public class ChoiceFormat extends NumberFormat
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:
double[] limits = {1,2,3,4,5,6,7};
String[] monthNames = {"Sun","Mon","Tue","Wed","Thur","Fri","Sat"};
ChoiceFormat form = new ChoiceFormat(limits, 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));
}
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.
DecimalFormat,
MessageFormatFRACTION_FIELD, INTEGER_FIELD| 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.
|
| Modifier and Type | Method and 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 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.
|
format, format, format, getAvailableLocales, getCurrencyInstance, getCurrencyInstance, getInstance, getInstance, getMaximumFractionDigits, getMaximumIntegerDigits, getMinimumFractionDigits, getMinimumIntegerDigits, getNumberInstance, getNumberInstance, getPercentInstance, getPercentInstance, isGroupingUsed, isParseIntegerOnly, parse, parseObject, setGroupingUsed, setMaximumFractionDigits, setMaximumIntegerDigits, setMinimumFractionDigits, setMinimumIntegerDigits, setParseIntegerOnlyformat, parseObjectpublic ChoiceFormat(String newPattern)
newPattern - ?public ChoiceFormat(double[] limits,
String[] formats)
limits - ?formats - ?setChoices(double[], java.lang.String[])public void applyPattern(String newPattern)
newPattern - See the class description.public String toPattern()
public void setChoices(double[] limits,
String[] formats)
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.public double[] getLimits()
public Object[] getFormats()
public StringBuffer format(long number, StringBuffer toAppendTo, FieldPosition status)
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.format in class NumberFormatstatus - positionnumber - ?toAppendTo - ?Format.format(java.lang.Object)public StringBuffer format(double number, StringBuffer toAppendTo, FieldPosition status)
format in class NumberFormatnumber - number to be formatted and substituted.toAppendTo - where text is appended.status - ignore no useful status is returned.Format.format(java.lang.Object)public Number parse(String text, ParsePosition status)
parse in class NumberFormattext - 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.NumberFormat.isParseIntegerOnly(),
Format.parseObject(java.lang.String, java.text.ParsePosition)public static final double nextDouble(double d)
Used to make half-open intervals.
d - ?previousDouble(double)public static final double previousDouble(double d)
d - ?nextDouble(double)public Object clone()
clone in class NumberFormatCloneablepublic int hashCode()
hashCode in class NumberFormatObject.equals(java.lang.Object),
Hashtablepublic boolean equals(Object obj)
equals in class NumberFormatobj - the reference object with which to compare.Boolean.hashCode(),
Hashtablepublic static double nextDouble(double d,
boolean positive)
d - ?positive - ?