DecimalFormat Class
Definition
Important
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DecimalFormat is a concrete subclass of
NumberFormat that formats decimal numbers.
[Android.Runtime.Register("java/text/DecimalFormat", DoNotGenerateAcw=true)]
public class DecimalFormat : Java.Text.NumberFormat[<Android.Runtime.Register("java/text/DecimalFormat", DoNotGenerateAcw=true)>]
type DecimalFormat = class
inherit NumberFormat- Inheritance
- Attributes
Remarks
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:
<blockquote>
NumberFormat f = NumberFormat.getInstance(loc);
if (f instanceof DecimalFormat) {
((DecimalFormat) f).setDecimalSeparatorAlwaysShown(true);
}
</blockquote>
A DecimalFormat comprises a <em>pattern</em> and a set of <em>symbols</em>. 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.
<h2>Patterns</h2>
DecimalFormat patterns have the following syntax: <blockquote>
<i>Pattern:</i>
<i>PositivePattern</i>
<i>PositivePattern</i> ; <i>NegativePattern</i>
<i>PositivePattern:</i>
<i>Prefix<sub>opt</sub></i> <i>Number</i> <i>Suffix<sub>opt</sub></i>
<i>NegativePattern:</i>
<i>Prefix<sub>opt</sub></i> <i>Number</i> <i>Suffix<sub>opt</sub></i>
<i>Prefix:</i>
any Unicode characters except \uFFFE, \uFFFF, and special characters
<i>Suffix:</i>
any Unicode characters except \uFFFE, \uFFFF, and special characters
<i>Number:</i>
<i>Integer</i> <i>Exponent<sub>opt</sub></i>
<i>Integer</i> . <i>Fraction</i> <i>Exponent<sub>opt</sub></i>
<i>Integer:</i>
<i>MinimumInteger</i>
#
# <i>Integer</i>
# , <i>Integer</i>
<i>MinimumInteger:</i>
0
0 <i>MinimumInteger</i>
0 , <i>MinimumInteger</i>
<i>Fraction:</i>
<i>MinimumFraction<sub>opt</sub></i> <i>OptionalFraction<sub>opt</sub></i>
<i>MinimumFraction:</i>
0 <i>MinimumFraction<sub>opt</sub></i>
<i>OptionalFraction:</i>
# <i>OptionalFraction<sub>opt</sub></i>
<i>Exponent:</i>
E <i>MinimumExponent</i>
<i>MinimumExponent:</i>
0 <i>MinimumExponent<sub>opt</sub></i>
</blockquote>
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 minus sign ('-' U+002D HYPHEN-MINUS) 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, grouping 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 grouping 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 "#,##,###,####" == "######,####" == "##,####,####".
<h3>"special_pattern_character">Special Pattern Characters</h3>
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.
<blockquote> <table class="striped"> <caption style="display:none">Chart showing symbol, location, localized, and meaning.</caption> <thead> <tr> <th scope="col" style="text-align:left">Symbol <th scope="col" style="text-align:left">Location <th scope="col" style="text-align:left">Localized? <th scope="col" style="text-align:left">Meaning </thead> <tbody> <tr style="vertical-align:top"> <th scope="row">0<td>Number <td>Yes <td>Digit <tr style="vertical-align: top"> <th scope="row">#<td>Number <td>Yes <td>Digit, zero shows as absent <tr style="vertical-align:top"> <th scope="row">.<td>Number <td>Yes <td>Decimal separator or monetary decimal separator <tr style="vertical-align: top"> <th scope="row">-<td>Number <td>Yes <td>Minus sign <tr style="vertical-align:top"> <th scope="row">,<td>Number <td>Yes <td>Grouping separator or monetary grouping separator <tr style="vertical-align: top"> <th scope="row">E<td>Number <td>Yes <td>Separates mantissa and exponent in scientific notation. <em>Need not be quoted in prefix or suffix.</em> <tr style="vertical-align:top"> <th scope="row">;<td>Subpattern boundary <td>Yes <td>Separates positive and negative subpatterns <tr style="vertical-align: top"> <th scope="row">%<td>Prefix or suffix <td>Yes <td>Multiply by 100 and show as percentage <tr style="vertical-align:top"> <th scope="row">\u2030<td>Prefix or suffix <td>Yes <td>Multiply by 1000 and show as per mille value <tr style="vertical-align: top"> <th scope="row">¤ (\u00A4) <td>Prefix or suffix <td>No <td>Currency sign, replaced by currency symbol. If doubled, replaced by international currency symbol. If present in a pattern, the monetary decimal/grouping separators are used instead of the decimal/grouping separators. <tr style="vertical-align:top"> <th scope="row">'<td>Prefix or suffix <td>No <td>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". </tbody> </table> </blockquote>
<h3>Scientific Notation</h3>
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 <em>only via a pattern</em>; 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".
<ul> <li>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, <em>not</em> the prefix and suffix from the pattern. This allows patterns such as "0.###E0 m/s".
<li>The minimum and maximum number of integer digits are interpreted together:
<ul> <li>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 <em>engineering notation</em>, 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".
<li>Otherwise, the minimum number of integer digits is achieved by adjusting the exponent. Example: 0.00123 formatted with "00.###E0" yields "12.3E-4". </ul>
<li>The number of significant digits in the mantissa is the sum of the <em>minimum integer</em> and <em>maximum fraction</em> 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.
<li>Exponential patterns may not contain grouping separators. </ul>
<h3>Rounding</h3>
DecimalFormat provides rounding modes defined in java.math.RoundingMode for formatting. By default, it uses java.math.RoundingMode#HALF_EVEN RoundingMode.HALF_EVEN.
<h3>Digits</h3>
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 Character.digit, are recognized.
<h4>Special Values</h4>
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 <ul> <li>BigDecimal(0) if isParseBigDecimal() is true, <li>Long(0) if isParseBigDecimal() is false and isParseIntegerOnly() is true, <li>Double(-0.0) if both isParseBigDecimal() and isParseIntegerOnly() are false. </ul>
<h3>"synchronization">Synchronization</h3>
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.
<h3>Example</h3>
<blockquote>
<strong>{@code
// Print out a number using the localized number, integer, currency,
// and percent format for each locale}</strong>{@code
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) {}
}
}
}
</blockquote>
Added in 1.1.
Java documentation for java.text.DecimalFormat.
Portions of this page are modifications based on work created and shared by the Android Open Source Project and used according to terms described in the Creative Commons 2.5 Attribution License.
Constructors
| DecimalFormat() |
Creates a DecimalFormat using the default pattern and symbols
for the default |
| DecimalFormat(IntPtr, JniHandleOwnership) |
A constructor used when creating managed representations of JNI objects; called by the runtime. |
| DecimalFormat(String) |
Creates a DecimalFormat using the given pattern and the symbols
for the default |
| DecimalFormat(String, DecimalFormatSymbols) |
Creates a DecimalFormat using the given pattern and symbols. |
Fields
| FractionField |
Field constant used to construct a FieldPosition object. (Inherited from NumberFormat) |
| IntegerField |
Field constant used to construct a FieldPosition object. (Inherited from NumberFormat) |
Properties
| Class |
Returns the runtime class of this |
| Currency |
Gets the currency used by this number format when formatting currency values. -or- Sets the currency used by this number format when formatting currency values. (Inherited from NumberFormat) |
| DecimalFormatSymbols |
Returns a copy of the decimal format symbols, which is generally not changed by the programmer or user. -or- Sets the decimal format symbols, which is generally not changed by the programmer or user. |
| DecimalSeparatorAlwaysShown |
Allows you to get the behavior of the decimal separator with integers. -or- Allows you to set the behavior of the decimal separator with integers. |
| GroupingSize |
Return the grouping size. -or- Set the grouping size. |
| GroupingUsed |
Returns true if grouping is used in this format. -or- Set whether or not grouping will be used in this format. (Inherited from NumberFormat) |
| Handle |
The handle to the underlying Android instance. (Inherited from Object) |
| JniIdentityHashCode | (Inherited from Object) |
| JniPeerMembers | |
| MaximumFractionDigits |
Returns the maximum number of digits allowed in the fraction portion of a number. -or- Sets the maximum number of digits allowed in the fraction portion of a number. (Inherited from NumberFormat) |
| MaximumIntegerDigits |
Returns the maximum number of digits allowed in the integer portion of a number. -or- Sets the maximum number of digits allowed in the integer portion of a number. (Inherited from NumberFormat) |
| MinimumFractionDigits |
Returns the minimum number of digits allowed in the fraction portion of a number. -or- Sets the minimum number of digits allowed in the fraction portion of a number. (Inherited from NumberFormat) |
| MinimumIntegerDigits |
Returns the minimum number of digits allowed in the integer portion of a number. -or- Sets the minimum number of digits allowed in the integer portion of a number. (Inherited from NumberFormat) |
| Multiplier |
Gets the multiplier for use in percent, per mille, and similar formats. -or- Sets the multiplier for use in percent, per mille, and similar formats. |
| NegativePrefix |
Get the negative prefix. -or- Set the negative prefix. |
| NegativeSuffix |
Get the negative suffix. -or- Set the negative suffix. |
| ParseBigDecimal |
Returns whether the |
| ParseIntegerOnly |
Returns true if this format will parse numbers as integers only. -or- Sets whether or not numbers should be parsed as integers only. (Inherited from NumberFormat) |
| PeerReference | (Inherited from Object) |
| PositivePrefix |
Get the positive prefix. -or- Set the positive prefix. |
| PositiveSuffix |
Get the positive suffix. -or- Set the positive suffix. |
| RoundingMode |
Gets the |
| ThresholdClass |
This API supports the Mono for Android infrastructure and is not intended to be used directly from your code. |
| ThresholdType |
This API supports the Mono for Android infrastructure and is not intended to be used directly from your code. |
Methods
| ApplyLocalizedPattern(String) |
Apply the given pattern to this Format object. |
| ApplyPattern(String) |
Apply the given pattern to this Format object. |
| Clone() |
Creates and returns a copy of this object. (Inherited from _Format) |
| Dispose() | (Inherited from Object) |
| Dispose(Boolean) | (Inherited from Object) |
| Equals(Object) |
Indicates whether some other object is "equal to" this one. (Inherited from Object) |
| Format(Double) |
Specialization of format. (Inherited from NumberFormat) |
| Format(Double, StringBuffer, FieldPosition) |
Formats a double to produce a string. |
| Format(Int64) |
Specialization of format. (Inherited from NumberFormat) |
| Format(Int64, StringBuffer, FieldPosition) |
Format a long to produce a string. |
| Format(Object) |
Formats an object to produce a string. (Inherited from _Format) |
| Format(Object, StringBuffer, FieldPosition) |
Formats a number and appends the resulting text to the given string buffer. |
| FormatToCharacterIterator(Object) |
Formats an Object producing an |
| GetHashCode() |
Returns a hash code value for the object. (Inherited from Object) |
| JavaFinalize() |
Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. (Inherited from Object) |
| Notify() |
Wakes up a single thread that is waiting on this object's monitor. (Inherited from Object) |
| NotifyAll() |
Wakes up all threads that are waiting on this object's monitor. (Inherited from Object) |
| Parse(String) |
Parses text from the beginning of the given string to produce a number. (Inherited from NumberFormat) |
| Parse(String, ParsePosition) |
Parses text from a string to produce a |
| ParseObject(String) |
Parses text from the beginning of the given string to produce an object. (Inherited from _Format) |
| ParseObject(String, ParsePosition) |
Parses text from a string to produce a |
| SetHandle(IntPtr, JniHandleOwnership) |
Sets the Handle property. (Inherited from Object) |
| ToArray<T>() | (Inherited from Object) |
| ToLocalizedPattern() |
Synthesizes a localized pattern string that represents the current state of this Format object. |
| ToPattern() |
Synthesizes a pattern string that represents the current state of this Format object. |
| ToString() |
Returns a string representation of the object. (Inherited from Object) |
| UnregisterFromRuntime() | (Inherited from Object) |
| Wait() |
Causes the current thread to wait until it is awakened, typically by being <em>notified</em> or <em>interrupted</em>. (Inherited from Object) |
| Wait(Int64) |
Causes the current thread to wait until it is awakened, typically by being <em>notified</em> or <em>interrupted</em>, or until a certain amount of real time has elapsed. (Inherited from Object) |
| Wait(Int64, Int32) |
Causes the current thread to wait until it is awakened, typically by being <em>notified</em> or <em>interrupted</em>, or until a certain amount of real time has elapsed. (Inherited from Object) |
Explicit Interface Implementations
| IJavaPeerable.Disposed() | (Inherited from Object) |
| IJavaPeerable.DisposeUnlessReferenced() | (Inherited from Object) |
| IJavaPeerable.Finalized() | (Inherited from Object) |
| IJavaPeerable.JniManagedPeerState | (Inherited from Object) |
| IJavaPeerable.SetJniIdentityHashCode(Int32) | (Inherited from Object) |
| IJavaPeerable.SetJniManagedPeerState(JniManagedPeerStates) | (Inherited from Object) |
| IJavaPeerable.SetPeerReference(JniObjectReference) | (Inherited from Object) |
Extension Methods
| JavaCast<TResult>(IJavaObject) |
Performs an Android runtime-checked type conversion. |
| JavaCast<TResult>(IJavaObject) | |
| GetJniTypeName(IJavaPeerable) | |