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java.lang.Object | +----java.text.Format | +----java.text.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 < a.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 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.
Field Summary | |
static int | FRACTION_FIELD
|
static int | INTEGER_FIELD
|
Constructor Summary | |
NumberFormat()
|
Method Summary | |
Object | clone()
|
boolean | equals(Object obj)
|
StringBuffer | format(Object number,
StringBuffer toAppendTo,
FieldPosition pos)
|
String | format(double number)
|
String | format(long number)
|
StringBuffer | format(double number,
StringBuffer toAppendTo,
FieldPosition pos)
|
StringBuffer | format(long number,
StringBuffer toAppendTo,
FieldPosition pos)
|
static Locale[] | getAvailableLocales()
|
static NumberFormat | getCurrencyInstance()
|
static NumberFormat | getCurrencyInstance(Locale inLocale)
|
static NumberFormat | getInstance()
|
static NumberFormat | getInstance(Locale inLocale)
|
int | getMaximumFractionDigits()
|
int | getMaximumIntegerDigits()
|
int | getMinimumFractionDigits()
|
int | getMinimumIntegerDigits()
|
static NumberFormat | getNumberInstance()
|
static NumberFormat | getNumberInstance(Locale inLocale)
|
static NumberFormat | getPercentInstance()
|
static NumberFormat | getPercentInstance(Locale inLocale)
|
int | hashCode()
|
boolean | isGroupingUsed()
|
boolean | isParseIntegerOnly()
|
Number | parse(String text,
ParsePosition parsePosition)
|
Number | parse(String text)
|
Object | parseObject(String source,
ParsePosition parsePosition)
|
void | setGroupingUsed(boolean newValue)
|
void | setMaximumFractionDigits(int newValue)
|
void | setMaximumIntegerDigits(int newValue)
|
void | setMinimumFractionDigits(int newValue)
|
void | setMinimumIntegerDigits(int newValue)
|
void | setParseIntegerOnly(boolean value)
|
Methods inherited from class java.text.Format |
clone, format, format, parseObject, parseObject |
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
public static final int INTEGER_FIELD
public static final int FRACTION_FIELD
Constructor Detail |
public NumberFormat()
Method Detail |
public final StringBuffer format(Object number, StringBuffer toAppendTo, FieldPosition pos)
public final Object parseObject(String source, ParsePosition parsePosition)
public final String format(double number)
public final String format(long number)
public abstract StringBuffer format(double number, StringBuffer toAppendTo, FieldPosition pos)
public abstract StringBuffer format(long number, StringBuffer toAppendTo, FieldPosition pos)
public abstract Number parse(String text, ParsePosition parsePosition)
public Number parse(String text) throws ParseException
public boolean isParseIntegerOnly()
public void setParseIntegerOnly(boolean value)
public static final NumberFormat getInstance()
public static NumberFormat getInstance(Locale inLocale)
public static final NumberFormat getNumberInstance()
public static NumberFormat getNumberInstance(Locale inLocale)
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()
public int hashCode()
public boolean equals(Object obj)
public Object clone()
public boolean isGroupingUsed()
public void setGroupingUsed(boolean newValue)
public int getMaximumIntegerDigits()
public void setMaximumIntegerDigits(int newValue)
public int getMinimumIntegerDigits()
public void setMinimumIntegerDigits(int newValue)
public int getMaximumFractionDigits()
public void setMaximumFractionDigits(int newValue)
public int getMinimumFractionDigits()
public void setMinimumFractionDigits(int newValue)
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