Java : sample applet

 
 import java.applet.*;
 import java.awt.*;
 
 public class A extends Applet
 {
        private int w, h;
        public void init( )
        {
         w = 45;
         h = 50;
        }
    
        public void paint(Graphics g)
        {
         g.drawRect(w, h, 20, 80);
        }
 }

Sample J2Me Midlet for sound recording

import java.io.*;
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
import javax.microedition.media.*;
import javax.microedition.media.control.*;

public class VoiceRecordMidlet extends MIDlet {
      private Display display;

      public void startApp() {
            display = Display.getDisplay(this);
            display.setCurrent(new VoiceRecordForm());
      }

      public void pauseApp() {
      }

      public void destroyApp(boolean unconditional) {
            notifyDestroyed();
      }
}

class VoiceRecordForm extends Form implements CommandListener {
      private StringItem message;
      private StringItem errormessage;
      private final Command record, play;
      private Player player;
      private byte[] recordedAudioArray = null;
      public VoiceRecordForm() {
            super("Recording Audio");
            message = new StringItem("", "Select Record to start recording.");
            this.append(message);
            errormessage = new StringItem("", "");
            this.append(errormessage);
            record = new Command("Record", Command.OK, 0);
            this.addCommand(record);
            play = new Command("Play", Command.BACK, 0);
            this.addCommand(play);
            this.setCommandListener(this);
      }
      public void commandAction(Command comm, Displayable disp) {
            if (comm == record) {
                  Thread t = new Thread() {
                        public void run() {
                              try {
                                    player = Manager.createPlayer("capture://audio?encoding=pcm");
                                    player.realize();
                                    RecordControl rc = (RecordControl) player.getControl("RecordControl");
                                    ByteArrayOutputStream output = new ByteArrayOutputStream();
                                    rc.setRecordStream(output);
                                    rc.startRecord();
                                    player.start();
                                    message.setText("Recording...");
                                    Thread.sleep(5000);
                                    message.setText("Recording Done!");
                                    rc.commit();
                                    recordedAudioArray = output.toByteArray();
                                    player.close();
                              } catch (Exception e) {
                                    errormessage.setLabel("Error");
                                    errormessage.setText(e.toString());
                              }
                        }
                  };
                  t.start();

            }
            else if (comm == play) {
                  try {
                        ByteArrayInputStream recordedInputStream = new ByteArrayInputStream(recordedAudioArray);
                        Player p2 = Manager.createPlayer(recordedInputStream, "audio/basic");
                        p2.prefetch();
                        p2.start();
                  } catch (Exception e) {
                        errormessage.setLabel("Error");
                        errormessage.setText(e.toString());
                  }
            }
      }
} 

How to set up Jogre for the web

Set up jdk, apache tomcat, and hsqldb
==============================

apt-get install sun-java6-jdk
apt-get install tomcat5.5 tomcat5.5-wepapps tomcat5.5-admin
apt-get install hsqldb-server

Set up jogre
=========

wget http://voxel.dl.sourceforge.net/sourceforge/jogre/jogre_beta_0.3_bin.zip
cd /opt
unzip ~/jogre_beta_0.3.bin.zip
adduser jogre
chown -R jogre:jogre jogre
su jogre
cd
echo "export CLASSPATH=$CLASSPATH:/usr/share/java/hsqldb.jar:." >> .profile
source .profile
java org.hsqldb.Server &
cd /opt/jogre/server
chmod a+x *.sh


Configuration
==========

./server.sh &

#I prefer the gui; it's easier to just change the db settings with this tool
./administrator.sh &
#Login with admin, admin
#Change the database from xml to hsqldb
#The path to the db is jdbc:hsqldb:hsql://localhost/jogre_hsqldb

#restart the jogre server
killall server.sh
./server.sh &


#With apache tomcat admin (http://localhost:8180/admin), add jogreweb.war

Java - convert byte array to String

int len = (int)c.getLength();

            if (len > 0) {
                 int actual = 0;
                 int bytesread = 0 ;
                 byte[] data = new byte[len];
                 while ((bytesread != len) && (actual != -1)) {
                     actual = is.read(data, bytesread, len - bytesread);
                     bytesread += actual;
                    
                 }

//assuming utf-8 encoding
                 String test = new String(data,0,data.length,"UTF8");
                 System.out.println(test);

Java - how to make an anonymous thread

Creating an anonymous thread is pretty easy. If you want to make a thread that performs a simple operation anonymous threads can be convenient.

Java threads perform their task in the run() function, which is initiated with the start method.

Here is an example:

  Thread t = new Thread( new Runnable(){
              public void run(){
                     System.out.println("    do some work");
                         
                     
              }
          });
  
  t.start();

Hello world Midlet

import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.Form;
import javax.microedition.midlet.MIDlet;
import javax.microedition.midlet.MIDletStateChangeException;


public class LoginScreen extends MIDlet {

public LoginScreen() {
// TODO Auto-generated constructor stub
}

protected void destroyApp(boolean arg0) throws MIDletStateChangeException {
// TODO Auto-generated method stub

}

protected void pauseApp() {
// TODO Auto-generated method stub

}

protected void startApp() throws MIDletStateChangeException {
// TODO Auto-generated method stub

Form f = new Form("Login Form");
Display d = Display.getDisplay(this);
d.setCurrent(f);

f.append("Hello");

}

}

Java Me Notes

Links

Main site

http://java.sun.com/javame/index.jsp

Download

http://java.sun.com/products/sjwtoolkit/download.html

Eclipse plugin

http://download.eclipse.org/dsdp/mtj/updates/0.9/stable/

Need to use eclipse to export jad and jar for the project (which is in deploy)


Conventions

startApp() --> like main

import javax.microedition.lcdui.*; //required to use display

Display // interface with phone screen

Form //set up the screen then attach it to display

myform.append("some text"); //a label

Create Messagebox / popup for Java

//Assuming that the current object is a JFrame:

JOptionPane.showMessageDialog(this, "Some Message");