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# Class java.text.ChoiceFormat

    java.lang.Object
       |
       +----java.text.Format
               |
               +----java.text.NumberFormat
                       |
                       +----java.text.ChoiceFormat

public class ChoiceFormat
extends NumberFormat

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.

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,

- limits = {1,2,3,4,5,6,7}
  formats = {"Sun","Mon","Tue","Wed","Thur","Fri","Sat"} limits = {0, 1, ChoiceFormat.nextDouble(1)}
  formats = {"no files", "one file", "many files"}
  (`nextDouble` can be used to get the next higher double, to make the half-open interval.)

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) {
>          status.setIndex(0);
>          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}");
>      pattform.setFormats(testFormats);
>      Object[] testArgs = {null, "ADisk", null};
>      for (int i = 0; i < 4; ++i) {
>          testArgs[0] = new Integer(i);
>          testArgs[2] = testArgs[0];
>          System.out.println(pattform.format(testArgs));
>      }

See Also:
  DecimalFormat, MessageFormat

##

ChoiceFormat(double[], String[])
  Constructs with the limits and the corresponding formats.
ChoiceFormat(String)
  Constructs with limits and corresponding formats based on the pattern.

##

applyPattern(String)
  Sets the pattern.
clone()
  Overrides Cloneable
equals(Object)
  Equality comparision between two
format(double, StringBuffer, FieldPosition)
  Specialization of format.
format(long, StringBuffer, FieldPosition)
  Specialization of format.
getFormats()
  Get the formats passed in the constructor.
getLimits()
  Get the limits passed in the constructor.
hashCode()
  Generates a hash code for the message format object.
nextDouble(double)
  Finds the least double greater than d.
nextDouble(double, boolean)
parse(String, ParsePosition)
  Returns a Long if possible (e.g.
previousDouble(double)
  Finds the greatest double less than d.
setChoices(double[], String[])
  Set the choices to be used in formatting.
toPattern()
  Gets the pattern.

##

ChoiceFormat

     public ChoiceFormat(String newPattern)

  Constructs with limits and corresponding formats based on the pattern.

ChoiceFormat

     public ChoiceFormat(double limits[],
                         String formats[])

  Constructs with the limits and the corresponding formats.

  See Also:
    setChoices

##

applyPattern

     public void applyPattern(String newPattern)

  Sets the pattern.

  Parameters:
    newPattern - See the class description.

toPattern

     public String toPattern()

  Gets the pattern.

setChoices

     public void setChoices(double limits[],
                            String formats[])

  Set the choices to be used in formatting.

  Parameters:
    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].
    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.

getLimits

     public double[] getLimits()

  Get the limits passed in the constructor.

  Returns:
    the limits.

getFormats

     public Object[] getFormats()

  Get the formats passed in the constructor.

  Returns:
    the formats.

format

     public StringBuffer format(long number,
                                StringBuffer toAppendTo,
                                FieldPosition status)

  Specialization of format. This method really calls `format(double, StringBuffer, FieldPosition)` thus the range of longs that are supported is only equal to the range that can be stored by double. This will never be a practical limitation.

  Overrides:
    format in class NumberFormat

format

     public StringBuffer format(double number,
                                StringBuffer toAppendTo,
                                FieldPosition status)

  Specialization of format.

  Overrides:
    format in class NumberFormat

parse

     public Number parse(String text,
                         ParsePosition status)

  Returns a Long if possible (e.g.

  Overrides:
    parse in class NumberFormat

nextDouble

     public static final double nextDouble(double d)

  Finds the least double greater than d. If NaN, returns same value.

  Used to make half-open intervals.

  See Also:
    previousDouble

previousDouble

     public static final double previousDouble(double d)

  Finds the greatest double less than d. If NaN, returns same value.

  See Also:
    nextDouble

clone

     public Object clone()

  Overrides Cloneable

  Overrides:
    clone in class NumberFormat

hashCode

     public int hashCode()

  Generates a hash code for the message format object.

  Overrides:
    hashCode in class NumberFormat

equals

     public boolean equals(Object obj)

  Equality comparision between two

  Overrides:
    equals in class NumberFormat

nextDouble

     public static double nextDouble(double d,
                                     boolean positive)

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