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
*/
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 NullArgumentException if {@code format} is {@code null}.
*/
public void setWholeFormat(final NumberFormat format) {
if (format == null) {
throw new NullArgumentException(LocalizedFormats.WHOLE_FORMAT);
}
this.wholeFormat = format;
}
}