Class DecoratedChoiceFormat

  extended by java.text.Format
      extended by net.sf.fikin.pojostate.format.DecoratedChoiceFormat
All Implemented Interfaces:, java.lang.Cloneable

public class DecoratedChoiceFormat
extends java.text.Format

Decorate java.text.ChoiceFormat with ability to accept null values, returning empty string for them. A ChoiceFormat allows you to attach a format to a range of numbers. It is generally used in a MessageFormat 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:

 X matches j if and only if limit[j] <= X < limit[j+1]
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 \u221E as equivalent to infinity(INF).

Note: ChoiceFormat differs from the other Format classes in that you create a ChoiceFormat object with a constructor (not with a getInstance style factory method). The factory methods aren't necessary because ChoiceFormat doesn't require any complex setup for a given locale. In fact, ChoiceFormat doesn't implement any locale specific behavior.

When creating a ChoiceFormat, you must specify an array of formats and an array of limits. The length of these arrays must be the same. For example,

Here is a simple example that shows formatting and parsing:

 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 <= 8.0; ++i) {
     System.out.println(i + " -> " + form.format(i) + " -> "
                              + form.parse(form.format(i),status));
Here is a more complex example, with a pattern format:
 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}");
 Object[] testArgs = {null, "ADisk", null};
 for (int i = 0; i < 4; ++i) {
     testArgs[0] = new Integer(i);
     testArgs[2] = testArgs[0];

Specifying a pattern for ChoiceFormat objects is fairly straightforward. For example:

 ChoiceFormat fmt = new ChoiceFormat(
      "-1#is negative| 0#is zero or fraction | 1#is one |1.0<is 1+ |2#is two |2<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));
And the output result would be like the following:
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.


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. created on Jul 20, 2005

$Revision: 1.2 $
See Also:
Serialized Form

Nested Class Summary
Nested classes/interfaces inherited from class java.text.Format
Constructor Summary
DecoratedChoiceFormat(double[] limits, java.lang.String[] formats)
          Constructs with the limits and the corresponding formats.
DecoratedChoiceFormat(java.lang.String applyPattern)
          Constructs with limits and corresponding formats based on the pattern.
Method Summary
 java.lang.StringBuffer format(java.lang.Object obj, java.lang.StringBuffer toAppendTo, java.text.FieldPosition status)
          Returns pattern with formatted double.
 java.lang.Object parseObject(java.lang.String text, java.text.ParsePosition status)
          Parses a Number from the input text.
Methods inherited from class java.text.Format
clone, format, formatToCharacterIterator, parseObject
Methods inherited from class java.lang.Object
equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail


public DecoratedChoiceFormat(java.lang.String applyPattern)
Constructs with limits and corresponding formats based on the pattern.

applyPattern - See the class description.
See Also:


public DecoratedChoiceFormat(double[] limits,
                             java.lang.String[] formats)
Constructs with the limits and the corresponding formats.

limits - contains the top value that you want parsed with that format,and should be in ascending sorted order. When formatting X, the choice will be the i, where limit[i] <= X < limit[i+1]. If the limit array is not in ascending order, the results of formatting will be incorrect.
formats - are the formats you want to use for each limit. They can be either Format objects or Strings. When formatting with object Y, if the object is a NumberFormat, then ((NumberFormat) Y).format(X) is called. Otherwise Y.toString() is called.
See Also:
ChoiceFormat.setChoices(double[], java.lang.String[])
Method Detail


public java.lang.StringBuffer format(java.lang.Object obj,
                                     java.lang.StringBuffer toAppendTo,
                                     java.text.FieldPosition status)
Returns pattern with formatted double.

Specified by:
format in class java.text.Format
obj - is lava.lang.Number to be formatted & substituted.
toAppendTo - where text is appended.
status - ignore no useful status is returned.


public java.lang.Object parseObject(java.lang.String text,
                                    java.text.ParsePosition status)
Parses a Number from the input text.

Specified by:
parseObject in class java.text.Format
text - the source text.
status - an input-output parameter. On input, the status.index field indicates the first character of the source text that should be parsed. On exit, if no error occurred, status.index is set to the first unparsed character in the source text. On exit, if an error did occur, status.index is unchanged and status.errorIndex is set to the first index of the character that caused the parse to fail.
A Number representing the value of the number parsed.

Copyright © 2005 Nikolay Fiykov. All Rights Reserved.