The class and shape of each column in a StarTable
(accessed using the get/setContentClass() and
get/setShape() methods of
ColumnInfo)
correspond to the
datatype and arraysize attributes of the
corresponding FIELD element in the VOTable.
You are not expected to access the
datatype and arraysize attributes directly.
How Java classes map to VOTable data types for the content of
columns is similar to elsewhere in STIL.
In general, scalars are represented by the corresponding primitive
wrapper class (Integer, Double, Boolean
etc), and arrays are represented by an array of primitives
of the corresponding type (int[], double[],
boolean[]).
Arrays are only ever one-dimensional - information about any
multidimensional shape they may have is supplied separately
(use the getShape method on the corresponding
ColumnInfo).
There are a couple of exceptions to this: arrays with
datatype="char" or "unicodeChar"
are represented by String objects
since that is almost always what is intended
(n-dimensional arrays of char are treated as if they were
(n-1)-dimensional arrays of Strings),
and unsignedByte types are represented as if they were
shorts, since in Java bytes are always signed.
Complex values are represented as if they were an array of the corresponding
type but with an extra dimension of size two (the most rapidly varying).
The following table summarises how all VOTable datatypes are represented:
datatype Class for scalar Class for arraysize>1
-------- ---------------- ---------------------
boolean Boolean boolean[]
bit boolean[] boolean[]
unsignedByte Short short[]
short Short short[]
int Integer int[]
long Long long[]
char Char String or String[]
unicodeChar Char String or String[]
float Float float[]
double Double double[]
floatComplex float[] float[]
doubleComplex double[] double[]