- java.lang.Object
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- java.text.Format
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- java.text.NumberFormat
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- java.text.ChoiceFormat
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- All Implemented Interfaces:
- Serializable, Cloneable
public class ChoiceFormat extends NumberFormat
AChoiceFormat
allows you to attach a format to a range of numbers. It is generally used in aMessageFormat
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]
\u221E
as equivalent to infinity(INF).Note:
ChoiceFormat
differs from the otherFormat
classes in that you create aChoiceFormat
object with a constructor (not with agetInstance
style factory method). The factory methods aren't necessary becauseChoiceFormat
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)); }
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));
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.
- See Also:
DecimalFormat
,MessageFormat
, Serialized Form
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Nested Class Summary
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Nested classes/interfaces inherited from class java.text.NumberFormat
NumberFormat.Field
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Field Summary
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Fields inherited from class java.text.NumberFormat
FRACTION_FIELD, INTEGER_FIELD
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Constructor Summary
Constructors Constructor and 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.
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Method Summary
Methods Modifier and Type Method and Description void
applyPattern(String newPattern)
Sets the pattern.Object
clone()
Overrides Cloneableboolean
equals(Object obj)
Equality comparision between twoStringBuffer
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 d.static double
nextDouble(double d, boolean positive)
Finds the least double greater than d (if positive == true), or the greatest double less than d (if positive == false).Number
parse(String text, ParsePosition status)
Parses a Number from the input text.static double
previousDouble(double d)
Finds the greatest double less than d.void
setChoices(double[] limits, String[] formats)
Set the choices to be used in formatting.String
toPattern()
Gets the pattern.-
Methods inherited from 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
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Methods inherited from class java.text.Format
format, formatToCharacterIterator, parseObject
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Constructor Detail
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ChoiceFormat
public ChoiceFormat(String newPattern)
Constructs with limits and corresponding formats based on the pattern.- See Also:
applyPattern(java.lang.String)
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ChoiceFormat
public ChoiceFormat(double[] limits, String[] formats)
Constructs with the limits and the corresponding formats.
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Method Detail
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applyPattern
public void applyPattern(String newPattern)
Sets the pattern.- Parameters:
newPattern
- See the class description.
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toPattern
public String toPattern()
Gets the pattern.
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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.
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getLimits
public double[] getLimits()
Get the limits passed in the constructor.- Returns:
- the limits.
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getFormats
public Object[] getFormats()
Get the formats passed in the constructor.- Returns:
- the formats.
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format
public StringBuffer format(long number, StringBuffer toAppendTo, FieldPosition status)
Specialization of format. This method really callsformat(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
- See Also:
Format.format(java.lang.Object)
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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 & substituted.toAppendTo
- where text is appended.status
- ignore no useful status is returned.- See Also:
Format.format(java.lang.Object)
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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 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.- Returns:
- A Number representing the value of the number parsed.
- See Also:
NumberFormat.isParseIntegerOnly()
,Format.parseObject(java.lang.String, java.text.ParsePosition)
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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(double)
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previousDouble
public static final double previousDouble(double d)
Finds the greatest double less than d. If NaN, returns same value.- See Also:
nextDouble(double)
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clone
public Object clone()
Overrides Cloneable- Overrides:
clone
in classNumberFormat
- Returns:
- a clone of this instance.
- See Also:
Cloneable
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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)
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equals
public boolean equals(Object obj)
Equality comparision 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
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nextDouble
public static double nextDouble(double d, boolean positive)
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)
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Document heeft de 11/06/2005 gemaakt, de laatste keer de 04/03/2020 gewijzigd
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