java.lang.Objectjava.text.Format
java.text.NumberFormat
java.text.ChoiceFormat
public class 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 accepts \u221E as equivalent to infinity(INF).X matches j if and only if limit[j] <= X < limit[j+1]
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,
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
monthNames= {"Sun","Mon","Tue","Wed","Thur","Fri","Sat"}; ChoiceFormat form = new ChoiceFormat(limits,dayOfWeekNames);
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)); }
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.
Nested Class Summary |
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Nested classes/interfaces inherited from class java.text. NumberFormat |
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NumberFormat.Field |
Field Summary |
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Fields inherited from class java.text. NumberFormat |
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FRACTION_FIELD , INTEGER_FIELD |
Constructor Summary | |
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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 | |
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void |
applyPattern
(
String
newPattern) Sets the pattern. |
Object |
clone
() Overrides Cloneable |
boolean |
equals
(
Object
obj) Equality comparision 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 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. Format |
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format , formatToCharacterIterator , parseObject |
Methods inherited from class java.lang. Object |
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finalize , getClass , notify , notifyAll , toString , wait , wait , wait |
Constructor Detail |
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public ChoiceFormat(String newPattern)
public ChoiceFormat(double[] limits, String[] formats)
Method Detail |
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public void applyPattern(String newPattern)
public String toPattern()
public void setChoices(double[] limits, String[] formats)
public double[] getLimits()
public Object[] getFormats()
public StringBuffer format(long number, StringBuffer toAppendTo, FieldPosition status)
public StringBuffer format(double number, StringBuffer toAppendTo, FieldPosition status)
public Number parse(String text, ParsePosition status)
public static final double nextDouble(double d)
Used to make half-open intervals.
public static final double previousDouble(double d)
public Object clone()
public int hashCode()
public boolean equals(Object obj)
public static double nextDouble(double d, boolean positive)