18.4.2.Virtuoso/PL <-> Java VM Type Mapping Schema
Since the Java language uses a different set of data types than Virtuoso a type mapping system has been established to allow the passage of data to and from Java. All Java simple types are mapped to a corresponding Virtuoso type as follows:
Table18.1.Java - Virtuoso Data Type Mapping
| Java Type/Class | Virtuoso Internal Type |
|---|---|
| boolean | smallint |
| char | smallint |
| double | double precision |
| float | real |
| int | integer |
| short | integer |
| long | integer |
| boolean | smallint |
| java.lang.String | NVARCHAR |
| java.util.Date | DATETIME |
All other Java objects are represented as a special Virtuoso
value, which contains a reference to the Java object in the VM
memory space. When such a value is returned as a Virtuoso/PL return
value or as a result set column, it calls the java.lang.Object.toString() method for the Java
VM object it refers to and that result is returned to the calling
client.
Arrays are mapped to a Virtuoso vector of their elements. The array handling routines are recursive, so each element may be a Java array or a scalar type.
The above mappings are applied when converting Virtuoso/PL data to Java data as follows:
| method parameter values in java_call_method VSE |
| method parameter values in java_new_object VSE |
| property values in java_set_property VSE |
| the instance parameters in java_call_method/java_get_property/java_set_property VSEs |
The above mappings are applied in the opposite direction (Java Data -> Virtuoso/PL data) as follows:
| method return values in java_call_method VSE |
| return value of the java_new_object VSE |
| property values returned from java_get_property VSE |