Gamasutra - Features - "Creating Games using J2ME" [09.17.01]

Code Listing: Number Picker

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

public class NumberPick extends MIDlet implements CommandListener
{
    // This hostname may be a server or the IP of another phone
    static final String hostname = "myserver.com";
    static final int sendport         = 9000;
    static final int receiveport      = 9001;

    static boolean gotResult = false;

    private Display myDisplay;

    Receive receiveThread = new Receive();

    private Alert responseAlert;

    private Form searchwait;
    private Form pickscreen;

    TextField pickedNumber;
    private Command PICK = new Command("Pick One", Command.OK, 1);
    private Command OK = new Command("Try Again", Command.OK, 1);

    public NumberPick()
    {
    }

    public void startApp()
    {
       // Set up the Pick A Number screen
       pickscreen = new Form("Pick A Number");
       pickedNumber = new TextField("Between 0 and 9:","",1, TextField.NUMERIC);
       pickscreen.append(pickedNumber);
       pickscreen.addCommand(PICK);
       pickscreen.setCommandListener(this);

       // Set up a Searching, Please Wait screen
       searchwait = new Form("Searching...");
       searchwait.append(new StringItem("Wait","Please wait..."));
       searchwait.addCommand(OK);
       searchwait.setCommandListener(this);

       // Set up a Response Alert screen
       responseAlert = new Alert("And Your Guess Is...");
       responseAlert.setTimeout(Alert.FOREVER);

       myDisplay = Display.getDisplay(this);
       myDisplay.setCurrent(pickscreen);

        // Start the Listening thread
        receiveThread.start();
    }

    public void pauseApp()
    {
    }

    public void destroyApp(boolean unconditional)
    {
    }


    public void commandAction(Command c, Displayable d)
    {
        if (d == pickscreen && c == PICK)
        {
            String request = pickedNumber.getString();
           if ( !request.equals("") )
            {
              myDisplay.setCurrent(searchwait);
              sendPick(request);
           }
        }
    }

    void sendPick(String thepick)
    {
        // Now send the pick...
        byte[] message = new byte[1];
        System.arraycopy(thepick.getBytes(), 0, message, 0,1);

        DatagramConnection dc = null;

        String destAddr = "datagram://" + hostname + ":" + sendport;

        try {
            dc = (DatagramConnection)Connector.open(destAddr);

           // Create a datagram socket and send
            Datagram dgram= dc.newDatagram(message,1,destAddr);
            dc.send(dgram);
            dc.close();
        }
        catch (Exception e)
        {
            System.out.println("Connecting Exception: " + e.getMessage());
            if (dc != null) {
                try {
                    dc.close();
                }
                catch (Exception f)
                {
                   System.out.println("Exception Closing: " + f.getMessage());
                }
            }
        }
    }

    class Receive extends Thread
    {
        public void run()
        {
            doReceive();
        }

        void doReceive()
        {
            DatagramConnection dc = null;
          Datagram dgram;

            try
            {
                dc = (DatagramConnection)Connector.open("datagram://:"+receiveport);

                String reply;

                while (true)
                {
                    dgram = dc.newDatagram(dc.getMaximumLength());
                    dc.receive(dgram);
                    reply = new String(dgram.getData(), 0,dgram.getLength());
                    if (reply.equals("Y"))
                    {
                     responseAlert.setString("100% right!");
                       myDisplay.setCurrent(responseAlert,pickscreen);
                    }
                    else
                    {
                       myDisplay.setCurrent(responseAlert,pickscreen);
                       responseAlert.setString("Wrong as can be!");
                    }
                    try
                    {
                       Thread.sleep(500);
                    }
                    catch (Exception e)
                    { }
                }

            }
            catch (Exception e)
            {
                System.out.println("Exception: " + e.getMessage());

                if (dc != null)
                {
                    try
                    {
                       dc.close();

                    }
                    catch (Exception f)
                    {
                        System.out.println("Exception: " + f.getMessage());
                    }
                }
            }
        }
     }
}


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