AbstractConverter (Apache Commons BeanUtils 1.11.0 API)

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

All Implemented Interfaces:

Converter

Direct Known Subclasses:

ArrayConverter, BooleanConverter, CharacterConverter, ClassConverter, DateTimeConverter, FileConverter, NumberConverter, StringConverter, URLConverter
```
public abstract class AbstractConverter
extends Object
implements Converter
```
Base Converter implementation that provides the structure for handling conversion to and from a specified type.
This implementation provides the basic structure for converting to/from a specified type optionally using a default value or throwing a ConversionException if a conversion error occurs.
Implementations should provide conversion to the specified type and from the specified type to a String value by implementing the following methods:
- convertToString(value) - convert to a String (default implementation uses the objects toString() method).
- convertToType(Class, value) - convert to the specified type
The default value has to be compliant to the default type of this converter - which is enforced by the generic type parameter. If a conversion is not possible and a default value is set, the converter tries to transform the default value to the requested target type. If this fails, a ConversionException if thrown.
Since:

1.8.0

Constructor Summary

Constructors
Constructor and Description
`AbstractConverter()` Construct a Converter that throws a `ConversionException` if an error occurs.
`AbstractConverter(Object defaultValue)` Construct a Converter that returns a default value if an error occurs.

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method and Description
`protected ConversionException`	`conversionException(Class<?> type, Object value)` Generates a standard conversion exception with a message indicating that the passed in value cannot be converted to the desired target type.
`<T> T`	`convert(Class<T> type, Object value)` Convert the input object into an output object of the specified type.
`protected Object`	`convertArray(Object value)` Return the first element from an Array (or Collection) or the value unchanged if not an Array (or Collection).
`protected String`	`convertToString(Object value)` Convert the input object into a String.
`protected abstract <T> T`	`convertToType(Class<T> type, Object value)` Convert the input object into an output object of the specified type.
`protected Object`	`getDefault(Class<?> type)` Return the default value for conversions to the specified type.
`protected abstract Class<?>`	`getDefaultType()` Return the default type this `Converter` handles.
`protected <T> T`	`handleError(Class<T> type, Object value, Throwable cause)` Handle Conversion Errors.
`protected <T> T`	`handleMissing(Class<T> type)` Handle missing values.
`boolean`	`isUseDefault()` Indicates whether a default value will be returned or exception thrown in the event of a conversion error.
`protected void`	`setDefaultValue(Object defaultValue)` Set the default value, converting as required.
`String`	`toString()` Provide a String representation of this converter.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Constructor Detail
  - AbstractConverter
```
public AbstractConverter()
```
    Construct a Converter that throws a ConversionException if an error occurs.
  - AbstractConverter
```
public AbstractConverter(Object defaultValue)
```
    Construct a Converter that returns a default value if an error occurs.
    
    Parameters:
    
    defaultValue - The default value to be returned if the value to be converted is missing or an error occurs converting the value.
- Method Detail
  - conversionException
```
protected ConversionException conversionException(Class<?> type,
                                                  Object value)
```
    Generates a standard conversion exception with a message indicating that the passed in value cannot be converted to the desired target type.
    
    Parameters:
    
    type - the target type
    
    value - the value to be converted
    
    Returns:
    
    a ConversionException with a standard message
    
    Since:
    
    1.9
  - convert
```
public <T> T convert(Class<T> type,
                     Object value)
```
    Convert the input object into an output object of the specified type.
    
    Specified by:
    
    convert in interface Converter
    
    Type Parameters:
    
    T - the target type of the conversion
    
    Parameters:
    
    type - Data type to which this value should be converted
    
    value - The input value to be converted
    
    Returns:
    
    The converted value.
    
    Throws:
    
    ConversionException - if conversion cannot be performed successfully and no default is specified.
  - convertArray
```
protected Object convertArray(Object value)
```
    Return the first element from an Array (or Collection) or the value unchanged if not an Array (or Collection). This needs to be overriden for array/Collection converters.
    
    Parameters:
    
    value - The value to convert
    
    Returns:
    
    The first element in an Array (or Collection) or the value unchanged if not an Array (or Collection)
  - convertToString
```
protected String convertToString(Object value)
                          throws Throwable
```
    Convert the input object into a String.
    N.B.This implementation simply uses the value's toString() method and should be overriden if a more sophisticated mechanism for conversion to a String is required.
    
    Parameters:
    
    value - The input value to be converted.
    
    Returns:
    
    the converted String value.
    
    Throws:
    
    Throwable - if an error occurs converting to a String
  - convertToType
```
protected abstract <T> T convertToType(Class<T> type,
                                       Object value)
                                throws Throwable
```
    Convert the input object into an output object of the specified type.
    Typical implementations will provide a minimum of String to type conversion.
    
    Type Parameters:
    
    T - Target type of the conversion.
    
    Parameters:
    
    type - Data type to which this value should be converted.
    
    value - The input value to be converted.
    
    Returns:
    
    The converted value.
    
    Throws:
    
    Throwable - if an error occurs converting to the specified type
  - getDefault
```
protected Object getDefault(Class<?> type)
```
    Return the default value for conversions to the specified type.
    
    Parameters:
    
    type - Data type to which this value should be converted.
    
    Returns:
    
    The default value for the specified type.
  - getDefaultType
```
protected abstract Class<?> getDefaultType()
```
    Return the default type this Converter handles.
    
    Returns:
    
    The default type this Converter handles.
  - handleError
```
protected <T> T handleError(Class<T> type,
                            Object value,
                            Throwable cause)
```
    Handle Conversion Errors.
    If a default value has been specified then it is returned otherwise a ConversionException is thrown.
    
    Type Parameters:
    
    T - Target type of the conversion.
    
    Parameters:
    
    type - Data type to which this value should be converted.
    
    value - The input value to be converted
    
    cause - The exception thrown by the convert method
    
    Returns:
    
    The default value.
    
    Throws:
    
    ConversionException - if no default value has been specified for this Converter.
  - handleMissing
```
protected <T> T handleMissing(Class<T> type)
```
    Handle missing values.
    If a default value has been specified, then it is returned (after a cast to the desired target class); otherwise a ConversionException is thrown.
    
    Type Parameters:
    
    T - the desired target type
    
    Parameters:
    
    type - Data type to which this value should be converted.
    
    Returns:
    
    The default value.
    
    Throws:
    
    ConversionException - if no default value has been specified for this Converter.
  - isUseDefault
```
public boolean isUseDefault()
```
    Indicates whether a default value will be returned or exception thrown in the event of a conversion error.
    
    Returns:
    
    true if a default value will be returned for conversion errors or false if a ConversionException will be thrown.
  - setDefaultValue
```
protected void setDefaultValue(Object defaultValue)
```
    Set the default value, converting as required.
    If the default value is different from the type the Converter handles, it will be converted to the handled type.
    
    Parameters:
    
    defaultValue - The default value to be returned if the value to be converted is missing or an error occurs converting the value.
    
    Throws:
    
    ConversionException - if an error occurs converting the default value
  - toString
```
public String toString()
```
    Provide a String representation of this converter.
    
    Overrides:
    
    toString in class Object
    
    Returns:
    
    A String representation of this converter

Class AbstractConverter

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

AbstractConverter

AbstractConverter

Method Detail

conversionException

convert

convertArray

convertToString

convertToType

getDefault

getDefaultType

handleError

handleMissing

isUseDefault

setDefaultValue

toString