);
	}

	/**
	* Create an improper formatting instance with a custom number format for
	* the numerator and a custom number format for the denominator.
	* @param numeratorFormat the custom format for the numerator.
	* @param denominatorFormat the custom format for the denominator.
	*/
	public FractionFormat(final NumberFormat numeratorFormat,
	final NumberFormat denominatorFormat) {
	super(numeratorFormat, denominatorFormat);
	}

	/**
	* Get the set of locales for which complex formats are available. This
	* is the same set as the {@link NumberFormat} set.
	* @return available complex format locales.
	*/
	public static Locale[] getAvailableLocales() {
	return NumberFormat.getAvailableLocales();
	}

	/**
	* This static method calls formatFraction() on a default instance of
	* FractionFormat.
	*
	* @param f Fraction object to format
	* @return A formatted fraction in proper form.
	*/
	public static String formatFraction(Fraction f) {
	return getImproperInstance().format(f);
	}

	/**
	* Returns the default complex format for the current locale.
	* @return the default complex format.
	*/
	public static FractionFormat getImproperInstance() {
	return getImproperInstance(Locale.getDefault());
	}

	/**
	* Returns the default complex format for the given locale.
	* @param locale the specific locale used by the format.
	* @return the complex format specific to the given locale.
	*/
	public static FractionFormat getImproperInstance(final Locale locale) {
	return new FractionFormat(getDefaultNumberFormat(locale));
	}

	/**
	* Returns the default complex format for the current locale.
	* @return the default complex format.
	*/
	public static FractionFormat getProperInstance() {
	return getProperInstance(Locale.getDefault());
	}

	/**
	* Returns the default complex format for the given locale.
	* @param locale the specific locale used by the format.
	* @return the complex format specific to the given locale.
	*/
	public static FractionFormat getProperInstance(final Locale locale) {
	return new ProperFractionFormat(getDefaultNumberFormat(locale));
	}

	/**
	* Create a default number format. The default number format is based on
	* {@link NumberFormat#getNumberInstance(java.util.Locale)} with the only
	* customizing is the maximum number of fraction digits, which is set to 0.
	* @return the default number format.
	*/
	protected static NumberFormat getDefaultNumberFormat() {
	return getDefaultNumberFormat(Locale.getDefault());
	}

	/**
	* Formats a {@link Fraction} object to produce a string. The fraction is
	* output in improper 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(final Fraction fraction,
	final StringBuffer toAppendTo, final FieldPosition pos) {

	pos.setBeginIndex(0);
	pos.setEndIndex(0);

	getNumeratorFormat().format(fraction.getNumerator(), toAppendTo, pos);
	toAppendTo.append(" / ");
	getDenominatorFormat().format(fraction.getDenominator(), toAppendTo,
	pos);

	return toAppendTo;
	}

	/**
	* Formats an object and appends the result to a StringBuffer. <code>obj</code> must be either a
	* {@link Fraction} object or a {@link Number} object. Any other type of
	* object will result in an {@link IllegalArgumentException} being thrown.
	*
	* @param obj 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.
	* @see java.text.Format#format(java.lang.Object, java.lang.StringBuffer, java.text.FieldPosition)
	* @throws IllegalArgumentException is <code>obj</code> is not a valid type.
	*/
	@Override
	public StringBuffer format(final Object obj,
	final StringBuffer toAppendTo, final FieldPosition pos) {
	StringBuffer ret = null;

	if (obj instanceof Fraction) {
	ret = format((Fraction) obj, toAppendTo, pos);
	} else if (obj instanceof Number) {
	try {
	ret = format(new Fraction(((Number) obj).doubleValue()),
	toAppendTo, pos);
	} catch (ConvergenceException ex) {
	throw MathRuntimeException.createIllegalArgumentException(
	LocalizedFormats.CANNOT_CONVERT_OBJECT_TO_FRACTION,
	ex.getLocalizedMessage());
	}
	} else {
	throw MathRuntimeException.createIllegalArgumentException(
	LocalizedFormats.CANNOT_FORMAT_OBJECT_TO_FRACTION);
	}

	return ret;
	}

	/**
	* Parses a string to produce a {@link Fraction} object.
	* @param source the string to parse
	* @return the parsed {@link Fraction} object.
	* @exception ParseException if the beginning of the specified string
	* cannot be parsed.
	*/
	@Override
	public Fraction parse(final String source) throws ParseException {
	final ParsePosition parsePosition = new ParsePosition(0);
	final Fraction result = parse(source, parsePosition);
	if (parsePosition.getIndex() == 0) {
	throw MathRuntimeException.createParseException(
	parsePosition.getErrorIndex(),
	LocalizedFormats.UNPARSEABLE_FRACTION_NUMBER, source);
	}
	return result;
	}

	/**
	* Parses a string to produce a {@link Fraction} object. This method
	* expects the string to be formatted as an improper fraction.
	* @param source the string to parse
	* @param pos input/ouput parsing parameter.
	* @return the parsed {@link Fraction} object.
	*/
	@Override
	public Fraction parse(final String source, final ParsePosition pos) {
	final int initialIndex = pos.getIndex();

	// parse whitespace
	parseAndIgnoreWhitespace(source, pos);

	// parse numerator
	final 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 '/'
	final int startIndex = pos.getIndex();
	final 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
	final 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;
	}

	return new Fraction(num.intValue(), den.intValue());
	}

	}