On Jan 10, 2008, at 5:15 AM, Nicolas Vienne wrote:
Hello everybody.
I have a little question about passing Structure between Java and
Native :
I noticed that the fields must be declared in the same order in
both side.
Since C determines the memory layout based on the order of
declaration, this is not exactly an onerous burden.
For example:
Java =
public class TestStruct extends Structure {
public int fieldA = 1;
public int fieldB = 2;
public int fieldC = 3;
}
C++ =
typedef struct TestStruct {
int fieldA;
int fieldB; // same ABC order in both sides
int fieldC;
} TestStruct;
Is there a way - other than avoiding structs - not to rely upon the
field order
? I mean that I cannot know the order of both sides and thus it
prevents me -
for now - from using JNA.
I think you're leaving out some critical details about what you're
trying to accomplish. Do you have some other high-level language
which is auto-generating the struct layout? You will *always* need
to tell the Java side how to map its struct fields into memory,
whether it's by convention or explicit configuration.
If you can't know the order of the C side, there's no way you can
access any given member of a C struct. On the Java side, you can
always use a Structure solely as internal data and bind the fields in
whatever manner you need to for the public API.
11 messages in net.java.dev.jna.usersRe: [jna-users] Structure Order
