Class ChoiceFormat
- java.lang.Object
-
- java.text.Format
-
- java.text.NumberFormat
-
- java.text.ChoiceFormat
- All Implemented Interfaces:
-
Serializable
,Cloneable
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. 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:
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)); }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)); }
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.
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.
- Since:
- 1.1
- See Also:
-
DecimalFormat
,MessageFormat
, Serialized Form
Nested Class Summary
Nested classes/interfaces declared in class java.text.NumberFormat
NumberFormat.Field
Field Summary
Fields declared in class java.text.NumberFormat
FRACTION_FIELD, INTEGER_FIELD
Constructor Summary
Constructor | Description |
---|---|
ChoiceFormat(double[] limits,
String[] formats) | Constructs with the limits and the corresponding formats. |
ChoiceFormat(String newPattern) | Constructs with limits and corresponding formats based on the pattern. |
Method Summary
Modifier and Type | Method | Description |
---|---|---|
void | applyPattern(String newPattern) | Sets the pattern. |
Object | clone() | Overrides Cloneable |
boolean | equals(Object obj) | Equality comparison between two |
StringBuffer | format(double number,
StringBuffer toAppendTo,
FieldPosition status) | Returns pattern with formatted double. |
StringBuffer | format(long number,
StringBuffer toAppendTo,
FieldPosition status) | Specialization of format. |
Object[] | getFormats() | Get the formats passed in the constructor. |
double[] | getLimits() | Get the limits passed in the constructor. |
int | hashCode() | Generates a hash code for the message format object. |
static double | nextDouble(double d) | Finds the least double greater than |
static double | nextDouble(double d,
boolean positive) | Finds the least double greater than |
Number | parse(String text,
ParsePosition status) | Parses a Number from the input text. |
static double | previousDouble(double d) | Finds the greatest double less than |
void | setChoices(double[] limits,
String[] formats) | Set the choices to be used in formatting. |
String | toPattern() | Gets the pattern. |
Methods declared in class java.text.NumberFormat
format, format, format, getAvailableLocales, getCurrency, getCurrencyInstance, getCurrencyInstance, getInstance, getInstance, getIntegerInstance, getIntegerInstance, getMaximumFractionDigits, getMaximumIntegerDigits, getMinimumFractionDigits, getMinimumIntegerDigits, getNumberInstance, getNumberInstance, getPercentInstance, getPercentInstance, getRoundingMode, isGroupingUsed, isParseIntegerOnly, parse, parseObject, setCurrency, setGroupingUsed, setMaximumFractionDigits, setMaximumIntegerDigits, setMinimumFractionDigits, setMinimumIntegerDigits, setParseIntegerOnly, setRoundingMode
Methods declared in class java.text.Format
format, formatToCharacterIterator, parseObject
Methods declared in class java.lang.Object
finalize, getClass, notify, notifyAll, toString, wait, wait, wait
Constructor Detail
ChoiceFormat
public ChoiceFormat(String newPattern)
Constructs with limits and corresponding formats based on the pattern.
- Parameters:
-
newPattern
- the new pattern string - Throws:
-
NullPointerException
- ifnewPattern
isnull
- See Also:
applyPattern(java.lang.String)
ChoiceFormat
public ChoiceFormat(double[] limits, String[] formats)
Constructs with the limits and the corresponding formats.
- Parameters:
-
limits
- limits in ascending order -
formats
- corresponding format strings - Throws:
-
NullPointerException
- iflimits
orformats
isnull
- See Also:
setChoices(double[], java.lang.String[])
Method Detail
applyPattern
public void applyPattern(String newPattern)
Sets the pattern.
- Parameters:
-
newPattern
- See the class description. - Throws:
-
NullPointerException
- ifnewPattern
isnull
toPattern
public String toPattern()
Gets the pattern.
- Returns:
- the pattern string
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]. 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. - Throws:
-
NullPointerException
- iflimits
orformats
isnull
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.
- Specified by:
-
format
in classNumberFormat
- Parameters:
-
number
- the long number to format -
toAppendTo
- the StringBuffer to which the formatted text is to be appended -
status
- keeps track on the position of the field within the returned string. For example, for formatting a number123456789
inLocale.US
locale, if the givenfieldPosition
isNumberFormat.INTEGER_FIELD
, the begin index and end index offieldPosition
will be set to 0 and 11, respectively for the output string123,456,789
. - Returns:
- the formatted StringBuffer
- See Also:
Format.format(java.lang.Object)
format
public StringBuffer format(double number, StringBuffer toAppendTo, FieldPosition status)
Returns pattern with formatted double.
- Specified by:
-
format
in classNumberFormat
- Parameters:
-
number
- number to be formatted and substituted. -
toAppendTo
- where text is appended. -
status
- ignore no useful status is returned. - Returns:
- the formatted StringBuffer
- Throws:
-
NullPointerException
- iftoAppendTo
isnull
- See Also:
Format.format(java.lang.Object)
parse
public Number parse(String text, ParsePosition status)
Parses a Number from the input text.
- Specified by:
-
parse
in classNumberFormat
- Parameters:
-
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. - Returns:
- A Number representing the value of the number parsed.
- Throws:
-
NullPointerException
- ifstatus
isnull
or iftext
isnull
and the list of choice strings is not empty. - See Also:
-
NumberFormat.isParseIntegerOnly()
,Format.parseObject(java.lang.String, java.text.ParsePosition)
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.
- Parameters:
-
d
- the reference value - Returns:
- the least double value greather than
d
- See Also:
previousDouble(double)
previousDouble
public static final double previousDouble(double d)
Finds the greatest double less than d
. If NaN
, returns same value.
- Parameters:
-
d
- the reference value - Returns:
- the greatest double value less than
d
- See Also:
nextDouble(double)
clone
public Object clone()
Overrides Cloneable
- Overrides:
-
clone
in classNumberFormat
- Returns:
- a clone of this instance.
- See Also:
Cloneable
hashCode
public int hashCode()
Generates a hash code for the message format object.
- Overrides:
-
hashCode
in classNumberFormat
- Returns:
- a hash code value for this object.
- See Also:
-
Object.equals(java.lang.Object)
,System.identityHashCode(java.lang.Object)
equals
public boolean equals(Object obj)
Equality comparison between two
- Overrides:
-
equals
in classNumberFormat
- Parameters:
-
obj
- the reference object with which to compare. - Returns:
-
true
if this object is the same as the obj argument;false
otherwise. - See Also:
-
Object.hashCode()
,HashMap
nextDouble
public static double nextDouble(double d, boolean positive)
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. Does not affect floating-point flags, provided these member functions do not: Double.longBitsToDouble(long) Double.doubleToLongBits(double) Double.isNaN(double)
- Parameters:
-
d
- the reference value -
positive
-true
if the least double is desired;false
otherwise - Returns:
- the least or greater double value