ChoiceFormat

java.lang.Object
- java.text.Format
- - java.text.NumberFormat
  - - java.text.ChoiceFormat

所有已实现的接口:: 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.

另请参阅:: DecimalFormat, MessageFormat, 序列化表格

嵌套类概要
- 从类继承的嵌套类/接口 java.text.NumberFormat
  NumberFormat.Field

字段概要
- 从类继承的字段 java.text.NumberFormat
  FRACTION_FIELD, INTEGER_FIELD

构造器概要

构造器
构造器	说明
`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.

方法概要

所有方法静态方法实例方法具体方法
限定符和类型	方法	说明
`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.

从类继承的方法 java.text.Format
format, formatToCharacterIterator, parseObject

从类继承的方法 java.lang.Object
finalize, getClass, notify, notifyAll, toString, wait, wait, wait

- 构造器详细资料
  - ChoiceFormat
```
public ChoiceFormat(String newPattern)
```
    Constructs with limits and corresponding formats based on the pattern.
    
    参数:
    
    newPattern - the new pattern string
    
    另请参阅:
    
    applyPattern(java.lang.String)
  - ChoiceFormat
```
public ChoiceFormat(double[] limits,
                    String[] formats)
```
    Constructs with the limits and the corresponding formats.
    
    参数:
    
    limits - limits in ascending order
    
    formats - corresponding format strings
    
    另请参阅:
    
    setChoices(double[], java.lang.String[])
- 方法详细资料
  - applyPattern
```
public void applyPattern(String newPattern)
```
    Sets the pattern.
    
    参数:
    
    newPattern - See the class description.
  - toPattern
```
public String toPattern()
```
    Gets the pattern.
    
    返回:
    
    the pattern string
  - setChoices
```
public void setChoices(double[] limits,
                       String[] formats)
```
    Set the choices to be used in formatting.
    
    参数:
    
    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.
    
    返回:
    
    the limits.
  - getFormats
```
public Object[] getFormats()
```
    Get the formats passed in the constructor.
    
    返回:
    
    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.
    
    指定者:
    
    format 在类中 NumberFormat
    
    参数:
    
    number - the long number to format
    
    toAppendTo - the StringBuffer to which the formatted text is to be appended
    
    status - the field position
    
    返回:
    
    the formatted StringBuffer
    
    另请参阅:
    
    Format.format(java.lang.Object)
  - format
```
public StringBuffer format(double number,
                           StringBuffer toAppendTo,
                           FieldPosition status)
```
    Returns pattern with formatted double.
    
    指定者:
    
    format 在类中 NumberFormat
    
    参数:
    
    number - number to be formatted and substituted.
    
    toAppendTo - where text is appended.
    
    status - ignore no useful status is returned.
    
    返回:
    
    the formatted StringBuffer
    
    另请参阅:
    
    Format.format(java.lang.Object)
  - parse
```
public Number parse(String text,
                    ParsePosition status)
```
    Parses a Number from the input text.
    
    指定者:
    
    parse 在类中 NumberFormat
    
    参数:
    
    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.
    
    返回:
    
    A Number representing the value of the number parsed.
    
    另请参阅:
    
    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.
    
    参数:
    
    d - the reference value
    
    返回:
    
    the least double value greather than d
    
    另请参阅:
    
    previousDouble(double)
  - previousDouble
```
public static final double previousDouble(double d)
```
    Finds the greatest double less than d. If NaN, returns same value.
    
    参数:
    
    d - the reference value
    
    返回:
    
    the greatest double value less than d
    
    另请参阅:
    
    nextDouble(double)
  - clone
```
public Object clone()
```
    Overrides Cloneable
    
    覆盖:
    
    clone 在类中 NumberFormat
    
    返回:
    
    a clone of this instance.
    
    另请参阅:
    
    Cloneable
  - hashCode
```
public int hashCode()
```
    Generates a hash code for the message format object.
    
    覆盖:
    
    hashCode 在类中 NumberFormat
    
    返回:
    
    a hash code value for this object.
    
    另请参阅:
    
    Object.equals(java.lang.Object), System.identityHashCode(java.lang.Object)
  - equals
```
public boolean equals(Object obj)
```
    Equality comparision between two
    
    覆盖:
    
    equals 在类中 NumberFormat
    
    参数:
    
    obj - the reference object with which to compare.
    
    返回:
    
    true if this object is the same as the obj argument; false otherwise.
    
    另请参阅:
    
    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)
    
    参数:
    
    d - the reference value
    
    positive - true if the least double is desired; false otherwise
    
    返回:
    
    the least or greater double value

类 ChoiceFormat

Synchronization

嵌套类概要

从类继承的嵌套类/接口 java.text.NumberFormat

字段概要

从类继承的字段 java.text.NumberFormat

构造器概要

方法概要

从类继承的方法 java.text.Format

从类继承的方法 java.text.NumberFormat

从类继承的方法 java.lang.Object

构造器详细资料

ChoiceFormat

ChoiceFormat

方法详细资料

applyPattern

toPattern

setChoices

getLimits

getFormats

format

format

parse

nextDouble

previousDouble

clone

hashCode

equals

nextDouble