public abstract 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:
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);
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.
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 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.
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.
DecimalFormat,
ChoiceFormat| Modifier and Type | Field and Description |
|---|---|
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 and Description |
|---|
NumberFormat() |
| Modifier and Type | Method and Description |
|---|---|
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 an object to produce a string.
|
static Locale[] |
getAvailableLocales()
Get the set of Locales for which NumberFormats are installed
|
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 the default number format for the current default locale.
|
static NumberFormat |
getInstance(Locale inLocale)
Returns the default 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.
|
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 text)
Convenience method.
|
abstract Number |
parse(String text,
ParsePosition parsePosition)
Returns a Long if possible (e.g.
|
Object |
parseObject(String source,
ParsePosition parsePosition)
Parses a string to produce an object.
|
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.
|
format, parseObjectpublic static final int INTEGER_FIELD
FieldPosition,
Constant Field Valuespublic static final int FRACTION_FIELD
FieldPosition,
Constant Field Valuespublic final StringBuffer format(Object number, StringBuffer toAppendTo, FieldPosition pos)
FormatStringBuffer format (Number obj, StringBuffer toAppendTo) Number parse (String str)These general routines allow polymorphic parsing and formatting for objects such as the MessageFormat.
format in class Formatnumber - The object to formattoAppendTo - where the text is to be appended
On output: the offsets of the alignment field.pos - positionMessageFormat,
FieldPositionpublic final Object parseObject(String source, ParsePosition parsePosition)
Format
String format (Number obj);
String format (long obj);
String format (double obj);
Number parse (String str);
Before calling, set status.index to the offset you want to start parsing at in the source. After calling, status.index is the end of the text you parsed. If error occurs, index is unchanged.
When parsing, leading whitespace is discarded (with successful parse), while trailing whitespace is left as is.
Example: Parsing "_12_xy" (where _ represents a space) for a number, with index == 0 will result in the number 12, with status.index updated to 3 (just before the second space). Parsing a second time will result in a ParseException since "xy" is not a number, and leave index at 3.
Subclasses will typically supply specific parse methods that return different types of values. Since methods can't overload on return types, these will typically be named "parse", while this polymorphic method will always be called parseObject. Any parse method that does not take a status should throw ParseException when no text in the required format is at the start position.
parseObject in class Formatsource - ?parsePosition - ?ParsePositionpublic final String format(double number)
number - ?Format.format(java.lang.Object)public final String format(long number)
number - ?Format.format(java.lang.Object)public abstract StringBuffer format(double number, StringBuffer toAppendTo, FieldPosition pos)
number - ?toAppendTo - ?pos - ?Format.format(java.lang.Object)public abstract StringBuffer format(long number, StringBuffer toAppendTo, FieldPosition pos)
number - ?toAppendTo - ?pos - ?Format.format(java.lang.Object)public abstract Number parse(String text, ParsePosition parsePosition)
text - ?parsePosition - ?isParseIntegerOnly(),
Format.parseObject(java.lang.String, java.text.ParsePosition)public Number parse(String text) throws ParseException
text - ?ParseException - if the specified string is invalid.format(java.lang.Object, java.lang.StringBuffer, java.text.FieldPosition)public boolean isParseIntegerOnly()
public void setParseIntegerOnly(boolean value)
value - ?isParseIntegerOnly()public static final NumberFormat getInstance()
public static NumberFormat getInstance(Locale inLocale)
inLocale - localepublic static final NumberFormat getNumberInstance()
public static NumberFormat getNumberInstance(Locale inLocale)
inLocale - localepublic static final NumberFormat getCurrencyInstance()
public static NumberFormat getCurrencyInstance(Locale inLocale)
inLocale - localepublic static final NumberFormat getPercentInstance()
public static NumberFormat getPercentInstance(Locale inLocale)
inLocale - localepublic static Locale[] getAvailableLocales()
public int hashCode()
hashCode in class ObjectObject.equals(java.lang.Object),
Hashtablepublic boolean equals(Object obj)
equals in class Objectobj - the reference object with which to compare.true if this object is the same as the obj
argument; false otherwise.Boolean.hashCode(),
Hashtablepublic Object clone()
public boolean isGroupingUsed()
setGroupingUsed(boolean)public void setGroupingUsed(boolean newValue)
newValue - true if the grouping is the be usedisGroupingUsed()public int getMaximumIntegerDigits()
setMaximumIntegerDigits(int)public void setMaximumIntegerDigits(int newValue)
newValue - digit countgetMaximumIntegerDigits()public int getMinimumIntegerDigits()
setMinimumIntegerDigits(int)public void setMinimumIntegerDigits(int newValue)
newValue - digit countgetMinimumIntegerDigits()public int getMaximumFractionDigits()
setMaximumFractionDigits(int)public void setMaximumFractionDigits(int newValue)
newValue - digit countgetMaximumFractionDigits()public int getMinimumFractionDigits()
setMinimumFractionDigits(int)public void setMinimumFractionDigits(int newValue)
newValue - new digit countgetMinimumFractionDigits()