关于MIDlet.platformRequest(String URL) 调用具体程序代码

package phonemode;

import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
import javax.microedition.io.*;

public class OBJ extends MIDlet implements CommandListener{
static OBJ instance;
TextField field;
Command cmdCall;
String phonenum;

Menu menu = new Menu();
public OBJ() {
instance = this;
field = new TextField("号码：", "", 20, TextField.PHONENUMBER);
cmdCall = new Command("拨打", Command.OK, 0);
menu.append(field);
menu.addCommand(cmdCall);
menu.setCommandListener(instance);
}
void CallPhone(String num){
try {
platformRequest("tel:" + num);
}
catch (ConnectionNotFoundException ex) {
System.out.println("CallPhone "+ex);
}
}

public void commandAction(Command command, Displayable displ