java - JNA wrong structure field values -

i'm dancing around jna adapter "twain.h" - did it, still have problems getting scanner capabilities. there original enity:

typedef unsigned short tw_uint16, far *ptw_uint16; typedef unsigned long  tw_uint32, far *ptw_uint32;  typedef struct {    tw_uint16  itemtype;    tw_uint32  minvalue;     /* starting value in range.           */    tw_uint32  maxvalue;     /* final value in range.              */    tw_uint32  stepsize;     /* increment minvalue maxvalue.   */    tw_uint32  defaultvalue; /* power-up value.                        */    tw_uint32  currentvalue; /* value in effect. */ } tw_range, far * ptw_range; 

this mapping (thnx jnaerator)

public static class tw_range extends structure {         /** c type : tw_uint16 */         public short itemtype;         /** c type : tw_uint32 */         public nativelong minvalue;         /** c type : tw_uint32 */         public nativelong maxvalue;         /** c type : tw_uint32 */         public nativelong stepsize;         /** c type : tw_uint32 */         public nativelong defaultvalue;         /** c type : tw_uint32 */         public nativelong currentvalue;         public tw_range() {             super();         }         protected list<? > getfieldorder() {             return arrays.aslist("itemtype", "minvalue", "maxvalue", "stepsize", "defaultvalue", "currentvalue");         } } 

when i'm asking scanner entity, scanner sends me filled object, when create through

new tw_range(pointer) 

it returns me wired stuff

twaindsmlibrary$tw_range(native@0x157c000c) (22 bytes) {   short itemtype@0=870   nativelong minvalue@2=1572916   nativelong maxvalue@6=5500   nativelong stepsize@a=2097152   nativelong defaultvalue@e=5500   nativelong currentvalue@12=2621440 } 

1. how can interpret values?
2. can dump native structure , analyze tool? have seen pointer.dump, requires size of dumped value, how can size of structure under pointer?

structure.read() must called in order copy native memory jna structure fields.

the easiest way ensure structure.read() called tw_range(pointer) constructor last statement.

jna calls structure.read()/write() automatically when making function calls. intentionally not in structure constructors, leaving programmer decide best point @ perform synchronization (if @ all).