DecimalFormat

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

所有已实现的接口:: Serializable, Cloneable

public class DecimalFormat
extends NumberFormat

DecimalFormat is a concrete subclass of NumberFormat that formats decimal numbers. It has a variety of features designed to make it possible to parse and format numbers in any locale, including support for Western, Arabic, and Indic digits. It also supports different kinds of numbers, including integers (123), fixed-point numbers (123.4), scientific notation (1.23E4), percentages (12%), and currency amounts ($123). All of these can be localized.

To obtain a NumberFormat for a specific locale, including the default locale, call one of NumberFormat's factory methods, such as getInstance(). In general, do not call the DecimalFormat constructors directly, since the NumberFormat factory methods may return subclasses other than DecimalFormat. If you need to customize the format object, do something like this:

 NumberFormat f = NumberFormat.getInstance(loc);
 if (f instanceof DecimalFormat) {
     ((DecimalFormat) f).setDecimalSeparatorAlwaysShown(true);
 }

A DecimalFormat comprises a pattern and a set of symbols. The pattern may be set directly using applyPattern(), or indirectly using the API methods. The symbols are stored in a DecimalFormatSymbols object. When using the NumberFormat factory methods, the pattern and symbols are read from localized ResourceBundles.

Patterns

DecimalFormat patterns have the following syntax:

 Pattern:
         PositivePattern
         PositivePattern ; NegativePattern
 PositivePattern:
         Prefix_opt Number Suffix_opt
 NegativePattern:
         Prefix_opt Number Suffix_opt
 Prefix:
         any Unicode characters except \uFFFE, \uFFFF, and special characters
 Suffix:
         any Unicode characters except \uFFFE, \uFFFF, and special characters
 Number:
         Integer Exponent_opt
         Integer . Fraction Exponent_opt
 Integer:
         MinimumInteger
         #
         # Integer
         # , Integer
 MinimumInteger:
         0
         0 MinimumInteger
         0 , MinimumInteger
 Fraction:
         MinimumFraction_opt OptionalFraction_opt
 MinimumFraction:
         0 MinimumFraction_opt
 OptionalFraction:
         # OptionalFraction_opt
 Exponent:
         E MinimumExponent
 MinimumExponent:
         0 MinimumExponent_opt

A DecimalFormat pattern contains a positive and negative subpattern, for example, "#,##0.00;(#,##0.00)". Each subpattern has a prefix, numeric part, and suffix. The negative subpattern is optional; if absent, then the positive subpattern prefixed with the localized minus sign ('-' in most locales) is used as the negative subpattern. That is, "0.00" alone is equivalent to "0.00;-0.00". If there is an explicit negative subpattern, it serves only to specify the negative prefix and suffix; the number of digits, minimal digits, and other characteristics are all the same as the positive pattern. That means that "#,##0.0#;(#)" produces precisely the same behavior as "#,##0.0#;(#,##0.0#)".

The prefixes, suffixes, and various symbols used for infinity, digits, thousands separators, decimal separators, etc. may be set to arbitrary values, and they will appear properly during formatting. However, care must be taken that the symbols and strings do not conflict, or parsing will be unreliable. For example, either the positive and negative prefixes or the suffixes must be distinct for DecimalFormat.parse() to be able to distinguish positive from negative values. (If they are identical, then DecimalFormat will behave as if no negative subpattern was specified.) Another example is that the decimal separator and thousands separator should be distinct characters, or parsing will be impossible.

The grouping separator is commonly used for thousands, but in some countries it separates ten-thousands. The grouping size is a constant number of digits between the grouping characters, such as 3 for 100,000,000 or 4 for 1,0000,0000. If you supply a pattern with multiple grouping characters, the interval between the last one and the end of the integer is the one that is used. So "#,##,###,####" == "######,####" == "##,####,####".

Special Pattern Characters

Many characters in a pattern are taken literally; they are matched during parsing and output unchanged during formatting. Special characters, on the other hand, stand for other characters, strings, or classes of characters. They must be quoted, unless noted otherwise, if they are to appear in the prefix or suffix as literals.

The characters listed here are used in non-localized patterns. Localized patterns use the corresponding characters taken from this formatter's DecimalFormatSymbols object instead, and these characters lose their special status. Two exceptions are the currency sign and quote, which are not localized.

Symbol Location Localized? Meaning
0 Number Yes Digit
# Number Yes Digit, zero shows as absent
. Number Yes Decimal separator or monetary decimal separator
- Number Yes Minus sign
, Number Yes Grouping separator
E Number Yes Separates mantissa and exponent in scientific notation. Need not be quoted in prefix or suffix.
; Subpattern boundary Yes Separates positive and negative subpatterns
% Prefix or suffix Yes Multiply by 100 and show as percentage
\u2030 Prefix or suffix Yes Multiply by 1000 and show as per mille value
¤ (\u00A4) Prefix or suffix No Currency sign, replaced by currency symbol. If doubled, replaced by international currency symbol. If present in a pattern, the monetary decimal separator is used instead of the decimal separator.
' Prefix or suffix No Used to quote special characters in a prefix or suffix, for example, "'#'#" formats 123 to "#123". To create a single quote itself, use two in a row: "# o''clock".

Symbol	Location	Localized?	Meaning
`0`	Number	Yes	Digit
`#`	Number	Yes	Digit, zero shows as absent
`.`	Number	Yes	Decimal separator or monetary decimal separator
`-`	Number	Yes	Minus sign
`,`	Number	Yes	Grouping separator
`E`	Number	Yes	Separates mantissa and exponent in scientific notation. Need not be quoted in prefix or suffix.
`;`	Subpattern boundary	Yes	Separates positive and negative subpatterns
`%`	Prefix or suffix	Yes	Multiply by 100 and show as percentage
`\u2030`	Prefix or suffix	Yes	Multiply by 1000 and show as per mille value
`¤` (`\u00A4`)	Prefix or suffix	No	Currency sign, replaced by currency symbol. If doubled, replaced by international currency symbol. If present in a pattern, the monetary decimal separator is used instead of the decimal separator.
`'`	Prefix or suffix	No	Used to quote special characters in a prefix or suffix, for example, `"'#'#"` formats 123 to `"#123"`. To create a single quote itself, use two in a row: `"# o''clock"`.

Scientific Notation

Numbers in scientific notation are expressed as the product of a mantissa and a power of ten, for example, 1234 can be expressed as 1.234 x 10^3. The mantissa is often in the range 1.0 ≤ x < 10.0, but it need not be. DecimalFormat can be instructed to format and parse scientific notation only via a pattern; there is currently no factory method that creates a scientific notation format. In a pattern, the exponent character immediately followed by one or more digit characters indicates scientific notation. Example: "0.###E0" formats the number 1234 as "1.234E3".

The number of digit characters after the exponent character gives the minimum exponent digit count. There is no maximum. Negative exponents are formatted using the localized minus sign, not the prefix and suffix from the pattern. This allows patterns such as "0.###E0 m/s".
The minimum and maximum number of integer digits are interpreted together:
- If the maximum number of integer digits is greater than their minimum number and greater than 1, it forces the exponent to be a multiple of the maximum number of integer digits, and the minimum number of integer digits to be interpreted as 1. The most common use of this is to generate engineering notation, in which the exponent is a multiple of three, e.g., "##0.#####E0". Using this pattern, the number 12345 formats to "12.345E3", and 123456 formats to "123.456E3".
- Otherwise, the minimum number of integer digits is achieved by adjusting the exponent. Example: 0.00123 formatted with "00.###E0" yields "12.3E-4".
The number of significant digits in the mantissa is the sum of the minimum integer and maximum fraction digits, and is unaffected by the maximum integer digits. For example, 12345 formatted with "##0.##E0" is "12.3E3". To show all digits, set the significant digits count to zero. The number of significant digits does not affect parsing.
Exponential patterns may not contain grouping separators.

Rounding

DecimalFormat provides rounding modes defined in RoundingMode for formatting. By default, it uses RoundingMode.HALF_EVEN.

Digits

For formatting, DecimalFormat uses the ten consecutive characters starting with the localized zero digit defined in the DecimalFormatSymbols object as digits. For parsing, these digits as well as all Unicode decimal digits, as defined by Character#digit, are recognized.

Special Values

NaN is formatted as a string, which typically has a single character \uFFFD. This string is determined by the DecimalFormatSymbols object. This is the only value for which the prefixes and suffixes are not used.

Infinity is formatted as a string, which typically has a single character \u221E, with the positive or negative prefixes and suffixes applied. The infinity string is determined by the DecimalFormatSymbols object.

Negative zero ("-0") parses to

BigDecimal(0) if isParseBigDecimal() is true,
Long(0) if isParseBigDecimal() is false and isParseIntegerOnly() is true,
Double(-0.0) if both isParseBigDecimal() and isParseIntegerOnly() are false.

Synchronization

Decimal 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.

Example


 <strong>// Print out a number using the localized number, integer, currency,
 // and percent format for each locale</strong>
 Locale[] locales = NumberFormat.getAvailableLocales();
 double myNumber = -1234.56;
 NumberFormat form;
 for (int j = 0; j < 4; ++j) {
     System.out.println("FORMAT");
     for (int i = 0; i < locales.length; ++i) {
         if (locales[i].getCountry().length() == 0) {
            continue; // Skip language-only locales
         }
         System.out.print(locales[i].getDisplayName());
         switch (j) {
         case 0:
             form = NumberFormat.getInstance(locales[i]); break;
         case 1:
             form = NumberFormat.getIntegerInstance(locales[i]); break;
         case 2:
             form = NumberFormat.getCurrencyInstance(locales[i]); break;
         default:
             form = NumberFormat.getPercentInstance(locales[i]); break;
         }
         if (form instanceof DecimalFormat) {
             System.out.print(": " + ((DecimalFormat) form).toPattern());
         }
         System.out.print(" -> " + form.format(myNumber));
         try {
             System.out.println(" -> " + form.parse(form.format(myNumber)));
         } catch (ParseException e) {}
     }
 }

另请参阅:: Java Tutorial, NumberFormat, DecimalFormatSymbols, ParsePosition, 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
`DecimalFormat()`	Creates a DecimalFormat using the default pattern and symbols for the default `FORMAT` locale.
`DecimalFormat(String pattern)`	Creates a DecimalFormat using the given pattern and the symbols for the default `FORMAT` locale.
`DecimalFormat(String pattern, DecimalFormatSymbols symbols)`	Creates a DecimalFormat using the given pattern and symbols.

方法概要

所有方法实例方法具体方法
限定符和类型	方法	说明
`void`	`applyLocalizedPattern(String pattern)`	Apply the given pattern to this Format object.
`void`	`applyPattern(String pattern)`	Apply the given pattern to this Format object.
`Object`	`clone()`	Standard override; no change in semantics.
`boolean`	`equals(Object obj)`	Overrides equals
`StringBuffer`	`format(double number, StringBuffer result, FieldPosition fieldPosition)`	Formats a double to produce a string.
`StringBuffer`	`format(long number, StringBuffer result, FieldPosition fieldPosition)`	Format a long to produce a string.
`StringBuffer`	`format(Object number, StringBuffer toAppendTo, FieldPosition pos)`	Formats a number and appends the resulting text to the given string buffer.
`AttributedCharacterIterator`	`formatToCharacterIterator(Object obj)`	Formats an Object producing an `AttributedCharacterIterator`.
`Currency`	`getCurrency()`	Gets the currency used by this decimal format when formatting currency values.
`DecimalFormatSymbols`	`getDecimalFormatSymbols()`	Returns a copy of the decimal format symbols, which is generally not changed by the programmer or user.
`int`	`getGroupingSize()`	Return the grouping size.
`int`	`getMaximumFractionDigits()`	Gets the maximum number of digits allowed in the fraction portion of a number.
`int`	`getMaximumIntegerDigits()`	Gets the maximum number of digits allowed in the integer portion of a number.
`int`	`getMinimumFractionDigits()`	Gets the minimum number of digits allowed in the fraction portion of a number.
`int`	`getMinimumIntegerDigits()`	Gets the minimum number of digits allowed in the integer portion of a number.
`int`	`getMultiplier()`	Gets the multiplier for use in percent, per mille, and similar formats.
`String`	`getNegativePrefix()`	Get the negative prefix.
`String`	`getNegativeSuffix()`	Get the negative suffix.
`String`	`getPositivePrefix()`	Get the positive prefix.
`String`	`getPositiveSuffix()`	Get the positive suffix.
`RoundingMode`	`getRoundingMode()`	Gets the `RoundingMode` used in this DecimalFormat.
`int`	`hashCode()`	Overrides hashCode
`boolean`	`isDecimalSeparatorAlwaysShown()`	Allows you to get the behavior of the decimal separator with integers.
`boolean`	`isParseBigDecimal()`	Returns whether the `parse(java.lang.String,java.text.ParsePosition)` method returns `BigDecimal`.
`Number`	`parse(String text, 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`	`setDecimalFormatSymbols(DecimalFormatSymbols newSymbols)`	Sets the decimal format symbols, which is generally not changed by the programmer or user.
`void`	`setDecimalSeparatorAlwaysShown(boolean newValue)`	Allows you to set the behavior of the decimal separator with integers.
`void`	`setGroupingSize(int newValue)`	Set the grouping size.
`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`	`setMultiplier(int newValue)`	Sets the multiplier for use in percent, per mille, and similar formats.
`void`	`setNegativePrefix(String newValue)`	Set the negative prefix.
`void`	`setNegativeSuffix(String newValue)`	Set the negative suffix.
`void`	`setParseBigDecimal(boolean newValue)`	Sets whether the `parse(java.lang.String,java.text.ParsePosition)` method returns `BigDecimal`.
`void`	`setPositivePrefix(String newValue)`	Set the positive prefix.
`void`	`setPositiveSuffix(String newValue)`	Set the positive suffix.
`void`	`setRoundingMode(RoundingMode roundingMode)`	Sets the `RoundingMode` used in this DecimalFormat.
`String`	`toLocalizedPattern()`	Synthesizes a localized pattern string that represents the current state of this Format object.
`String`	`toPattern()`	Synthesizes a pattern string that represents the current state of this Format object.

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

从类继承的方法 java.text.NumberFormat
format, format, getAvailableLocales, getCurrencyInstance, getCurrencyInstance, getInstance, getInstance, getIntegerInstance, getIntegerInstance, getNumberInstance, getNumberInstance, getPercentInstance, getPercentInstance, isGroupingUsed, isParseIntegerOnly, parse, parseObject, setParseIntegerOnly

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
  - DecimalFormat
```
public DecimalFormat()
```
    Creates a DecimalFormat using the default pattern and symbols for the default FORMAT locale. This is a convenient way to obtain a DecimalFormat when internationalization is not the main concern.
    To obtain standard formats for a given locale, use the factory methods on NumberFormat such as getNumberInstance. These factories will return the most appropriate sub-class of NumberFormat for a given locale.
    
    另请参阅:
    
    NumberFormat.getInstance(), NumberFormat.getNumberInstance(), NumberFormat.getCurrencyInstance(), NumberFormat.getPercentInstance()
  - DecimalFormat
```
public DecimalFormat(String pattern)
```
    Creates a DecimalFormat using the given pattern and the symbols for the default FORMAT locale. This is a convenient way to obtain a DecimalFormat when internationalization is not the main concern.
    To obtain standard formats for a given locale, use the factory methods on NumberFormat such as getNumberInstance. These factories will return the most appropriate sub-class of NumberFormat for a given locale.
    
    参数:
    
    pattern - a non-localized pattern string.
    
    抛出:
    
    NullPointerException - if pattern is null
    
    IllegalArgumentException - if the given pattern is invalid.
    
    另请参阅:
    
    NumberFormat.getInstance(), NumberFormat.getNumberInstance(), NumberFormat.getCurrencyInstance(), NumberFormat.getPercentInstance()
  - DecimalFormat
```
public DecimalFormat(String pattern,
                     DecimalFormatSymbols symbols)
```
    Creates a DecimalFormat using the given pattern and symbols. Use this constructor when you need to completely customize the behavior of the format.
    To obtain standard formats for a given locale, use the factory methods on NumberFormat such as getInstance or getCurrencyInstance. If you need only minor adjustments to a standard format, you can modify the format returned by a NumberFormat factory method.
    
    参数:
    
    pattern - a non-localized pattern string
    
    symbols - the set of symbols to be used
    
    抛出:
    
    NullPointerException - if any of the given arguments is null
    
    IllegalArgumentException - if the given pattern is invalid
    
    另请参阅:
    
    NumberFormat.getInstance(), NumberFormat.getNumberInstance(), NumberFormat.getCurrencyInstance(), NumberFormat.getPercentInstance(), DecimalFormatSymbols
- 方法详细资料
  - format
```
public final StringBuffer format(Object number,
                                 StringBuffer toAppendTo,
                                 FieldPosition pos)
```
    Formats a number and appends the resulting text to the given string buffer. The number can be of any subclass of Number.
    This implementation uses the maximum precision permitted.
    
    覆盖:
    
    format 在类中 NumberFormat
    
    参数:
    
    number - the number to format
    
    toAppendTo - the StringBuffer to which the formatted text is to be appended
    
    pos - On input: an alignment field, if desired. On output: the offsets of the alignment field.
    
    返回:
    
    the value passed in as toAppendTo
    
    抛出:
    
    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.UNNECESSARY
    
    另请参阅:
    
    FieldPosition
  - format
```
public StringBuffer format(double number,
                           StringBuffer result,
                           FieldPosition fieldPosition)
```
    Formats a double to produce a string.
    
    指定者:
    
    format 在类中 NumberFormat
    
    参数:
    
    number - The double to format
    
    result - where the text is to be appended
    
    fieldPosition - On input: an alignment field, if desired. On output: the offsets of the alignment field.
    
    返回:
    
    The formatted number string
    
    抛出:
    
    ArithmeticException - if rounding is needed with rounding mode being set to RoundingMode.UNNECESSARY
    
    另请参阅:
    
    FieldPosition
  - format
```
public StringBuffer format(long number,
                           StringBuffer result,
                           FieldPosition fieldPosition)
```
    Format a long to produce a string.
    
    指定者:
    
    format 在类中 NumberFormat
    
    参数:
    
    number - The long to format
    
    result - where the text is to be appended
    
    fieldPosition - On input: an alignment field, if desired. On output: the offsets of the alignment field.
    
    返回:
    
    The formatted number string
    
    抛出:
    
    ArithmeticException - if rounding is needed with rounding mode being set to RoundingMode.UNNECESSARY
    
    另请参阅:
    
    FieldPosition
  - formatToCharacterIterator
```
public AttributedCharacterIterator formatToCharacterIterator(Object obj)
```
    Formats an Object producing an AttributedCharacterIterator. You can use the returned AttributedCharacterIterator to build the resulting String, as well as to determine information about the resulting String.
    Each attribute key of the AttributedCharacterIterator will be of type NumberFormat.Field, with the attribute value being the same as the attribute key.
    
    覆盖:
    
    formatToCharacterIterator 在类中 Format
    
    参数:
    
    obj - The object to format
    
    返回:
    
    AttributedCharacterIterator describing the formatted value.
    
    抛出:
    
    NullPointerException - if obj is null.
    
    IllegalArgumentException - when the Format cannot format the given object.
    
    ArithmeticException - if rounding is needed with rounding mode being set to RoundingMode.UNNECESSARY
    
    从以下版本开始:
    
    1.4
  - parse
```
public Number parse(String text,
                    ParsePosition pos)
```
    Parses text from a string to produce a 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.
    The subclass returned depends on the value of isParseBigDecimal() as well as on the string being parsed.
    - If isParseBigDecimal() is false (the default), most integer values are returned as Long objects, no matter how they are written: "17" and "17.000" both parse to Long(17). Values that cannot fit into a Long are returned as Doubles. This includes values with a fractional part, infinite values, NaN, and the value -0.0. DecimalFormat does not decide whether to return a Double or a Long based on the presence of a decimal separator in the source string. Doing so would prevent integers that overflow the mantissa of a double, such as "-9,223,372,036,854,775,808.00", from being parsed accurately.
      Callers may use the Number methods doubleValue, longValue, etc., to obtain the type they want.
    - If isParseBigDecimal() is true, values are returned as BigDecimal objects. The values are the ones constructed by BigDecimal(String) for corresponding strings in locale-independent format. The special cases negative and positive infinity and NaN are returned as Double instances holding the values of the corresponding Double constants.
    DecimalFormat parses all Unicode characters that represent decimal digits, as defined by Character.digit(). In addition, DecimalFormat also recognizes as digits the ten consecutive characters starting with the localized zero digit defined in the DecimalFormatSymbols object.
    指定者:
    
    parse 在类中 NumberFormat
    
    参数:
    
    text - the string to be parsed
    
    pos - A ParsePosition object with index and error index information as described above.
    
    返回:
    
    the parsed value, or null if the parse fails
    
    抛出:
    
    NullPointerException - if text or pos is null.
    
    另请参阅:
    
    NumberFormat.isParseIntegerOnly(), Format.parseObject(java.lang.String, java.text.ParsePosition)
  - getDecimalFormatSymbols
```
public DecimalFormatSymbols getDecimalFormatSymbols()
```
    Returns a copy of the decimal format symbols, which is generally not changed by the programmer or user.
    
    返回:
    
    a copy of the desired DecimalFormatSymbols
    
    另请参阅:
    
    DecimalFormatSymbols
  - setDecimalFormatSymbols
```
public void setDecimalFormatSymbols(DecimalFormatSymbols newSymbols)
```
    Sets the decimal format symbols, which is generally not changed by the programmer or user.
    
    参数:
    
    newSymbols - desired DecimalFormatSymbols
    
    另请参阅:
    
    DecimalFormatSymbols
  - getPositivePrefix
```
public String getPositivePrefix()
```
    Get the positive prefix.
    Examples: +123, $123, sFr123
    
    返回:
    
    the positive prefix
  - setPositivePrefix
```
public void setPositivePrefix(String newValue)
```
    Set the positive prefix.
    Examples: +123, $123, sFr123
    
    参数:
    
    newValue - the new positive prefix
  - getNegativePrefix
```
public String getNegativePrefix()
```
    Get the negative prefix.
    Examples: -123, ($123) (with negative suffix), sFr-123
    
    返回:
    
    the negative prefix
  - setNegativePrefix
```
public void setNegativePrefix(String newValue)
```
    Set the negative prefix.
    Examples: -123, ($123) (with negative suffix), sFr-123
    
    参数:
    
    newValue - the new negative prefix
  - getPositiveSuffix
```
public String getPositiveSuffix()
```
    Get the positive suffix.
    Example: 123%
    
    返回:
    
    the positive suffix
  - setPositiveSuffix
```
public void setPositiveSuffix(String newValue)
```
    Set the positive suffix.
    Example: 123%
    
    参数:
    
    newValue - the new positive suffix
  - getNegativeSuffix
```
public String getNegativeSuffix()
```
    Get the negative suffix.
    Examples: -123%, ($123) (with positive suffixes)
    
    返回:
    
    the negative suffix
  - setNegativeSuffix
```
public void setNegativeSuffix(String newValue)
```
    Set the negative suffix.
    Examples: 123%
    
    参数:
    
    newValue - the new negative suffix
  - getMultiplier
```
public int getMultiplier()
```
    Gets the multiplier for use in percent, per mille, and similar formats.
    
    返回:
    
    the multiplier
    
    另请参阅:
    
    setMultiplier(int)
  - setMultiplier
```
public void setMultiplier(int newValue)
```
    Sets the multiplier for use in percent, per mille, and similar formats. For a percent format, set the multiplier to 100 and the suffixes to have '%' (for Arabic, use the Arabic percent sign). For a per mille format, set the multiplier to 1000 and the suffixes to have '\u2030'.
    Example: with multiplier 100, 1.23 is formatted as "123", and "123" is parsed into 1.23.
    
    参数:
    
    newValue - the new multiplier
    
    另请参阅:
    
    getMultiplier()
  - setGroupingUsed
```
public void setGroupingUsed(boolean newValue)
```
    Set whether or not grouping will be used in this format.
    
    覆盖:
    
    setGroupingUsed 在类中 NumberFormat
    
    参数:
    
    newValue - true if grouping is used; false otherwise
    
    另请参阅:
    
    NumberFormat.isGroupingUsed()
  - getGroupingSize
```
public int getGroupingSize()
```
    Return the grouping size. Grouping size is the number of digits between grouping separators in the integer portion of a number. For example, in the number "123,456.78", the grouping size is 3.
    
    返回:
    
    the grouping size
    
    另请参阅:
    
    setGroupingSize(int), NumberFormat.isGroupingUsed(), DecimalFormatSymbols.getGroupingSeparator()
  - setGroupingSize
```
public void setGroupingSize(int newValue)
```
    Set the grouping size. Grouping size is the number of digits between grouping separators in the integer portion of a number. For example, in the number "123,456.78", the grouping size is 3.
    The value passed in is converted to a byte, which may lose information.
    
    参数:
    
    newValue - the new grouping size
    
    另请参阅:
    
    getGroupingSize(), NumberFormat.setGroupingUsed(boolean), DecimalFormatSymbols.setGroupingSeparator(char)
  - isDecimalSeparatorAlwaysShown
```
public boolean isDecimalSeparatorAlwaysShown()
```
    Allows you to get the behavior of the decimal separator with integers. (The decimal separator will always appear with decimals.)
    Example: Decimal ON: 12345 → 12345.; OFF: 12345 → 12345
    
    返回:
    
    true if the decimal separator is always shown; false otherwise
  - setDecimalSeparatorAlwaysShown
```
public void setDecimalSeparatorAlwaysShown(boolean newValue)
```
    Allows you to set the behavior of the decimal separator with integers. (The decimal separator will always appear with decimals.)
    Example: Decimal ON: 12345 → 12345.; OFF: 12345 → 12345
    
    参数:
    
    newValue - true if the decimal separator is always shown; false otherwise
  - isParseBigDecimal
```
public boolean isParseBigDecimal()
```
    Returns whether the parse(java.lang.String,java.text.ParsePosition) method returns BigDecimal. The default value is false.
    
    返回:
    
    true if the parse method returns BigDecimal; false otherwise
    
    从以下版本开始:
    
    1.5
    
    另请参阅:
    
    setParseBigDecimal(boolean)
  - setParseBigDecimal
```
public void setParseBigDecimal(boolean newValue)
```
    Sets whether the parse(java.lang.String,java.text.ParsePosition) method returns BigDecimal.
    
    参数:
    
    newValue - true if the parse method returns BigDecimal; false otherwise
    
    从以下版本开始:
    
    1.5
    
    另请参阅:
    
    isParseBigDecimal()
  - clone
```
public Object clone()
```
    Standard override; no change in semantics.
    
    覆盖:
    
    clone 在类中 NumberFormat
    
    返回:
    
    a clone of this instance.
    
    另请参阅:
    
    Cloneable
  - equals
```
public boolean equals(Object obj)
```
    Overrides equals
    
    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
  - hashCode
```
public int hashCode()
```
    Overrides hashCode
    
    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)
  - toPattern
```
public String toPattern()
```
    Synthesizes a pattern string that represents the current state of this Format object.
    
    返回:
    
    a pattern string
    
    另请参阅:
    
    applyPattern(java.lang.String)
  - toLocalizedPattern
```
public String toLocalizedPattern()
```
    Synthesizes a localized pattern string that represents the current state of this Format object.
    
    返回:
    
    a localized pattern string
    
    另请参阅:
    
    applyPattern(java.lang.String)
  - applyPattern
```
public void applyPattern(String pattern)
```
    Apply the given pattern to this Format object. A pattern is a short-hand specification for the various formatting properties. These properties can also be changed individually through the various setter methods.
    There is no limit to integer digits set by this routine, since that is the typical end-user desire; use setMaximumInteger if you want to set a real value. For negative numbers, use a second pattern, separated by a semicolon
    Example "#,#00.0#" → 1,234.56
    This means a minimum of 2 integer digits, 1 fraction digit, and a maximum of 2 fraction digits.
    Example: "#,#00.0#;(#,#00.0#)" for negatives in parentheses.
    In negative patterns, the minimum and maximum counts are ignored; these are presumed to be set in the positive pattern.
    
    参数:
    
    pattern - a new pattern
    
    抛出:
    
    NullPointerException - if pattern is null
    
    IllegalArgumentException - if the given pattern is invalid.
  - applyLocalizedPattern
```
public void applyLocalizedPattern(String pattern)
```
    Apply the given pattern to this Format object. The pattern is assumed to be in a localized notation. A pattern is a short-hand specification for the various formatting properties. These properties can also be changed individually through the various setter methods.
    There is no limit to integer digits set by this routine, since that is the typical end-user desire; use setMaximumInteger if you want to set a real value. For negative numbers, use a second pattern, separated by a semicolon
    Example "#,#00.0#" → 1,234.56
    This means a minimum of 2 integer digits, 1 fraction digit, and a maximum of 2 fraction digits.
    Example: "#,#00.0#;(#,#00.0#)" for negatives in parentheses.
    In negative patterns, the minimum and maximum counts are ignored; these are presumed to be set in the positive pattern.
    
    参数:
    
    pattern - a new pattern
    
    抛出:
    
    NullPointerException - if pattern is null
    
    IllegalArgumentException - if the given pattern is invalid.
  - setMaximumIntegerDigits
```
public void setMaximumIntegerDigits(int newValue)
```
    Sets the maximum number of digits allowed in the integer portion of a number. For formatting numbers other than BigInteger and BigDecimal objects, the lower of newValue and 309 is used. Negative input values are replaced with 0.
    
    覆盖:
    
    setMaximumIntegerDigits 在类中 NumberFormat
    
    参数:
    
    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.
    
    另请参阅:
    
    NumberFormat.setMaximumIntegerDigits(int)
  - setMinimumIntegerDigits
```
public void setMinimumIntegerDigits(int newValue)
```
    Sets the minimum number of digits allowed in the integer portion of a number. For formatting numbers other than BigInteger and BigDecimal objects, the lower of newValue and 309 is used. Negative input values are replaced with 0.
    
    覆盖:
    
    setMinimumIntegerDigits 在类中 NumberFormat
    
    参数:
    
    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.
    
    另请参阅:
    
    NumberFormat.setMinimumIntegerDigits(int)
  - setMaximumFractionDigits
```
public void setMaximumFractionDigits(int newValue)
```
    Sets the maximum number of digits allowed in the fraction portion of a number. For formatting numbers other than BigInteger and BigDecimal objects, the lower of newValue and 340 is used. Negative input values are replaced with 0.
    
    覆盖:
    
    setMaximumFractionDigits 在类中 NumberFormat
    
    参数:
    
    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.
    
    另请参阅:
    
    NumberFormat.setMaximumFractionDigits(int)
  - setMinimumFractionDigits
```
public void setMinimumFractionDigits(int newValue)
```
    Sets the minimum number of digits allowed in the fraction portion of a number. For formatting numbers other than BigInteger and BigDecimal objects, the lower of newValue and 340 is used. Negative input values are replaced with 0.
    
    覆盖:
    
    setMinimumFractionDigits 在类中 NumberFormat
    
    参数:
    
    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.
    
    另请参阅:
    
    NumberFormat.setMinimumFractionDigits(int)
  - getMaximumIntegerDigits
```
public int getMaximumIntegerDigits()
```
    Gets the maximum number of digits allowed in the integer portion of a number. For formatting numbers other than BigInteger and BigDecimal objects, the lower of the return value and 309 is used.
    
    覆盖:
    
    getMaximumIntegerDigits 在类中 NumberFormat
    
    返回:
    
    the maximum number of digits
    
    另请参阅:
    
    setMaximumIntegerDigits(int)
  - getMinimumIntegerDigits
```
public int getMinimumIntegerDigits()
```
    Gets the minimum number of digits allowed in the integer portion of a number. For formatting numbers other than BigInteger and BigDecimal objects, the lower of the return value and 309 is used.
    
    覆盖:
    
    getMinimumIntegerDigits 在类中 NumberFormat
    
    返回:
    
    the minimum number of digits
    
    另请参阅:
    
    setMinimumIntegerDigits(int)
  - getMaximumFractionDigits
```
public int getMaximumFractionDigits()
```
    Gets the maximum number of digits allowed in the fraction portion of a number. For formatting numbers other than BigInteger and BigDecimal objects, the lower of the return value and 340 is used.
    
    覆盖:
    
    getMaximumFractionDigits 在类中 NumberFormat
    
    返回:
    
    the maximum number of digits.
    
    另请参阅:
    
    setMaximumFractionDigits(int)
  - getMinimumFractionDigits
```
public int getMinimumFractionDigits()
```
    Gets the minimum number of digits allowed in the fraction portion of a number. For formatting numbers other than BigInteger and BigDecimal objects, the lower of the return value and 340 is used.
    
    覆盖:
    
    getMinimumFractionDigits 在类中 NumberFormat
    
    返回:
    
    the minimum number of digits
    
    另请参阅:
    
    setMinimumFractionDigits(int)
  - getCurrency
```
public Currency getCurrency()
```
    Gets the currency used by this decimal format when formatting currency values. The currency is obtained by calling DecimalFormatSymbols#getCurrency on this number format's symbols.
    
    覆盖:
    
    getCurrency 在类中 NumberFormat
    
    返回:
    
    the currency used by this decimal format, or null
    
    从以下版本开始:
    
    1.4
  - setCurrency
```
public void setCurrency(Currency currency)
```
    Sets the currency used by this number format when formatting currency values. This does not update the minimum or maximum number of fraction digits used by the number format. The currency is set by calling DecimalFormatSymbols#setCurrency on this number format's symbols.
    
    覆盖:
    
    setCurrency 在类中 NumberFormat
    
    参数:
    
    currency - the new currency to be used by this decimal format
    
    抛出:
    
    NullPointerException - if currency is null
    
    从以下版本开始:
    
    1.4
  - getRoundingMode
```
public RoundingMode getRoundingMode()
```
    Gets the RoundingMode used in this DecimalFormat.
    
    覆盖:
    
    getRoundingMode 在类中 NumberFormat
    
    返回:
    
    The RoundingMode used for this DecimalFormat.
    
    从以下版本开始:
    
    1.6
    
    另请参阅:
    
    setRoundingMode(RoundingMode)
  - setRoundingMode
```
public void setRoundingMode(RoundingMode roundingMode)
```
    Sets the RoundingMode used in this DecimalFormat.
    
    覆盖:
    
    setRoundingMode 在类中 NumberFormat
    
    参数:
    
    roundingMode - The RoundingMode to be used
    
    抛出:
    
    NullPointerException - if roundingMode is null.
    
    从以下版本开始:
    
    1.6
    
    另请参阅:
    
    getRoundingMode()

类 DecimalFormat

Patterns

Special Pattern Characters

Scientific Notation

Rounding

Digits

Special Values

Synchronization

Example

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

DecimalFormat

DecimalFormat

DecimalFormat

方法详细资料

format

format

format

formatToCharacterIterator

parse

getDecimalFormatSymbols

setDecimalFormatSymbols

getPositivePrefix

setPositivePrefix

getNegativePrefix

setNegativePrefix

getPositiveSuffix

setPositiveSuffix

getNegativeSuffix

setNegativeSuffix

getMultiplier

setMultiplier

setGroupingUsed

getGroupingSize

setGroupingSize

isDecimalSeparatorAlwaysShown

setDecimalSeparatorAlwaysShown

isParseBigDecimal

setParseBigDecimal

clone

equals

hashCode

toPattern

toLocalizedPattern

applyPattern

applyLocalizedPattern

setMaximumIntegerDigits

setMinimumIntegerDigits

setMaximumFractionDigits

setMinimumFractionDigits

getMaximumIntegerDigits

getMinimumIntegerDigits

getMaximumFractionDigits

getMinimumFractionDigits

getCurrency

setCurrency

getRoundingMode

setRoundingMode