public class TTM {

public interface WrapperDLL extends Library {
    WrapperDLL INSTANCE = (WrapperDLL) Native.loadLibrary("TransportRE", WrapperDLL.class);

    int TRE_send(int channel, Pointer data, int len);

}
public int Send (int channel, String data, int len) {
    WrapperDLL wdll = WrapperDLL.INSTANCE;

    Memory mem = new Memory(data.length()+1);
    mem.setString(0, data);
    int byteSent = wdll.TRE_send(channel_id, mem.getPointer(0), len);
    // at this (TRE_send) point the VM crashes !!!!

  return byteSent;
}

public int Send (int channel, String data, int len) {
    WrapperDLL wdll = WrapperDLL.INSTANCE;

    Memory mem = new Memory(data.length()+1);
    mem.setString(0, data);
    int byteSent = wdll.TRE_send(channel_id, mem, len);

  return byteSent;
}

void send(String);
  void send(Pointer);
  void send(MyStructure);

int byteSent = wdll.TRE_send(channel_id, data.toCharArray(), len);