| Generic
Converter implementaion that handles conversion
to and from array objects.
Can be configured to either return a default value or throw a
ConversionException if a conversion error occurs.
The main features of this implementation are:
- Element Conversion - delegates to a
Converter ,
appropriate for the type, to convert individual elements
of the array. This leverages the power of existing converters
without having to replicate their functionality for converting
to the element type and removes the need to create a specifc
array type converters.
- Arrays or Collections - can convert from either arrays or
Collections to an array, limited only by the capability
of the delegate
Converter .
- Delimited Lists - can Convert to and from a
delimited list in String format.
- Conversion to String - converts an array to a
String in one of two ways: as a delimited list
or by converting the first element in the array to a String - this
is controlled by the
ArrayConverter.setOnlyFirstToString(boolean) parameter.
- Multi Dimensional Arrays - its possible to convert a
String
to a multi-dimensional arrays, by embedding
ArrayConverter within each other - see example below.
- Default Value
- No Default - use the
ArrayConverter.ArrayConverter(ClassConverter) constructor to create a converter which throws a
ConversionException if the value is missing or
invalid.
- Default values - use the
ArrayConverter.ArrayConverter(ClassConverterint) constructor to create a converter which returns a default
value. The defaultSize parameter controls the
default value in the following way:
- defaultSize < 0 - default is
null
- defaultSize = 0 - default is an array of length zero
- defaultSize > 0 - default is an array with a
length specified by
defaultSize (N.B. elements
in the array will be null)
Parsing Delimited Lists
This implementation can convert a delimited list in String format
into an array of the appropriate type. By default, it uses a comma as the delimiter
but the following methods can be used to configure parsing:
setDelimiter(char) - allows the character used as
the delimiter to be configured [default is a comma].setAllowedChars(char[]) - adds additional characters
(to the default alphabetic/numeric) to those considered to be
valid token characters.
Multi Dimensional Arrays
It is possible to convert a String to mulit-dimensional arrays by using
ArrayConverter as the element
Converter within another
ArrayConverter .
For example, the following code demonstrates how to construct a
Converter to convert a delimited String into a two dimensional integer array:
// Construct an Integer Converter
IntegerConverter integerConverter = new IntegerConverter();
// Construct an array Converter for an integer array (i.e. int[]) using
// an IntegerConverter as the element converter.
// N.B. Uses the default comma (i.e. ",") as the delimiter between individual numbers
ArrayConverter arrayConverter = new ArrayConverter(int[].class, integerConverter);
// Construct a "Matrix" Converter which converts arrays of integer arrays using
// the pre-ceeding ArrayConverter as the element Converter.
// N.B. Uses a semi-colon (i.e. ";") as the delimiter to separate the different sets of numbers.
// Also the delimiter used by the first ArrayConverter needs to be added to the
// "allowed characters" for this one.
ArrayConverter matrixConverter = new ArrayConverter(int[][].class, arrayConverter);
matrixConverter.setDelimiter(';');
matrixConverter.setAllowedChars(new char[] {','});
// Do the Conversion
String matrixString = "11,12,13 ; 21,22,23 ; 31,32,33 ; 41,42,43";
int[][] result = (int[][])matrixConverter.convert(int[][].class, matrixString);
version:
$Revision: 555824 $ $Date: 2007-07-13 01:27:15 +0100 (Fri, 13 Jul 2007) $
since:
1.8.0 |
