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Java™ Platform Standard Ed. 6 |
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java.lang.Object java.text.Format java.text.NumberFormat
public abstract class NumberFormat
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:
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.myString = NumberFormat.getInstance().format(myNumber);
To format a number for a different Locale, specify it in the call toNumberFormat nf = NumberFormat.getInstance(); for (int i = 0; i < myNumber.length; ++i) { output.println(nf.format(myNumber[i]) + "; "); }
getInstance
.
You can also use aNumberFormat nf = NumberFormat.getInstance(Locale.FRENCH);
NumberFormat
to parse numbers:
UsemyNumber = nf.parse(myString);
getInstance
or getNumberInstance
to get the
normal number format. Use getIntegerInstance
to get an
integer 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 DecimalFormat
. 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.
NumberFormat and DecimalFormat are designed such that some controls work for formatting and others work for parsing. The following is the detailed description for each these control methods,
setParseIntegerOnly : only affects parsing, e.g. if true, "3456.78" -> 3456 (and leaves the parse position just after index 6) if false, "3456.78" -> 3456.78 (and leaves the parse position just after index 8) This is independent of formatting. If you want to not show a decimal point where there might be no digits after the decimal point, use setDecimalSeparatorAlwaysShown.
setDecimalSeparatorAlwaysShown : only affects formatting, and only where there might be no digits after the decimal point, such as with a pattern like "#,##0.##", e.g., if true, 3456.00 -> "3,456." if false, 3456.00 -> "3456" This is independent of parsing. If you want parsing to stop at the decimal point, use setParseIntegerOnly.
You can also use forms of the parse
and format
methods with ParsePosition
and FieldPosition
to
allow you to:
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.
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.
Number formats are generally 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.
DecimalFormat
,
ChoiceFormat
,
Serialized FormNested Class Summary | |
---|---|
static class |
NumberFormat.Field
Defines constants that are used as attribute keys in the AttributedCharacterIterator returned
from NumberFormat.formatToCharacterIterator and as
field identifiers in FieldPosition . |
Field Summary | |
---|---|
static int |
FRACTION_FIELD
Field constant used to construct a FieldPosition object. |
static int |
INTEGER_FIELD
Field constant used to construct a FieldPosition object. |
Constructor Summary | |
---|---|
protected |
NumberFormat()
Sole constructor. |
Method Summary | |
---|---|
Object |
clone()
Overrides Cloneable |
boolean |
equals(Object obj)
Overrides equals |
String |
format(double number)
Specialization of format. |
abstract StringBuffer |
format(double number,
StringBuffer toAppendTo,
FieldPosition pos)
Specialization of format. |
String |
format(long number)
Specialization of format. |
abstract StringBuffer |
format(long number,
StringBuffer toAppendTo,
FieldPosition pos)
Specialization of format. |
StringBuffer |
format(Object number,
StringBuffer toAppendTo,
FieldPosition pos)
Formats a number and appends the resulting text to the given string buffer. |
static Locale[] |
getAvailableLocales()
Returns an array of all locales for which the get*Instance methods of this class can return
localized instances. |
Currency |
getCurrency()
Gets the currency used by this number format when formatting currency values. |
static NumberFormat |
getCurrencyInstance()
Returns a currency format for the current default locale. |
static NumberFormat |
getCurrencyInstance(Locale inLocale)
Returns a currency format for the specified locale. |
static NumberFormat |
getInstance()
Returns a general-purpose number format for the current default locale. |
static NumberFormat |
getInstance(Locale inLocale)
Returns a general-purpose number format for the specified locale. |
static NumberFormat |
getIntegerInstance()
Returns an integer number format for the current default locale. |
static NumberFormat |
getIntegerInstance(Locale inLocale)
Returns an integer number format for the specified locale. |
int |
getMaximumFractionDigits()
Returns the maximum number of digits allowed in the fraction portion of a number. |
int |
getMaximumIntegerDigits()
Returns the maximum number of digits allowed in the integer portion of a number. |
int |
getMinimumFractionDigits()
Returns the minimum number of digits allowed in the fraction portion of a number. |
int |
getMinimumIntegerDigits()
Returns the minimum number of digits allowed in the integer portion of a number. |
static NumberFormat |
getNumberInstance()
Returns a general-purpose number format for the current default locale. |
static NumberFormat |
getNumberInstance(Locale inLocale)
Returns a general-purpose number format for the specified locale. |
static NumberFormat |
getPercentInstance()
Returns a percentage format for the current default locale. |
static NumberFormat |
getPercentInstance(Locale inLocale)
Returns a percentage format for the specified locale. |
RoundingMode |
getRoundingMode()
Gets the RoundingMode used in this NumberFormat. |
int |
hashCode()
Overrides hashCode |
boolean |
isGroupingUsed()
Returns true if grouping is used in this format. |
boolean |
isParseIntegerOnly()
Returns true if this format will parse numbers as integers only. |
Number |
parse(String source)
Parses text from the beginning of the given string to produce a number. |
abstract Number |
parse(String source,
ParsePosition parsePosition)
Returns a Long if possible (e.g., within the range [Long.MIN_VALUE, Long.MAX_VALUE] and with no decimals), otherwise a Double. |
Object |
parseObject(String source,
ParsePosition pos)
Parses text from a string to produce a Number . |
void |
setCurrency(Currency currency)
Sets the currency used by this number format when formatting currency values. |
void |
setGroupingUsed(boolean newValue)
Set whether or not grouping will be used in this format. |
void |
setMaximumFractionDigits(int newValue)
Sets the maximum number of digits allowed in the fraction portion of a number. |
void |
setMaximumIntegerDigits(int newValue)
Sets the maximum number of digits allowed in the integer portion of a number. |
void |
setMinimumFractionDigits(int newValue)
Sets the minimum number of digits allowed in the fraction portion of a number. |
void |
setMinimumIntegerDigits(int newValue)
Sets the minimum number of digits allowed in the integer portion of a number. |
void |
setParseIntegerOnly(boolean value)
Sets whether or not numbers should be parsed as integers only. |
void |
setRoundingMode(RoundingMode roundingMode)
Sets the RoundingMode used in this NumberFormat. |
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 |
Field Detail |
---|
public static final int INTEGER_FIELD
FieldPosition
,
Constant Field Valuespublic static final int FRACTION_FIELD
FieldPosition
,
Constant Field ValuesConstructor Detail |
---|
protected NumberFormat()
Method Detail |
---|
public StringBuffer format(Object number, StringBuffer toAppendTo, FieldPosition pos)
Number
.
This implementation extracts the number's value using
Number.longValue()
for all integral type values that
can be converted to long
without loss of information,
including BigInteger
values with a
bit length
of less than 64,
and Number.doubleValue()
for all other types. It
then calls
format(long,java.lang.StringBuffer,java.text.FieldPosition)
or format(double,java.lang.StringBuffer,java.text.FieldPosition)
.
This may result in loss of magnitude information and precision for
BigInteger
and BigDecimal
values.
format
in class Format
number
- the number to formattoAppendTo
- the StringBuffer
to which the formatted
text is to be appendedpos
- On input: an alignment field, if desired.
On output: the offsets of the alignment field.
toAppendTo
IllegalArgumentException
- if number
is
null or not an instance of Number
.
NullPointerException
- if toAppendTo
or
pos
is null
ArithmeticException
- if rounding is needed with rounding
mode being set to RoundingMode.UNNECESSARYFieldPosition
public final Object parseObject(String source, ParsePosition pos)
Number
.
The method attempts to parse text starting at the index given by
pos
.
If parsing succeeds, then the index of pos
is updated
to the index after the last character used (parsing does not necessarily
use all characters up to the end of the string), and the parsed
number is returned. The updated pos
can be used to
indicate the starting point for the next call to this method.
If an error occurs, then the index of pos
is not
changed, the error index of pos
is set to the index of
the character where the error occurred, and null is returned.
See the parse(String, ParsePosition)
method for more information
on number parsing.
parseObject
in class Format
source
- A String
, part of which should be parsed.pos
- A ParsePosition
object with index and error
index information as described above.
Number
parsed from the string. In case of
error, returns null.
NullPointerException
- if pos
is null.public final String format(double number)
ArithmeticException
- if rounding is needed with rounding
mode being set to RoundingMode.UNNECESSARYFormat.format(java.lang.Object)
public final String format(long number)
ArithmeticException
- if rounding is needed with rounding
mode being set to RoundingMode.UNNECESSARYFormat.format(java.lang.Object)
public abstract StringBuffer format(double number, StringBuffer toAppendTo, FieldPosition pos)
ArithmeticException
- if rounding is needed with rounding
mode being set to RoundingMode.UNNECESSARYFormat.format(java.lang.Object)
public abstract StringBuffer format(long number, StringBuffer toAppendTo, FieldPosition pos)
ArithmeticException
- if rounding is needed with rounding
mode being set to RoundingMode.UNNECESSARYFormat.format(java.lang.Object)
public abstract Number parse(String source, ParsePosition parsePosition)
isParseIntegerOnly()
,
Format.parseObject(java.lang.String, java.text.ParsePosition)
public Number parse(String source) throws ParseException
See the parse(String, ParsePosition)
method for more information
on number parsing.
source
- A String
whose beginning should be parsed.
Number
parsed from the string.
ParseException
- if the beginning of the specified string
cannot be parsed.public boolean isParseIntegerOnly()
public void setParseIntegerOnly(boolean value)
isParseIntegerOnly()
public static final NumberFormat getInstance()
getNumberInstance()
.
public static NumberFormat getInstance(Locale inLocale)
getNumberInstance(inLocale)
.
public static final NumberFormat getNumberInstance()
public static NumberFormat getNumberInstance(Locale inLocale)
public static final NumberFormat getIntegerInstance()
RoundingMode.HALF_EVEN
) for formatting,
and to parse only the integer part of an input string (see isParseIntegerOnly
).
getRoundingMode()
public static NumberFormat getIntegerInstance(Locale inLocale)
RoundingMode.HALF_EVEN
) for formatting,
and to parse only the integer part of an input string (see isParseIntegerOnly
).
getRoundingMode()
public static final NumberFormat getCurrencyInstance()
public static NumberFormat getCurrencyInstance(Locale inLocale)
public static final NumberFormat getPercentInstance()
public static NumberFormat getPercentInstance(Locale inLocale)
public static Locale[] getAvailableLocales()
get*Instance
methods of this class can return
localized instances.
The returned array represents the union of locales supported by the Java
runtime and by installed
NumberFormatProvider
implementations.
It must contain at least a Locale
instance equal to
Locale.US
.
NumberFormat
instances are available.public int hashCode()
hashCode
in class Object
Object.equals(java.lang.Object)
,
Hashtable
public boolean equals(Object obj)
equals
in class Object
obj
- the reference object with which to compare.
true
if this object is the same as the obj
argument; false
otherwise.Object.hashCode()
,
Hashtable
public Object clone()
clone
in class Format
Cloneable
public boolean isGroupingUsed()
setGroupingUsed(boolean)
public void setGroupingUsed(boolean newValue)
isGroupingUsed()
public int getMaximumIntegerDigits()
setMaximumIntegerDigits(int)
public void setMaximumIntegerDigits(int newValue)
newValue
- the maximum number of integer digits to be shown; if
less than zero, then zero is used. The concrete subclass may enforce an
upper limit to this value appropriate to the numeric type being formatted.getMaximumIntegerDigits()
public int getMinimumIntegerDigits()
setMinimumIntegerDigits(int)
public void setMinimumIntegerDigits(int newValue)
newValue
- the minimum number of integer digits to be shown; if
less than zero, then zero is used. The concrete subclass may enforce an
upper limit to this value appropriate to the numeric type being formatted.getMinimumIntegerDigits()
public int getMaximumFractionDigits()
setMaximumFractionDigits(int)
public void setMaximumFractionDigits(int newValue)
newValue
- the maximum number of fraction digits to be shown; if
less than zero, then zero is used. The concrete subclass may enforce an
upper limit to this value appropriate to the numeric type being formatted.getMaximumFractionDigits()
public int getMinimumFractionDigits()
setMinimumFractionDigits(int)
public void setMinimumFractionDigits(int newValue)
newValue
- the minimum number of fraction digits to be shown; if
less than zero, then zero is used. The concrete subclass may enforce an
upper limit to this value appropriate to the numeric type being formatted.getMinimumFractionDigits()
public Currency getCurrency()
setCurrency
.
The default implementation throws
UnsupportedOperationException
.
null
UnsupportedOperationException
- if the number format class
doesn't implement currency formattingpublic void setCurrency(Currency currency)
The default implementation throws
UnsupportedOperationException
.
currency
- the new currency to be used by this number format
UnsupportedOperationException
- if the number format class
doesn't implement currency formatting
NullPointerException
- if currency
is nullpublic RoundingMode getRoundingMode()
RoundingMode
used in this NumberFormat.
The default implementation of this method in NumberFormat
always throws UnsupportedOperationException
.
Subclasses which handle different rounding modes should override
this method.
RoundingMode
used for this NumberFormat.
UnsupportedOperationException
- The default implementation
always throws this exceptionsetRoundingMode(RoundingMode)
public void setRoundingMode(RoundingMode roundingMode)
RoundingMode
used in this NumberFormat.
The default implementation of this method in NumberFormat always
throws UnsupportedOperationException
.
Subclasses which handle different rounding modes should override
this method.
roundingMode
- The RoundingMode
to be used
UnsupportedOperationException
- The default implementation
always throws this exception
NullPointerException
- if roundingMode
is nullgetRoundingMode()
|
Java™ Platform Standard Ed. 6 |
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