Socket in midp

Question

I wont to use socket connection in my midlet. I couldn't find the way to do this. I tryed to open ContentConnection or Stream connection but than i couldn't open inputstream nor datainputstream. On sun.com i found this code:
package com.sun.midp.io.j2me.socket;
import com.sun.cldc.io.ConnectionBase;
import javax.microedition.io.Connection;
import javax.microedition.io.StreamConnection;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import com.sun.cldc.io.j2me.socket.Protocol;
public class Protocol extends com.sun.cldc.io.j2me.socket.Protocol
public Connection c;
public Protocol()
super();
System.out.println("Protocol.ConnectionBase() called");
public void open(String uri, int mode, boolean to) throws IOExcepti
c = super.openPrim(uri, 0, false);
System.out.println("openPrim() called");
public InputStream openInputStream() throws IOException {
return super.openInputStream();
public DataInputStream openDataInputStream() throws IOException {
return super.openDataInputStream();
public OutputStream openOutputStream() throws IOException {
return super.openOutputStream();
public DataOutputStream openDataOutputStream() throws IOException {
return super.openDataOutputStream();
i used this but there always comes an exception:
Protocol.ConnectionBase() called
java.lang.IllegalArgumentException
     at com.sun.cldc.io.j2me.socket.Protocol.openPrim(+7)
     at com.sun.midp.io.InternalConnector.openPrim(+231)
     at com.sun.midp.io.InternalConnector.open(+9)
     at javax.microedition.io.Connector.open(+6)
     at javax.microedition.io.Connector.open(+6)
     at javax.microedition.io.Connector.open(+5)
     at KConnection.KConnector.open(+6)
     at KConnection.KConnector.connect(+6)
     at SerwisMain.getK(+18)
     at SerwisMain.startApp(+348)
     at javax.microedition.midlet.MIDletProxy.startApp(+7)
     at com.sun.midp.midlet.Scheduler.schedule(+225)
     at com.sun.midp.dev.DevMIDletSuiteImpl.schedule(+7)
     at com.sun.midp.Main.runLocalClass(+20)
     at com.sun.midp.Main.main(+68)
can anybodey tell me how can i open input and output stream and write and read from them as iwont and how long i wont?
Please help

Answer 1

First: what MIDP Version do you want to use? In MIDP 1.0 there are no sockets available, only HttpConnection and DatagramConnection. For socket use you have to deal with the MIDP 2.0
And in MIDP 2.0 you have a javax.microedition.io.SocketConnection which you can use for that.
// copied from the MIDP 2.0 Javadoc (javax.microedition.io.SocketConnection)
   SocketConnection sc = (SocketConnection)Connector.open("socket://host.com:79");
   sc.setSocketOption(SocketConnection.LINGER, 5);
   InputStream is  = sc.openInputStream();
   OutputStream os = sc.openOutputStream();
   os.write("\r\n".getBytes());
   int ch = 0;
   while(ch != -1) {
       ch = is.read();
   is.close();
   os.close();
   sc.close();you dont have to deal with com.sun.anything packages or classes unless you want to change the implemenation-details of the protocols.
hth
Kay