COM/Java Type Mappings

jSegue maps types used in COM and OLE Automation to Java types. In many cases the mapping should be natural to Java developers. For example, OLE Automation servers commonly use the BSTR type to represent a string containing wide characters. jSegue maps the BSTR type to java.lang.String.

When jSegue creates the Java object for a VARIANT it will create an instance of a class that will represent the VARIANT's value. For example if the VARIANT contains a value of type VT_I2, jSegue will create a java.lang.Short instance to return the VARIANT's value. To figure out the specific object type use this mapping against the VARTYPE of the VARIANT. For primitive types use the corresponding Java object type. To pass in VT_EMPTY or VT_NULL use com.moesol.bindings.platform_sdk.component_services.VARIANT.EMPTY or com.moesol.bindings.platform_sdk.component_services.VARIANT.NULL.

Below is the current jSegue mapping of COM/OLE types to Java types. One of the goals of these mappings was preserving the value range of the native type. For example, a BYTE (unsigned char) has a value range of 0 to 255. In java byte has a value range of -128 to 127, so the next larger integer form was choosen. Another possible mapping is mapping based on the size of the type. So a native BYTE would map to a java byte. Arrays would convert faster, but at the convenience of having to map 255 to -127. Post to the forums if you are interested in this change.

COM Type Java Type Notes
UI1 short short allows 255
UI2 char
UI4 long
UI8 java.math.BigInteger
UINT long
INT int
I1 byte
I2 short
I4 int
I8 long
R4 float
R8 double
CY long Scaled by 10,000 (see VARIANTARG documentation)
BSTR java.lang.String
LPSTR java.lang.String
LPWSTR java.lang.String
DECIMAL not mapped
DATE java.util.Date DATE truncates java.util.Date to whole seconds
DISPATCH com.moesol.bindings.platform_sdk
VARIANT varies (see comments above)
UNKNOWN com.moesol.bindings.platform_sdk
SAFEARRAY(com_type) jsegue_type[] For example, SAFEARRAY(INT) maps to int[]

$Id: com_java_mappings.html 3769 2007-06-08 19:06:43Z hastings $