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Java example source code file (AbstractFormat.java)

This example Java source code file (AbstractFormat.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

abstractformat, fieldposition, locale, numberformat, override, parseposition, serializable, string, stringbuffer, text, util

The AbstractFormat.java Java example source code

/*
 * 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.math3.fraction;

import java.io.Serializable;
import java.text.FieldPosition;
import java.text.NumberFormat;
import java.text.ParsePosition;
import java.util.Locale;

import org.apache.commons.math3.exception.NullArgumentException;
import org.apache.commons.math3.exception.util.LocalizedFormats;

/**
 * Common part shared by both {@link FractionFormat} and {@link BigFractionFormat}.
 * @since 2.0
 */
public abstract class AbstractFormat extends NumberFormat implements Serializable {

    /** Serializable version identifier. */
    private static final long serialVersionUID = -6981118387974191891L;

    /** The format used for the denominator. */
    private NumberFormat denominatorFormat;

    /** The format used for the numerator. */
    private NumberFormat numeratorFormat;

    /**
     * Create an improper formatting instance with the default number format
     * for the numerator and denominator.
     */
    protected AbstractFormat() {
        this(getDefaultNumberFormat());
    }

    /**
     * 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.
     */
    protected AbstractFormat(final NumberFormat format) {
        this(format, (NumberFormat) format.clone());
    }

    /**
     * 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.
     */
    protected AbstractFormat(final NumberFormat numeratorFormat,
                             final NumberFormat denominatorFormat) {
        this.numeratorFormat   = numeratorFormat;
        this.denominatorFormat = denominatorFormat;
    }

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

    /**
     * Create a default number format.  The default number format is based on
     * {@link NumberFormat#getNumberInstance(java.util.Locale)}. The only
     * customization is the maximum number of BigFraction digits, which is set to 0.
     * @param locale the specific locale used by the format.
     * @return the default number format specific to the given locale.
     */
    protected static NumberFormat getDefaultNumberFormat(final Locale locale) {
        final NumberFormat nf = NumberFormat.getNumberInstance(locale);
        nf.setMaximumFractionDigits(0);
        nf.setParseIntegerOnly(true);
        return nf;
    }

    /**
     * Access the denominator format.
     * @return the denominator format.
     */
    public NumberFormat getDenominatorFormat() {
        return denominatorFormat;
    }

    /**
     * Access the numerator format.
     * @return the numerator format.
     */
    public NumberFormat getNumeratorFormat() {
        return numeratorFormat;
    }

    /**
     * Modify the denominator format.
     * @param format the new denominator format value.
     * @throws NullArgumentException if {@code format} is {@code null}.
     */
    public void setDenominatorFormat(final NumberFormat format) {
        if (format == null) {
            throw new NullArgumentException(LocalizedFormats.DENOMINATOR_FORMAT);
        }
        this.denominatorFormat = format;
    }

    /**
     * Modify the numerator format.
     * @param format the new numerator format value.
     * @throws NullArgumentException if {@code format} is {@code null}.
     */
    public void setNumeratorFormat(final NumberFormat format) {
        if (format == null) {
            throw new NullArgumentException(LocalizedFormats.NUMERATOR_FORMAT);
        }
        this.numeratorFormat = format;
    }

    /**
     * Parses <code>source until a non-whitespace character is found.
     * @param source the string to parse
     * @param pos input/output parsing parameter.  On output, <code>pos
     *        holds the index of the next non-whitespace character.
     */
    protected static void parseAndIgnoreWhitespace(final String source,
                                                   final ParsePosition pos) {
        parseNextCharacter(source, pos);
        pos.setIndex(pos.getIndex() - 1);
    }

    /**
     * Parses <code>source until a non-whitespace character is found.
     * @param source the string to parse
     * @param pos input/output parsing parameter.
     * @return the first non-whitespace character.
     */
    protected static char parseNextCharacter(final String source,
                                             final ParsePosition pos) {
         int index = pos.getIndex();
         final int n = source.length();
         char ret = 0;

         if (index < n) {
             char c;
             do {
                 c = source.charAt(index++);
             } while (Character.isWhitespace(c) && index < n);
             pos.setIndex(index);

             if (index < n) {
                 ret = c;
             }
         }

         return ret;
    }

    /**
     * Formats a double value as a fraction and appends the result to a StringBuffer.
     *
     * @param value the double value to format
     * @param buffer StringBuffer to append to
     * @param position On input: an alignment field, if desired. On output: the
     *            offsets of the alignment field
     * @return a reference to the appended buffer
     * @see #format(Object, StringBuffer, FieldPosition)
     */
    @Override
    public StringBuffer format(final double value,
                               final StringBuffer buffer, final FieldPosition position) {
        return format(Double.valueOf(value), buffer, position);
    }


    /**
     * Formats a long value as a fraction and appends the result to a StringBuffer.
     *
     * @param value the long value to format
     * @param buffer StringBuffer to append to
     * @param position On input: an alignment field, if desired. On output: the
     *            offsets of the alignment field
     * @return a reference to the appended buffer
     * @see #format(Object, StringBuffer, FieldPosition)
     */
    @Override
    public StringBuffer format(final long value,
                               final StringBuffer buffer, final FieldPosition position) {
        return format(Long.valueOf(value), buffer, position);
    }

}

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