NumberFormatter (Java SE 17 & JDK 17)
Description: declaration: module: java.desktop, package: javax.swing.text, class: NumberFormatter
Keywords: javax.swing.text.NumberFormatter class

Module java.desktop
Package javax.swing.text

# Class NumberFormatter

java.lang.Object
javax.swing.JFormattedTextField.AbstractFormatter
javax.swing.text.DefaultFormatter
javax.swing.text.InternationalFormatter
javax.swing.text.NumberFormatter

All Implemented Interfaces:
  `Serializable`, `Cloneable`

public class NumberFormatter extends InternationalFormatter
`NumberFormatter` subclasses `InternationalFormatter` adding special behavior for numbers. Among the specializations are (these are only used if the `NumberFormatter` does not display invalid numbers, for example, `setAllowsInvalid(false)`):

- Pressing +/- (- is determined from the `DecimalFormatSymbols` associated with the `DecimalFormat`) in any field but the exponent field will attempt to change the sign of the number to positive/negative.
- Pressing +/- (- is determined from the `DecimalFormatSymbols` associated with the `DecimalFormat`) in the exponent field will attempt to change the sign of the exponent to positive/negative.

If you are displaying scientific numbers, you may wish to turn on overwrite mode, `setOverwriteMode(true)`. For example:

     DecimalFormat decimalFormat = new DecimalFormat("0.000E0");
     NumberFormatter textFormatter = new NumberFormatter(decimalFormat);
     textFormatter.setOverwriteMode(true);
     textFormatter.setAllowsInvalid(false);

If you are going to allow the user to enter decimal values, you should either force the DecimalFormat to contain at least one decimal (`#.0###`), or allow the value to be invalid `setAllowsInvalid(true)`. Otherwise users may not be able to input decimal values.

`NumberFormatter` provides slightly different behavior to `stringToValue` than that of its superclass. If you have specified a Class for values, `DefaultFormatter.setValueClass(java.lang.Class<?>)`, that is one of of `Integer`, `Long`, `Float`, `Double`, `Byte` or `Short` and the Format's `parseObject` returns an instance of `Number`, the corresponding instance of the value class will be created using the constructor appropriate for the primitive type the value class represents. For example: `setValueClass(Integer.class)` will cause the resulting value to be created via `Integer.valueOf(((Number)formatter.parseObject(string)).intValue())`. This is typically useful if you wish to set a min/max value as the various `Number` implementations are generally not comparable to each other. This is also useful if for some reason you need a specific `Number` implementation for your values.

Warning: Serialized objects of this class will not be compatible with future Swing releases. The current serialization support is appropriate for short term storage or RMI between applications running the same version of Swing. As of 1.4, support for long term storage of all JavaBeans has been added to the `java.beans` package. Please see `XMLEncoder`.

Since:
  1.4

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `NumberFormatter()`
  Creates a `NumberFormatter` with the a default `NumberFormat` instance obtained from `NumberFormat.getNumberInstance()`.
  `NumberFormatter(NumberFormat format)`
  Creates a NumberFormatter with the specified Format instance.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `void`
  `setFormat(Format format)`
  Sets the format that dictates the legal values that can be edited and displayed.

  ### Methods declared in class javax.swing.text.InternationalFormatter

  `clone, getActions, getFields, getFormat, getMaximum, getMinimum, install, setMaximum, setMinimum, stringToValue, valueToString`

  ### Methods declared in class javax.swing.text.DefaultFormatter

  `getAllowsInvalid, getCommitsOnValidEdit, getDocumentFilter, getNavigationFilter, getOverwriteMode, getValueClass, setAllowsInvalid, setCommitsOnValidEdit, setOverwriteMode, setValueClass`

  ### Methods declared in class javax.swing.JFormattedTextField.AbstractFormatter

  `getFormattedTextField, invalidEdit, setEditValid, uninstall`

  ### Methods declared in class java.lang.Object

  `equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- ## Constructor Details

  - ### NumberFormatter

    public NumberFormatter()
    Creates a `NumberFormatter` with the a default `NumberFormat` instance obtained from `NumberFormat.getNumberInstance()`.

  - ### NumberFormatter

    public NumberFormatter(NumberFormat format)
    Creates a NumberFormatter with the specified Format instance.
    Parameters:
      `format` - Format used to dictate legal values

- ## Method Details

  - ### setFormat

    public void setFormat(Format format)
    Sets the format that dictates the legal values that can be edited and displayed.

    If you have used the nullary constructor the value of this property will be determined for the current locale by way of the `NumberFormat.getNumberInstance()` method.

    Overrides:
      `setFormat` in class `InternationalFormatter`
    Parameters:
      `format` - NumberFormat instance used to dictate legal values