int my_function(char* param1, struct answer* ans);

#pragma pack(1)
struct answer{
  int TType;                   //IN
  unsigned long Amount;   //IN
  char          Rcode   [2+1];  //OUT
  char          AMessage[16 ]; //OUT
  int           CType;              //OUT
  char*         Check;            //OUT
};

  public interface My_Dll extends Library {
        public static class answer extends Structure {
                    public static class ByReference extends answer implements Structure.ByReference {}
                    
              public int  TType      = 0;                   
              public int  Amount     = 0;        
              public byte Rcode[]    = new byte[3]; //выход: 
              public byte AMessage[] = new byte[16]; //выход: 
              public int  CType      = 0;         //выход: 
              public Pointer Check;         //выход: 
              protected List getFieldOrder() {
                      return Arrays.asList(new String[] {"TType", "Amount", "Rcode","AMessage", "CType","Check"});
              }
        }
        public int my_function(byte track2[], answer.ByReference ans);
  }

  public static void Start() {
      My_Dll test_dll = (My_Dll) Native.loadLibrary("my_dll", My_Dll.class);
      My_Dll.answer.ByReference aa = new My_Dll.answer.ByReference();
      // определяем In
      aa.Amount = 100;
      aa.TType =3;

      int result = test_dll.my_function(null,aa);
      // выводим OUT
      System.out.println("Result: "  + result);
      System.out.println("Rcode: "  + new String(aa.Rcode));
      System.out.println("Amessage: " + new String(aa.AMessage));
}

PointerByReference Check = new PointerByReference(); 
...
Pointer p =  Check.getValue();

Unexpected Signal : EXCEPTION_ACCESS_VIOLATION (0xc0000005) occurred at PC=0x2E863B1
Function=Java_com_sun_jna_Native__1getPointer+0x21
Library=C:\Documents and Settings\pra_2\Local Settings\Temp\jna-pra_2\jna30865.dll

Current Java thread:
	at com.sun.jna.Native._getPointer(Native Method)
	at com.sun.jna.Native.getPointer(Native.java:1776)
	at com.sun.jna.Pointer.getPointer(Pointer.java:664)
	at com.sun.jna.ptr.PointerByReference.getValue(PointerByReference.java:37)
	at test.JNATestClass.StartPinpad(JNATestClass.java:118)
	at test.JNATestClass.main(JNATestClass.java:167)

Dynamic libraries:
0x00400000 - 0x0040B000 	C:\soft\JDeveloper\jdk1.4\bin\javaw.exe

 public interface My_Dll extends Library {
        public static class answer extends Structure {
                    public static class ByReference extends answer implements Structure.ByReference {}
                    
              public int  TType      = 0;                   
              public int  Amount     = 0;        
              public byte Rcode[]    = new byte[3]; //выход: 
              public byte AMessage[] = new byte[16]; //выход: 
              public int  CType      = 0;         //выход: 
              public PointerByReference Check;         //выход: 
              protected List getFieldOrder() {
                      return Arrays.asList(new String[] {"TType", "Amount", "Rcode","AMessage", "CType","Check"});
              }
        }
        public int my_function(byte track2[], answer.ByReference ans);
  }

  public static void Start() {
      My_Dll test_dll = (My_Dll) Native.loadLibrary("my_dll", My_Dll.class);
      My_Dll.answer.ByReference aa = new My_Dll.answer.ByReference();
      // определяем In
      aa.Amount = 100;
      aa.TType =3;

      int result = test_dll.my_function(null,aa);
      // выводим OUT
      System.out.println("Result: "  + result);
      System.out.println("Rcode: "  + new String(aa.Rcode));
      System.out.println("Amessage: " + new String(aa.AMessage));
      
      Pointer p =  aa.Check.getValue();// на этой строчке возникает ошибка
}

  int result = test_dll.my_function(null,aa);