How to pass a large structure through JNI from C to JAVA

Question

Is it possible to pass a large Structure through JNI from C to Java?

Can somebody please give me the possible solutions?

Normally, you need to create a Java structure which is a copy of the C structure and pass that back. You cannot use C data types in Java (or visa-versa directly) — Peter Lawrey
– Peter Lawrey, Commented Feb 8, 2011 at 20:45
@Peter Lawrey may be you can help me with this question stackoverflow.com/questions/6215374/from-c-code-to-java-and-jni ? — Viktor Apoyan
– Viktor Apoyan, Commented Jun 3, 2011 at 10:12

rmk · Accepted Answer · 2011-02-08 20:47:47Z

3

Declare a pointer to the struct in your java class like so:

protected long ptrToX;

Next, to set it:

Get the field ID using (*env)->GetFieldID(...)
Get the pointer using (*env)->GetLongField(...)
Set the pointer using (*env)->SetLongField(...)

To get it, just follow the first two steps mentioned above.

Always remember to include a finaliser that will take care of deallocating the pointer when the object is garbage-collected. Alternatively, if you do not want to incur the performance hit incurred by using finalisers, just provide a terminate() method that deallocates the pointer.

answered Feb 8, 2011 at 20:47

rmk

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Comments

Ujjwal · Accepted Answer · 2011-02-09 08:19:21Z

1

Better you switch to JNA, It's much convenient way to program from C to JAVA.

answered Feb 9, 2011 at 8:19

Ujjwal

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