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Class java.text.NumberFormat 

java.lang.Object
   |
   +----java.text.Format
           |
           +----java.text.NumberFormat
public class NumberFormat
extends Format
implements Cloneable
NumberFormat is the abstract base class for all number formats. This class provides the interface for formatting and parsing numbers. NumberFormat also provides methods for determining which locales have number formats, and what their names are.

NumberFormat helps you to format and parse numbers for any locale. Your code can be completely independent of the locale conventions for decimal points, thousands-separators, or even the particular decimal digits used, or whether the number format is even decimal.

To format a number for the current Locale, use one of the factory class methods: 

  myString = NumberFormat.getInstance().format(myNumber);
If you are formatting multiple numbers, it is more efficient to get the format and use it multiple times so that the system doesn't have to fetch the information about the local language and country conventions multiple times. 
 NumberFormat nf = NumberFormat.getInstance();
 for (int i = 0; i < a.length; ++i) {
     output.println(nf.format(myNumber[i]) + "; ");
 }
To format a number for a different Locale, specify it in the call to getInstance. 
 NumberFormat nf = NumberFormat.getInstance(Locale.FRENCH);
You can also use a NumberFormat to parse numbers: 
 myNumber = nf.parse(myString);
Use getInstance or getNumberInstance to get the normal number format. Use getCurrencyInstance to get the currency number format. And use getPercentInstance to get a format for displaying percentages. With this format, a fraction like 0.53 is displayed as 53%.

You can also control the display of numbers with such methods as setMinimumFractionDigits. If you want even more control over the format or parsing, or want to give your users more control, you can try casting the NumberFormat you get from the factory methods to a DecimalNumberFormat. This will work for the vast majority of locales; just remember to put it in a try block in case you encounter an unusual one.

You can also use forms of the parse and format methods with ParsePosition and FieldPosition to allow you to:

For example, you can align numbers in two ways:
  1. If you are using a monospaced font with spacing for alignment, you can pass the FieldPosition in your format call, with field = INTEGER_FIELD. On output, getEndIndex will be set to the offset between the last character of the integer and the decimal. Add (desiredSpaceCount - getEndIndex) spaces at the front of the string.
  2. If you are using proportional fonts, instead of padding with spaces, measure the width of the string in pixels from the start to getEndIndex. Then move the pen by (desiredPixelWidth - widthToAlignmentPoint) before drawing the text. It also works where there is no decimal, but possibly additional characters at the end, e.g. with parentheses in negative numbers: "(12)" for -12.

See Also:
DecimalFormat, ChoiceFormat

Variable Index

o FRACTION_FIELD
Field constant used to construct a FieldPosition object.
o INTEGER_FIELD
Field constant used to construct a FieldPosition object.

Constructor Index

o NumberFormat()

Method Index

o clone()
Overrides Cloneable
o equals(Object)
Overrides equals
o format(double)
Specialization of format.
o format(double, StringBuffer, FieldPosition)
Specialization of format.
o format(long)
Specialization of format.
o format(long, StringBuffer, FieldPosition)
Specialization of format.
o format(Object, StringBuffer, FieldPosition)
Formats an object to produce a string.
o getAvailableLocales()
Get the set of Locales for which NumberFormats are installed
o getCurrencyInstance()
Returns a currency format for the current default locale.
o getCurrencyInstance(Locale)
Returns a currency format for the specified locale.
o getInstance()
Returns the default number format for the current default locale.
o getInstance(Locale)
Returns the default number format for the specified locale.
o getMaximumFractionDigits()
Returns the maximum number of digits allowed in the fraction portion of a number.
o getMaximumIntegerDigits()
Returns the maximum number of digits allowed in the integer portion of a number.
o getMinimumFractionDigits()
Returns the minimum number of digits allowed in the fraction portion of a number.
o getMinimumIntegerDigits()
Returns the minimum number of digits allowed in the integer portion of a number.
o getNumberInstance()
Returns a general-purpose number format for the current default locale.
o getNumberInstance(Locale)
Returns a general-purpose number format for the specified locale.
o getPercentInstance()
Returns a percentage format for the current default locale.
o getPercentInstance(Locale)
Returns a percentage format for the specified locale.
o hashCode()
Overrides hashCode
o isGroupingUsed()
Returns true if grouping is used in this format.
o isParseIntegerOnly()
Returns true if this format will parse numbers as integers only.
o parse(String)
Convenience method.
o parse(String, ParsePosition)
Returns a Long if possible (e.g.
o parseObject(String, ParsePosition)
Parses a string to produce an object.
o setGroupingUsed(boolean)
Set whether or not grouping will be used in this format.
o setMaximumFractionDigits(int)
Sets the maximum number of digits allowed in the fraction portion of a number.
o setMaximumIntegerDigits(int)
Sets the maximum number of digits allowed in the integer portion of a number.
o setMinimumFractionDigits(int)
Sets the minimum number of digits allowed in the fraction portion of a number.
o setMinimumIntegerDigits(int)
Sets the minimum number of digits allowed in the integer portion of a number.
o setParseIntegerOnly(boolean)
Sets whether or not numbers should be parsed as integers only.

Variables

o INTEGER_FIELD 
Properties Public Constant 
   INTEGER_FIELD=int
Field constant used to construct a FieldPosition object. Signifies that the position of the integer part of a formatted number should be returned.

See Also:
FieldPosition
o FRACTION_FIELD 
Properties Public Constant 
   FRACTION_FIELD=int
Field constant used to construct a FieldPosition object. Signifies that the position of the fraction part of a formatted number should be returned.

See Also:
FieldPosition

Constructors

o NumberFormat 
    method NumberFormat() public

Methods

o format 
    method format(number=Object, -
                  toAppendTo=StringBuffer, -
                  pos=FieldPosition) returns StringBuffer public   final
Formats an object to produce a string.

Overrides:
format in class Format
o parseObject 
    method parseObject(source=String, -
                       parsePosition=ParsePosition) returns Object public   final
Parses a string to produce an object.

Overrides:
parseObject in class Format
o format 
    method format(number=double) returns String public   final
Specialization of format.

See Also:
format
o format 
    method format(number=long) returns String public   final
Specialization of format.

See Also:
format
o format 
    method format(number=double, -
                  toAppendTo=StringBuffer, -
                  pos=FieldPosition) returns StringBuffer public abstract
Specialization of format.

See Also:
format
o format 
    method format(number=long, -
                  toAppendTo=StringBuffer, -
                  pos=FieldPosition) returns StringBuffer public abstract
Specialization of format.

See Also:
format
o parse 
    method parse(text=String, -
                 parsePosition=ParsePosition) returns Number public abstract
Returns a Long if possible (e.g. within range [Long.MIN_VALUE, Long.MAX_VALUE], and with no decimals), otherwise a Double. If IntegerOnly is set, will stop at a decimal point (or equivalent; e.g. for rational numbers "1 2/3", will stop after the 1). Does not throw an exception; if no object can be parsed, index is unchanged!

See Also:
isParseIntegerOnly, parseObject
o parse 
    method parse(text=String) returns Number public     Signals ParseException
Convenience method.

Throws: ParseException
if the specified string is invalid.
See Also:
format
o isParseIntegerOnly 
    method isParseIntegerOnly() returns boolean public
Returns true if this format will parse numbers as integers only. For example in the English locale, with ParseIntegerOnly true, the string "1234." would be parsed as the integer value 1234 and parsing would stop at the "." character. Of course, the exact format accepted by the parse operation is locale dependant and determined by sub-classes of NumberFormat.

o setParseIntegerOnly 
    method setParseIntegerOnly(value=boolean)  public
Sets whether or not numbers should be parsed as integers only.

See Also:
isParseIntegerOnly
o getInstance 
    method getInstance() returns static NumberFormat public   final
Returns the default number format for the current default locale. The default format is one of the styles provided by the other factory methods: getNumberInstance, getCurrencyInstance or getPercentInstance. Exactly which one is locale dependant.

o getInstance 
    method getInstance(inLocale=Locale) returns NumberFormat public  static
Returns the default number format for the specified locale. The default format is one of the styles provided by the other factory methods: getNumberInstance, getCurrencyInstance or getPercentInstance. Exactly which one is locale dependant.

o getNumberInstance 
    method getNumberInstance() returns static NumberFormat public   final
Returns a general-purpose number format for the current default locale.

o getNumberInstance 
    method getNumberInstance(inLocale=Locale) returns NumberFormat public  static
Returns a general-purpose number format for the specified locale.

o getCurrencyInstance 
    method getCurrencyInstance() returns static NumberFormat public   final
Returns a currency format for the current default locale.

o getCurrencyInstance 
    method getCurrencyInstance(inLocale=Locale) returns NumberFormat public  static
Returns a currency format for the specified locale.

o getPercentInstance 
    method getPercentInstance() returns static NumberFormat public   final
Returns a percentage format for the current default locale.

o getPercentInstance 
    method getPercentInstance(inLocale=Locale) returns NumberFormat public  static
Returns a percentage format for the specified locale.

o getAvailableLocales 
    method getAvailableLocales() returns Locale[] public  static
Get the set of Locales for which NumberFormats are installed

Returns:
available locales
o hashCode 
    method hashCode() returns int public
Overrides hashCode

Overrides:
hashCode in class Object
o equals 
    method equals(obj=Object) returns boolean public
Overrides equals

Overrides:
equals in class Object
o clone 
    method clone() returns Object public
Overrides Cloneable

Overrides:
clone in class Format
o isGroupingUsed 
    method isGroupingUsed() returns boolean public
Returns true if grouping is used in this format. For example, in the English locale, with grouping on, the number 1234567 might be formatted as "1,234,567". The grouping separator as well as the size of each group is locale dependant and is determined by sub-classes of NumberFormat.

See Also:
setGroupingUsed
o setGroupingUsed 
    method setGroupingUsed(newValue=boolean)  public
Set whether or not grouping will be used in this format.

See Also:
isGroupingUsed
o getMaximumIntegerDigits 
    method getMaximumIntegerDigits() returns int public
Returns the maximum number of digits allowed in the integer portion of a number.

See Also:
setMaximumIntegerDigits
o setMaximumIntegerDigits 
    method setMaximumIntegerDigits(newValue=int)  public
Sets the maximum number of digits allowed in the integer portion of a number. maximumIntegerDigits must be >= minimumIntegerDigits. If the new value for maximumIntegerDigits is less than the current value of minimumIntegerDigits, then minimumIntegerDigits will also be set to the new value.

See Also:
getMaximumIntegerDigits
o getMinimumIntegerDigits 
    method getMinimumIntegerDigits() returns int public
Returns the minimum number of digits allowed in the integer portion of a number.

See Also:
setMinimumIntegerDigits
o setMinimumIntegerDigits 
    method setMinimumIntegerDigits(newValue=int)  public
Sets the minimum number of digits allowed in the integer portion of a number. minimumIntegerDigits must be <= maximumIntegerDigits. If the new value for minimumIntegerDigits exceeds the current value of maximumIntegerDigits, then maximumIntegerDigits will also be set to the new value

See Also:
getMinimumIntegerDigits
o getMaximumFractionDigits 
    method getMaximumFractionDigits() returns int public
Returns the maximum number of digits allowed in the fraction portion of a number.

See Also:
setMaximumFractionDigits
o setMaximumFractionDigits 
    method setMaximumFractionDigits(newValue=int)  public
Sets the maximum number of digits allowed in the fraction portion of a number. maximumFractionDigits must be >= minimumFractionDigits. If the new value for maximumFractionDigits is less than the current value of minimumFractionDigits, then minimumFractionDigits will also be set to the new value.

See Also:
getMaximumFractionDigits
o getMinimumFractionDigits 
    method getMinimumFractionDigits() returns int public
Returns the minimum number of digits allowed in the fraction portion of a number.

See Also:
setMinimumFractionDigits
o setMinimumFractionDigits 
    method setMinimumFractionDigits(newValue=int)  public
Sets the minimum number of digits allowed in the fraction portion of a number. minimumFractionDigits must be <= maximumFractionDigits. If the new value for minimumFractionDigits exceeds the current value of maximumFractionDigits, then maximumIntegerDigits will also be set to the new value

See Also:
getMinimumFractionDigits 
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