choiceformat.java

java源代码 请看看啊 提点宝贵的意见

/*
 * @(#)ChoiceFormat.java	1.32 03/01/23
 *
 * Copyright 2003 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

/*
 * (C) Copyright Taligent, Inc. 1996, 1997 - All Rights Reserved
 * (C) Copyright IBM Corp. 1996 - 1998 - All Rights Reserved
 *
 *   The original version of this source code and documentation is copyrighted
 * and owned by Taligent, Inc., a wholly-owned subsidiary of IBM. These
 * materials are provided under terms of a License Agreement between Taligent
 * and Sun. This technology is protected by multiple US and International
 * patents. This notice and attribution to Taligent may not be removed.
 *   Taligent is a registered trademark of Taligent, Inc.
 *
 */

package java.text;

import java.io.InvalidObjectException;
import java.io.IOException;
import java.io.ObjectInputStream;
import sun.text.Utility;

/**
 * A <code>ChoiceFormat</code> allows you to attach a format to a range of numbers.
 * It is generally used in a <code>MessageFormat</code> for handling plurals.
 * The choice is specified with an ascending list of doubles, where each item
 * specifies a half-open interval up to the next item:
 * <blockquote>
 * <pre>
 * X matches j if and only if limit[j] &lt;= X &lt; limit[j+1]
 * </pre>
 * </blockquote>
 * If there is no match, then either the first or last index is used, depending
 * on whether the number (X) is too low or too high.  If the limit array is not
 * in ascending order, the results of formatting will be incorrect.  ChoiceFormat
 * also accepts <code>&#92;u221E</code> as equivalent to infinity(INF).
 *
 * <p>
 * <strong>Note:</strong>
 * <code>ChoiceFormat</code> differs from the other <code>Format</code>
 * classes in that you create a <code>ChoiceFormat</code> object with a
 * constructor (not with a <code>getInstance</code> style factory
 * method). The factory methods aren't necessary because <code>ChoiceFormat</code>
 * doesn't require any complex setup for a given locale. In fact,
 * <code>ChoiceFormat</code> doesn't implement any locale specific behavior.
 *
 * <p>
 * When creating a <code>ChoiceFormat</code>, you must specify an array of formats
 * and an array of limits. The length of these arrays must be the same.
 * For example,
 * <ul>
 * <li>
 *     <em>limits</em> = {1,2,3,4,5,6,7}<br>
 *     <em>formats</em> = {"Sun","Mon","Tue","Wed","Thur","Fri","Sat"}
 * <li>
 *     <em>limits</em> = {0, 1, ChoiceFormat.nextDouble(1)}<br>
 *     <em>formats</em> = {"no files", "one file", "many files"}<br>
 *     (<code>nextDouble</code> can be used to get the next higher double, to
 *     make the half-open interval.)
 * </ul>
 *
 * <p>
 * Here is a simple example that shows formatting and parsing:
 * <blockquote>
 * <pre>
 * double[] limits = {1,2,3,4,5,6,7};
 * String[] monthNames = {"Sun","Mon","Tue","Wed","Thur","Fri","Sat"};
 * ChoiceFormat form = new ChoiceFormat(limits, monthNames);
 * ParsePosition status = new ParsePosition(0);
 * for (double i = 0.0; i &lt;= 8.0; ++i) {
 *     status.setIndex(0);
 *     System.out.println(i + " -&gt; " + form.format(i) + " -&gt; "
 *                              + form.parse(form.format(i),status));
 * }
 * </pre>
 * </blockquote>
 * Here is a more complex example, with a pattern format:
 * <blockquote>
 * <pre>
 * double[] filelimits = {0,1,2};
 * String[] filepart = {"are no files","is one file","are {2} files"};
 * ChoiceFormat fileform = new ChoiceFormat(filelimits, filepart);
 * Format[] testFormats = {fileform, null, NumberFormat.getInstance()};
 * MessageFormat pattform = new MessageFormat("There {0} on {1}");
 * pattform.setFormats(testFormats);
 * Object[] testArgs = {null, "ADisk", null};
 * for (int i = 0; i &lt; 4; ++i) {
 *     testArgs[0] = new Integer(i);
 *     testArgs[2] = testArgs[0];
 *     System.out.println(pattform.format(testArgs));
 * }
 * </pre>
 * </blockquote>
 * <p>
 * Specifying a pattern for ChoiceFormat objects is fairly straightforward.
 * For example:
 * <blockquote>
 * <pre>
 * ChoiceFormat fmt = new ChoiceFormat(
 *      "-1#is negative| 0#is zero or fraction | 1#is one |1.0&lt;is 1+ |2#is two |2&lt;is more than 2.");
 * System.out.println("Formatter Pattern : " + fmt.toPattern());
 *
 * System.out.println("Format with -INF : " + fmt.format(Double.NEGATIVE_INFINITY));
 * System.out.println("Format with -1.0 : " + fmt.format(-1.0));
 * System.out.println("Format with 0 : " + fmt.format(0));
 * System.out.println("Format with 0.9 : " + fmt.format(0.9));
 * System.out.println("Format with 1.0 : " + fmt.format(1));
 * System.out.println("Format with 1.5 : " + fmt.format(1.5));
 * System.out.println("Format with 2 : " + fmt.format(2));
 * System.out.println("Format with 2.1 : " + fmt.format(2.1));
 * System.out.println("Format with NaN : " + fmt.format(Double.NaN));
 * System.out.println("Format with +INF : " + fmt.format(Double.POSITIVE_INFINITY));
 * </pre>
 * </blockquote>
 * And the output result would be like the following:
 * <pre>
 * <blockquote>
 *   Format with -INF : is negative
 *   Format with -1.0 : is negative
 *   Format with 0 : is zero or fraction
 *   Format with 0.9 : is zero or fraction
 *   Format with 1.0 : is one
 *   Format with 1.5 : is 1+
 *   Format with 2 : is two
 *   Format with 2.1 : is more than 2.
 *   Format with NaN : is negative
 *   Format with +INF : is more than 2.
 * </pre>
 * </blockquote>
 *
 * <h4><a name="synchronization">Synchronization</a></h4>
 *
 * <p>
 * Choice formats are not synchronized.
 * It is recommended to create separate format instances for each thread.
 * If multiple threads access a format concurrently, it must be synchronized
 * externally.
 *
 *
 * @see          DecimalFormat
 * @see          MessageFormat
 * @version      1.22 09/21/98
 * @author       Mark Davis
 */
public class ChoiceFormat extends NumberFormat {

    /**
     * Sets the pattern.
     * @param newPattern See the class description.
     */
    public void applyPattern(String newPattern) {
        StringBuffer[] segments = new StringBuffer[2];
        for (int i = 0; i < segments.length; ++i) {
            segments[i] = new StringBuffer();
        }
        double[] newChoiceLimits = new double[30];
        String[] newChoiceFormats = new String[30];
        int count = 0;
        int part = 0;
        double startValue = 0;
        double oldStartValue = Double.NaN;
        boolean inQuote = false;
        for (int i = 0; i < newPattern.length(); ++i) {
            char ch = newPattern.charAt(i);
            if (ch=='\'') {
                // Check for "''" indicating a literal quote
                if ((i+1)<newPattern.length() && newPattern.charAt(i+1)==ch) {
                    segments[part].append(ch);
                    ++i;
                } else {
                    inQuote = !inQuote;
                }
            } else if (inQuote) {
                segments[part].append(ch);
            } else if (ch == '<' || ch == '#' || ch == '\u2264') {
                if (segments[0].equals("")) {
                    throw new IllegalArgumentException();
                }
                try {
                    String tempBuffer = segments[0].toString();
                    if (tempBuffer.equals("\u221E")) {
                        startValue = Double.POSITIVE_INFINITY;
                    } else if (tempBuffer.equals("-\u221E")) {
                        startValue = Double.NEGATIVE_INFINITY;
                    } else {
                        startValue = Double.valueOf(segments[0].toString()).doubleValue();
                    }
                } catch (Exception e) {
                    throw new IllegalArgumentException();
                }
                if (ch == '<' && startValue != Double.POSITIVE_INFINITY &&
                        startValue != Double.NEGATIVE_INFINITY) {
                    startValue = nextDouble(startValue);
                }
                if (startValue <= oldStartValue) {
                    throw new IllegalArgumentException();
                }
                segments[0].setLength(0);
                part = 1;
            } else if (ch == '|') {
                if (count == newChoiceLimits.length) {
                    newChoiceLimits = doubleArraySize(newChoiceLimits);
                    newChoiceFormats = doubleArraySize(newChoiceFormats);
                }
                newChoiceLimits[count] = startValue;
                newChoiceFormats[count] = segments[1].toString();
                ++count;
                oldStartValue = startValue;
                segments[1].setLength(0);
                part = 0;
            } else {
                segments[part].append(ch);
            }
        }
        // clean up last one
        if (part == 1) {
            if (count == newChoiceLimits.length) {
                newChoiceLimits = doubleArraySize(newChoiceLimits);
                newChoiceFormats = doubleArraySize(newChoiceFormats);
            }
            newChoiceLimits[count] = startValue;
            newChoiceFormats[count] = segments[1].toString();
            ++count;
        }
        choiceLimits = new double[count];
        System.arraycopy(newChoiceLimits, 0, choiceLimits, 0, count);
        choiceFormats = new String[count];
        System.arraycopy(newChoiceFormats, 0, choiceFormats, 0, count);
    }

    /**
     * Gets the pattern.
     */
    public String toPattern() {
        StringBuffer result = new StringBuffer();
        for (int i = 0; i < choiceLimits.length; ++i) {
            if (i != 0) {
                result.append('|');
            }
            // choose based upon which has less precision
            // approximate that by choosing the closest one to an integer.
            // could do better, but it's not worth it.
            double less = previousDouble(choiceLimits[i]);
            double tryLessOrEqual = Math.abs(Math.IEEEremainder(choiceLimits[i], 1.0d));
            double tryLess = Math.abs(Math.IEEEremainder(less, 1.0d));

            if (tryLessOrEqual < tryLess) {
                result.append(""+choiceLimits[i]);
                result.append('#');
            } else {
                if (choiceLimits[i] == Double.POSITIVE_INFINITY) {
                    result.append("\u221E");
                } else if (choiceLimits[i] == Double.NEGATIVE_INFINITY) {
                    result.append("-\u221E");
                } else {
                    result.append(""+less);
                }
                result.append('<');
            }
            // Append choiceFormats[i], using quotes if there are special characters.
            // Single quotes themselves must be escaped in either case.
            String text = choiceFormats[i];
            boolean needQuote = text.indexOf('<') >= 0
                || text.indexOf('#') >= 0
                || text.indexOf('\u2264') >= 0
                || text.indexOf('|') >= 0;
            if (needQuote) result.append('\'');
            if (text.indexOf('\'') < 0) result.append(text);
            else {
                for (int j=0; j<text.length(); ++j) {
                    char c = text.charAt(j);
                    result.append(c);
                    if (c == '\'') result.append(c);
                }
            }
            if (needQuote) result.append('\'');
        }
        return result.toString();
    }

    /**
     * Constructs with limits and corresponding formats based on the pattern.
     * @see #applyPattern
     */
    public ChoiceFormat(String newPattern)  {
        applyPattern(newPattern);
    }

    /**
     * Constructs with the limits and the corresponding formats.
     * @see #setChoices
     */
    public ChoiceFormat(double[] limits, String[] formats) {
        setChoices(limits, formats);
    }