java.lang.Object | |||
↳ | java.text.Format | ||
↳ | java.text.NumberFormat | ||
↳ | java.text.ChoiceFormat |
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:
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 acceptsX matches j if and only if limit[j] <= X < limit[j+1]
\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,
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:
Here is a more complex example, with a pattern format:double[] limits = {1,2,3,4,5,6,7}; String[] dayOfWeekNames = {"Sun","Mon","Tue","Wed","Thur","Fri","Sat"}; ChoiceFormat form = new ChoiceFormat(limits, dayOfWeekNames); 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)); }
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)); }
Specifying a pattern for ChoiceFormat objects is fairly straightforward. For example:
And the output result would be like the following: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));
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.
[Expand]
Inherited Constants | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
From class
java.text.NumberFormat
|
Public Constructors | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Constructs with limits and corresponding formats based on the pattern.
| |||||||||||
Constructs with the limits and the corresponding formats.
|
Public Methods | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Sets the pattern.
| |||||||||||
Overrides Cloneable
| |||||||||||
Equality comparision between two
| |||||||||||
Specialization of format.
| |||||||||||
Returns pattern with formatted double.
| |||||||||||
Get the formats passed in the constructor.
| |||||||||||
Get the limits passed in the constructor.
| |||||||||||
Generates a hash code for the message format object.
| |||||||||||
Finds the least double greater than d (if positive == true),
or the greatest double less than d (if positive == false).
| |||||||||||
Finds the least double greater than d.
| |||||||||||
Parses a Number from the input text.
| |||||||||||
Finds the greatest double less than d.
| |||||||||||
Set the choices to be used in formatting.
| |||||||||||
Gets the pattern.
|
[Expand]
Inherited Methods | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
From class
java.text.NumberFormat
| |||||||||||
From class
java.text.Format
| |||||||||||
From class
java.lang.Object
|
Constructs with limits and corresponding formats based on the pattern.
Constructs with the limits and the corresponding formats.
Sets the pattern.
newPattern | See the class description. |
---|
Equality comparision between two
obj | the reference object with which to compare. |
---|
true
if this object is the same as the obj
argument; false
otherwise.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.
Returns pattern with formatted double.
number | number to be formatted & substituted. |
---|---|
toAppendTo | where text is appended. |
status | ignore no useful status is returned. |
Get the limits passed in the constructor.
Generates a hash code for the message format object.
Finds the least double greater than d (if positive == true), or the greatest double less than d (if positive == false). If NaN, returns same value. Does not affect floating-point flags, provided these member functions do not: Double.longBitsToDouble(long) Double.doubleToLongBits(double) Double.isNaN(double)
Finds the least double greater than d. If NaN, returns same value.
Used to make half-open intervals.
Parses a Number from the input text.
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 occured, 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. |
Finds the greatest double less than d. If NaN, returns same value.
Set the choices to be used in formatting.
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. |