ChoiceFormat
open class ChoiceFormat : NumberFormat
kotlin.Any | |||
↳ | 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:
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,
- 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:
<code>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)); } </code>Here is a more complex example, with a pattern format:
<code>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)); } </code>
Specifying a pattern for ChoiceFormat objects is fairly straightforward. For example:
<code>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)); </code>And the output result would be like the following:
<code>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. </code>
Synchronization
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.
Summary
Inherited constants | |
---|---|
Public constructors | |
---|---|
ChoiceFormat(newPattern: String!) Constructs with limits and corresponding formats based on the pattern. |
|
ChoiceFormat(limits: DoubleArray!, formats: Array<String!>!) Constructs with the limits and the corresponding formats. |
Public methods | |
---|---|
open Unit |
applyPattern(newPattern: String!) Sets the pattern. |
open Any |
clone() Overrides Cloneable |
open Boolean |
Equality comparison between two |
open StringBuffer |
format(number: Long, toAppendTo: StringBuffer, status: FieldPosition) Specialization of format. |
open StringBuffer |
format(number: Double, toAppendTo: StringBuffer, status: FieldPosition) Returns pattern with formatted double. |
open Array<Any!>! | |
open DoubleArray! | |
open Int |
hashCode() Generates a hash code for the message format object. |
static Double |
nextDouble(d: Double) Finds the least double greater than |
open static Double |
nextDouble(d: Double, positive: Boolean) Finds the least double greater than |
open Number? |
parse(text: String, status: ParsePosition) Parses a Number from the input text. |
static Double |
previousDouble(d: Double) Finds the greatest double less than |
open Unit |
setChoices(limits: DoubleArray!, formats: Array<String!>!) Set the choices to be used in formatting. |
open String! |
Gets the pattern. |
Inherited functions | |
---|---|
Public constructors
ChoiceFormat
ChoiceFormat(newPattern: String!)
Constructs with limits and corresponding formats based on the pattern.
Parameters | |
---|---|
newPattern |
String!: the new pattern string |
Exceptions | |
---|---|
java.lang.NullPointerException |
if newPattern is null |
See Also
ChoiceFormat
ChoiceFormat(
limits: DoubleArray!,
formats: Array<String!>!)
Constructs with the limits and the corresponding formats.
Parameters | |
---|---|
limits |
DoubleArray!: limits in ascending order |
formats |
Array<String!>!: corresponding format strings |
Exceptions | |
---|---|
java.lang.NullPointerException |
if limits or formats is null |
See Also
Public methods
applyPattern
open fun applyPattern(newPattern: String!): Unit
Sets the pattern.
Parameters | |
---|---|
newPattern |
String!: See the class description. |
Exceptions | |
---|---|
java.lang.NullPointerException |
if newPattern is null |
clone
open fun clone(): Any
Overrides Cloneable
Return | |
---|---|
Any |
a clone of this instance. |
Exceptions | |
---|---|
java.lang.CloneNotSupportedException |
if the object's class does not support the Cloneable interface. Subclasses that override the clone method can also throw this exception to indicate that an instance cannot be cloned. |
equals
open fun equals(other: Any?): Boolean
Equality comparison between two
Parameters | |
---|---|
obj |
the reference object with which to compare. |
Return | |
---|---|
Boolean |
true if this object is the same as the obj argument; false otherwise. |
format
open fun format(
number: Long,
toAppendTo: StringBuffer,
status: FieldPosition
): StringBuffer
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.
Parameters | |
---|---|
number |
Long: the long number to format |
toAppendTo |
StringBuffer: the StringBuffer to which the formatted text is to be appended |
pos |
keeps track on the position of the field within the returned string. For example, for formatting a number 123456789 in Locale.US locale, if the given fieldPosition is NumberFormat#INTEGER_FIELD , the begin index and end index of fieldPosition will be set to 0 and 11, respectively for the output string 123,456,789 . |
Return | |
---|---|
StringBuffer |
the formatted StringBuffer |
Exceptions | |
---|---|
java.lang.ArithmeticException |
if rounding is needed with rounding mode being set to RoundingMode.UNNECESSARY |
format
open fun format(
number: Double,
toAppendTo: StringBuffer,
status: FieldPosition
): StringBuffer
Returns pattern with formatted double.
Parameters | |
---|---|
number |
Double: number to be formatted and substituted. |
toAppendTo |
StringBuffer: where text is appended. |
pos |
keeps track on the position of the field within the returned string. For example, for formatting a number 1234567.89 in Locale.US locale, if the given fieldPosition is NumberFormat#INTEGER_FIELD , the begin index and end index of fieldPosition will be set to 0 and 9, respectively for the output string 1,234,567.89 . |
status |
FieldPosition: ignore no useful status is returned. |
Return | |
---|---|
StringBuffer |
the formatted StringBuffer |
Exceptions | |
---|---|
java.lang.ArithmeticException |
if rounding is needed with rounding mode being set to RoundingMode.UNNECESSARY |
java.lang.NullPointerException |
if toAppendTo is null |
getFormats
open fun getFormats(): Array<Any!>!
Return | |
---|---|
Array<Any!>! |
a copy of the String[] array supplied to the constructor or the most recent call to setChoices(double[],java.lang.String[]) . |
getLimits
open fun getLimits(): DoubleArray!
Return | |
---|---|
DoubleArray! |
a copy of the double[] array supplied to the constructor or the most recent call to setChoices(double[],java.lang.String[]) . |
hashCode
open fun hashCode(): Int
Generates a hash code for the message format object.
Return | |
---|---|
Int |
a hash code value for this object. |
nextDouble
static fun nextDouble(d: Double): Double
Finds the least double greater than d
. If NaN
, returns same value.
Used to make half-open intervals.
Parameters | |
---|---|
d |
Double: the reference value |
Return | |
---|---|
Double |
the least double value greather than d |
See Also
nextDouble
open static fun nextDouble(
d: Double,
positive: Boolean
): Double
Finds the least double greater than d
(if positive
is true
), or the greatest double less than d
(if positive
is false
). If NaN
, returns same value.
Parameters | |
---|---|
d |
Double: the reference value |
positive |
Boolean: true if the least double is desired; false otherwise |
Return | |
---|---|
Double |
the least or greater double value |
parse
open fun parse(
text: String,
status: ParsePosition
): Number?
Parses a Number from the input text.
Parameters | |
---|---|
source |
the String to parse |
parsePosition |
the parse position |
text |
String: the source text. |
status |
ParsePosition: 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. |
Return | |
---|---|
Number? |
A Number representing the value of the number parsed. |
Exceptions | |
---|---|
java.lang.NullPointerException |
if status is null or if text is null and the list of choice strings is not empty. |
previousDouble
static fun previousDouble(d: Double): Double
Finds the greatest double less than d
. If NaN
, returns same value.
Parameters | |
---|---|
d |
Double: the reference value |
Return | |
---|---|
Double |
the greatest double value less than d |
See Also
setChoices
open fun setChoices(
limits: DoubleArray!,
formats: Array<String!>!
): Unit
Set the choices to be used in formatting.
Parameters | |
---|---|
limits |
DoubleArray!: 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 |
Array<String!>!: 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. |
Exceptions | |
---|---|
java.lang.NullPointerException |
if limits or formats is null |
toPattern
open fun toPattern(): String!
Gets the pattern.
Return | |
---|---|
String! |
the pattern string |