ChoiceFormat (Java Platform SE 8 )

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
```
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.
See Also: DecimalFormat, MessageFormat, Serialized Form










Nested Class Summary




Nested classes/interfaces inherited from class java.text.NumberFormat
NumberFormat.Field








Field Summary




Fields inherited from class java.text.NumberFormat
FRACTION_FIELD, INTEGER_FIELD








Constructor Summary

Constructors 

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

All Methods Static Methods Instance Methods Concrete Methods 

Modifier and Type
Method
Description


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 is
 true), or the greatest double less than d (if
 positive is 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





Methods inherited from class java.text.Format
format, formatToCharacterIterator, parseObject





Methods inherited from 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
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
See Also:
setChoices(double[], java.lang.String[])










Method Detail





applyPattern
public void applyPattern(String newPattern)
Sets the pattern.

Parameters:
newPattern - See the class description.








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.








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 class NumberFormat
Parameters:
number - the long number to format
toAppendTo - the StringBuffer to which the formatted text is to be
                   appended
status - the field position
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 class NumberFormat
Parameters:
number - number to be formatted and substituted.
toAppendTo - where text is appended.
status - ignore no useful status is returned.
Returns:
the formatted StringBuffer
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 class NumberFormat
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.
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 class NumberFormat
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 class NumberFormat
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 comparision between two

Overrides:
equals in class NumberFormat
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

Modifier and Type	Method	Description
`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` is `true`), or the greatest double less than `d` (if `positive` is `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.

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.

Class ChoiceFormat

Synchronization

Nested Class Summary

Nested classes/interfaces inherited from class java.text.NumberFormat

Field Summary

Fields inherited from class java.text.NumberFormat

Constructor Summary

Method Summary

Methods inherited from class java.text.NumberFormat

Methods inherited from class java.text.Format

Methods inherited from class java.lang.Object

Constructor Detail

ChoiceFormat

ChoiceFormat

Method Detail

applyPattern

toPattern

setChoices

getLimits

getFormats

format

format

parse

nextDouble

previousDouble

clone

hashCode

equals

nextDouble