org.apache.commons.beanutils.converters

## Class BooleanConverter

- java.lang.Object
- - org.apache.commons.beanutils.converters.AbstractConverter
  - - org.apache.commons.beanutils.converters.BooleanConverter

- All Implemented Interfaces:
    Converter

      public final class BooleanConverter
      extends AbstractConverter

  `Converter` implementation that handles conversion to and from Boolean objects. `Converter` implementation that handles conversion to and from java.lang.Boolean objects.

  Can be configured to either return a default value or throw a `ConversionException` if a conversion error occurs.

  By default any object whose string representation is one of the values {"yes", "y", "true", "on", "1"} is converted to Boolean.TRUE, and string representations {"no", "n", "false", "off", "0"} are converted to Boolean.FALSE. The recognized true/false strings can be changed by:

        String[] trueStrings = {"oui", "o", "1"};
        String[] falseStrings = {"non", "n", "0"};
        Converter bc = new BooleanConverter(trueStrings, falseStrings);
        ConvertUtils.register(bc, Boolean.class);
        ConvertUtils.register(bc, Boolean.TYPE);

  In addition, it is recommended that the BooleanArrayConverter also be modified to recognise the same set of values:

         Converter bac = new BooleanArrayConverter(bc, BooleanArrayConverter.NO_DEFAULT);
         ConvertUtils.register(bac, bac.MODEL);

  Case is ignored when converting values to true or false.

  Since:
    1.3
  Version:
    $Id$

- - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `static Object` | `NO_DEFAULT` Deprecated. Use constructors without default value.

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `BooleanConverter()` Create a `Converter` that will throw a `ConversionException` if a conversion error occurs, ie the string value being converted is not one of the known true strings, nor one of the known false strings.
    `BooleanConverter(Object defaultValue)` Create a `Converter` that will return the specified default value if a conversion error occurs, ie the string value being converted is not one of the known true strings, nor one of the known false strings.
    `BooleanConverter(String[] trueStrings, String[] falseStrings)` Create a `Converter` that will throw a `ConversionException` if a conversion error occurs, ie the string value being converted is not one of the known true strings, nor one of the known false strings.
    `BooleanConverter(String[] trueStrings, String[] falseStrings, Object defaultValue)` Create a `Converter` that will return the specified default value if a conversion error occurs.

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `protected <T> T` | `convertToType(Class<T> type, Object value)` Convert the specified input object into an output object of the specified type.
    `protected Class<Boolean>` | `getDefaultType()` Return the default type this `Converter` handles.

    - ### Methods inherited from class org.apache.commons.beanutils.converters.AbstractConverter

      `conversionException, convert, convertArray, convertToString, getDefault, handleError, handleMissing, isUseDefault, setDefaultValue, toString`

    - ### Methods inherited from class java.lang.Object

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

- - ### Field Detail

    - #### NO_DEFAULT

          @Deprecated
          public static final Object NO_DEFAULT

      Deprecated. Use constructors without default value.
      This is a special reference that can be passed as the "default object" to the constructor to indicate that no default is desired. Note that the value 'null' cannot be used for this purpose, as the caller may want a null to be returned as the default.

  - ### Constructor Detail

    - #### BooleanConverter

          public BooleanConverter()

      Create a `Converter` that will throw a `ConversionException` if a conversion error occurs, ie the string value being converted is not one of the known true strings, nor one of the known false strings.

    - #### BooleanConverter

          public BooleanConverter(Object defaultValue)

      Create a `Converter` that will return the specified default value if a conversion error occurs, ie the string value being converted is not one of the known true strings, nor one of the known false strings.
      Parameters:
        `defaultValue` - The default value to be returned if the value being converted is not recognized. This value may be null, in which case null will be returned on conversion failure. When non-null, it is expected that this value will be either Boolean.TRUE or Boolean.FALSE. The special value BooleanConverter.NO_DEFAULT can also be passed here, in which case this constructor acts like the no-argument one.

    - #### BooleanConverter

          public BooleanConverter(String[] trueStrings,
                                  String[] falseStrings)

      Create a `Converter` that will throw a `ConversionException` if a conversion error occurs, ie the string value being converted is not one of the known true strings, nor one of the known false strings.

      The provided string arrays are copied, so that changes to the elements of the array after this call is made do not affect this object.

      Parameters:
        `trueStrings` - is the set of strings which should convert to the value Boolean.TRUE. The value null must not be present. Case is ignored.
        `falseStrings` - is the set of strings which should convert to the value Boolean.TRUE. The value null must not be present. Case is ignored.
      Since:
        1.8.0

    - #### BooleanConverter

          public BooleanConverter(String[] trueStrings,
                                  String[] falseStrings,
                                  Object defaultValue)

      Create a `Converter` that will return the specified default value if a conversion error occurs.

      The provided string arrays are copied, so that changes to the elements of the array after this call is made do not affect this object.

      Parameters:
        `trueStrings` - is the set of strings which should convert to the value Boolean.TRUE. The value null must not be present. Case is ignored.
        `falseStrings` - is the set of strings which should convert to the value Boolean.TRUE. The value null must not be present. Case is ignored.
        `defaultValue` - The default value to be returned if the value being converted is not recognized. This value may be null, in which case null will be returned on conversion failure. When non-null, it is expected that this value will be either Boolean.TRUE or Boolean.FALSE. The special value BooleanConverter.NO_DEFAULT can also be passed here, in which case an exception will be thrown on conversion failure.
      Since:
        1.8.0

  - ### Method Detail

    - #### getDefaultType

          protected Class<Boolean> getDefaultType()

      Return the default type this `Converter` handles.
      Specified by:
        `getDefaultType` in class `AbstractConverter`
      Returns:
        The default type this `Converter` handles.
      Since:
        1.8.0

    - #### convertToType

          protected <T> T convertToType(Class<T> type,
                                        Object value)
                                 throws Throwable

      Convert the specified input object into an output object of the specified type.
      Specified by:
        `convertToType` in class `AbstractConverter`
      Type Parameters:
        `T` - Target type of the conversion.
      Parameters:
        `type` - is the type to which this value should be converted. In the case of this BooleanConverter class, this value is ignored.
        `value` - is the input value to be converted. The toString method shall be invoked on this object, and the result compared (ignoring case) against the known "true" and "false" string values.
      Returns:
        Boolean.TRUE if the value was a recognized "true" value, Boolean.FALSE if the value was a recognized "false" value, or the default value if the value was not recognized and the constructor was provided with a default value.
      Throws:
        `Throwable` - if an error occurs converting to the specified type
      Since:
        1.8.0

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