如何实现自定义类的引用

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;
import java.net.UnknownHostException;

public class UDPClient implements Runnable{
final static int udpPort = 9999;
final static String hostIp = "192.168.1.4";

public UDPClient(){  
    super();  
}  

}

• 以上UDPClienta是自定义类。
• 在MainActivity中被引用。

• public class MainActivity extends AppCompatActivity {

  TextView txt_Recv,txt_Send;
  Button btn_CleanRecv,btn_Send,btn_UdpConn,btn_UdpClose;
  EditText edit_Send;
  private UDPClient client = null;
  public static Context context;
  private final MyHandler myHandler = new MyHandler(this);
  private StringBuffer udpRcvStrBuf=new StringBuffer(),udpSendStrBuf=new StringBuffer();

请问，改为native.js 应如何写呢。