NumberFormat Class

Definition

[Android.Runtime.Register("java/text/NumberFormat", DoNotGenerateAcw=true)]
public abstract class NumberFormat : Java.Text._Format

[<Android.Runtime.Register("java/text/NumberFormat", DoNotGenerateAcw=true)>]
type NumberFormat = class
    inherit _Format

Inheritance

Object

Object

_Format

NumberFormat

Derived

Java.Text.ChoiceFormat

Java.Text.DecimalFormat

Attributes

RegisterAttribute

Remarks

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: <blockquote>

{@code
            myString = NumberFormat.getInstance().format(myNumber);
            }

</blockquote> 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. <blockquote>

{@code
            NumberFormat nf = NumberFormat.getInstance();
            for (int i = 0; i < myNumber.length; ++i) {
                output.println(nf.format(myNumber[i]) + "; ");
            }
            }

</blockquote> To format a number for a different Locale, specify it in the call to getInstance. <blockquote>

{@code
            NumberFormat nf = NumberFormat.getInstance(Locale.FRENCH);
            }

</blockquote>

If the locale contains "nu" (numbers) Unicode extensions, the decimal digits, and/or the country used for formatting are overridden.

You can also use a NumberFormat to parse numbers: <blockquote>

{@code
            myNumber = nf.parse(myString);
            }

</blockquote> Use 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. Use getCompactNumberInstance to get the compact number format to format a number in shorter form. For example, 2000 can be formatted as "2K" in java.util.Locale#US US locale. 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 or CompactNumberFormat depending on the factory method used. 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" &rarr; 3456 (and leaves the parse position just after index 6) if false, "3456.78" &rarr; 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 &rarr; "3,456." if false, 3456.00 &rarr; "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: <ul> <li> progressively parse through pieces of a string <li> align the decimal point and other areas </ul> For example, you can align numbers in two ways: <ol> <li> If you are using a monospaced font with spacing for alignment, you can pass the 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.

<li> If you are using proportional fonts, instead of padding with spaces, measure the width of the string in pixels from the start to 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. </ol>

<h2>"synchronization">Synchronization</h2>

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.

Added in 1.1.

Java documentation for java.text.NumberFormat.

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

Fields

Properties

Methods

Explicit Interface Implementations

Extension Methods

Applies to