How to Install Apache Ant

Its really simple.
1. Make sure you have java environment installed in your system.
2. Download Ant binary distribution form here.
3. Uncompress the file downloaded.
4. Set the environment variables.

         Click new button to add new environment variable. Type "ANT_HOME" as the variable name and give the path of the directory where you uncompress Ant as the value. Then edit the path variable. For Windows add %ANT_HOME%/bin and for Linux add ${ANT_HOME}/bin to the value value of the path variable. At the end the value of the path variable should be shown like this. C:\Program Files\Java\jdk1.6.0_22\bin ; %ANT_HOME%/bin.

5. Click OK and save all the changes.

Now your are ready to use Apache Ant.

You can make sure that Ant is installed correctly by executing the command 

ant -version in command prompt. If it is installed correctly it should show the version information of Ant distribution. 

Apache Ant - Java-Based Build Tool

                 

                  Apache Ant is a powerful Java-based build tool which automates the building process of a project. Mainly Ant is used to build Java applications. But It supports many program application like C, C++, Python etc. Ant can be used to many purposes. If we want to get the results of several programs which is written and executed in different languages we can use ant to do that.
                 We can configure Ant project by using "build.xml". "build.xml" is normal xml file. There we can define all the tasks, properties and variable which are used in the build process. Ant has lost of free defined tasks. Also We can define our own task.
                  After preparing the build.xml file we can simply execute "ant" command in command prompt of terminal. Then it builds the project.
                  Ant support both Windows and Linux platforms. You cant download the binary distribution of Ant form here. For more information you can refer the Apache Ant Project Site.
I hope to bring you series of post about Apache Ant.

Brightness Changing Algorithm - Image Processing Basic

There are many libraries which are used to Image processing applications. But the algorithms behind these libraries use basic mathematical operation. I hope to bring you series of blog posts which describe the fundamental image processing algorithms implemented in mathematical operation without using any library. Following java class change the brightness of an image.
We should input our image to the method changeBrightness as a BufferedImage. increasingFactor is an integer which determine the brightness level of the image. Positive values will increase the brightness while negative values decrees. Range of the increasingFactor should be between -255 to 255.

Original Image

Brightness Increased

Brightness Decreased

	package lakj.comspace.imageprocessor;
	import java.awt.Color;
	import java.awt.image.BufferedImage;
	/**
	*Brightness Changing Class
	*by
	*Lak J Comspace
	*
	*/
	public class Brightness {
	public BufferedImage changeBrightness(BufferedImage inImage, int increasingFactor) {
	//size of input image
	int w = inImage.getWidth();
	int h = inImage.getHeight();
	BufferedImage outImage = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
	//Pixel by pixel navigation loop
	for (int i = 0; i < w; i++) {
	for (int j = 0; j < h; j++) {
	//get the RGB component of input imge pixel
	Color color = new Color(inImage.getRGB(i, j));
	int r, g, b;
	//change the value of each component
	r = color.getRed() + increasingFactor;
	g = color.getGreen() + increasingFactor;
	b = color.getBlue() + increasingFactor;
	//r,g,b values which are out of the range 0 to 255 should set to 0 or 255
	if (r >= 256) {
	r = 255;
	} else if (r < 0) {
	r = 0;
	}
	if (g >= 256) {
	g = 255;
	} else if (g < 0) {
	g = 0;
	}
	if (b >= 256) {
	b = 255;
	} else if (b < 0) {
	b = 0;
	}
	//set output image pixel component
	outImage.setRGB(i, j, new Color(r, g, b).getRGB());
	}
	}
	return outImage;
	}
	}

view raw Brightness.java hosted with ❤ by GitHub

Android Application to Send a File to Remote Server

This simple Android application sends a file to a remote server. In this example code server runs on local host. When the Send button is clicked the file is sent to the server.

Android Client Application

	<manifest android:versioncode="1" android:versionname="1.0" package="lakj.comspace.simpleclient"
	xmlns:android="http://schemas.android.com/apk/res/android">
	<uses-sdk android:minsdkversion="10">
	<uses-permission android:name="android.permission.INTERNET"></uses-permission>
	<application android:icon="@drawable/ic_launcher" android:label="@string/app_name">
	<activity android:label="@string/app_name" android:name=".SimpleClientActivity">
	<intent-filter>
	<action android:name="android.intent.action.MAIN">
	<category android:name="android.intent.category.LAUNCHER">
	</category>
	</action>
	</intent-filter>
	</activity>
	</application>
	</uses-sdk>
	</manifest>

view raw AndroidManifest.xml hosted with ❤ by GitHub

	<linearlayout android:layout_height="fill_parent" android:layout_width="fill_parent" android:orientation="vertical"
	xmlns:android="http://schemas.android.com/apk/res/android">
	<textview android:id="@+id/textView1" android:layout_height="wrap_content" android:layout_width="wrap_content"
	android:textappearance="?android:attr/textAppearanceLarge">
	<button android:id="@+id/button1" android:layout_gravity="center" android:layout_height="wrap_content"
	android:layout_width="wrap_content" android:text="Send">
	</button>
	</textview>
	</linearlayout>

view raw main.xml hosted with ❤ by GitHub

	/*
	* This is a simple Android mobile client
	* This application send any file to a remort server when the
	* send button is pressed
	* Author by Lak J Comspace
	*/
	package lakj.comspace.simpleclient;
	import java.io.BufferedInputStream;
	import java.io.File;
	import java.io.FileInputStream;
	import java.io.IOException;
	import java.io.OutputStream;
	import java.net.Socket;
	import java.net.UnknownHostException;
	import android.app.Activity;
	import android.os.Bundle;
	import android.view.View;
	import android.widget.Button;
	import android.widget.TextView;
	public class SimpleClientActivity extends Activity {
	private Socket client;
	private FileInputStream fileInputStream;
	private BufferedInputStream bufferedInputStream;
	private OutputStream outputStream;
	private Button button;
	private TextView text;
	@Override
	public void onCreate(Bundle savedInstanceState) {
	super.onCreate(savedInstanceState);
	setContentView(R.layout.main);
	button = (Button) findViewById(R.id.button1); //reference to the send button
	text = (TextView) findViewById(R.id.textView1); //reference to the text view
	//Button press event listener
	button.setOnClickListener(new View.OnClickListener() {
	public void onClick(View v) {
	File file = new File("/mnt/sdcard/input.jpg"); //create file instance
	try {
	client = new Socket("10.0.2.2", 4444);
	byte[] mybytearray = new byte[(int) file.length()]; //create a byte array to file
	fileInputStream = new FileInputStream(file);
	bufferedInputStream = new BufferedInputStream(fileInputStream);
	bufferedInputStream.read(mybytearray, 0, mybytearray.length); //read the file
	outputStream = client.getOutputStream();
	outputStream.write(mybytearray, 0, mybytearray.length); //write file to the output stream byte by byte
	outputStream.flush();
	bufferedInputStream.close();
	outputStream.close();
	client.close();
	text.setText("File Sent");
	} catch (UnknownHostException e) {
	e.printStackTrace();
	} catch (IOException e) {
	e.printStackTrace();
	}
	}
	});
	}
	}

view raw SimpleClientActivity.java hosted with ❤ by GitHub

Server Application

	/*
	* This is a simple server application
	* This server receive a file from a Android client and save it in a given place.
	* Author by Lak J Comspace
	*/
	package simpleserver;
	import java.io.BufferedOutputStream;
	import java.io.FileOutputStream;
	import java.io.IOException;
	import java.io.InputStream;
	import java.net.ServerSocket;
	import java.net.Socket;
	public class Main {
	private static ServerSocket serverSocket;
	private static Socket clientSocket;
	private static InputStream inputStream;
	private static FileOutputStream fileOutputStream;
	private static BufferedOutputStream bufferedOutputStream;
	private static int filesize = 10000000; // filesize temporary hardcoded
	private static int bytesRead;
	private static int current = 0;
	public static void main(String[] args) throws IOException {
	serverSocket = new ServerSocket(4444); //Server socket
	System.out.println("Server started. Listening to the port 4444");
	clientSocket = serverSocket.accept();
	byte[] mybytearray = new byte[filesize]; //create byte array to buffer the file
	inputStream = clientSocket.getInputStream();
	fileOutputStream = new FileOutputStream("D:\\output.jpg");
	bufferedOutputStream = new BufferedOutputStream(fileOutputStream);
	System.out.println("Receiving...");
	//following lines read the input slide file byte by byte
	bytesRead = inputStream.read(mybytearray, 0, mybytearray.length);
	current = bytesRead;
	do {
	bytesRead = inputStream.read(mybytearray, current, (mybytearray.length - current));
	if (bytesRead >= 0) {
	current += bytesRead;
	}
	} while (bytesRead > -1);
	bufferedOutputStream.write(mybytearray, 0, current);
	bufferedOutputStream.flush();
	bufferedOutputStream.close();
	inputStream.close();
	clientSocket.close();
	serverSocket.close();
	System.out.println("Sever recieved the file");
	}
	}

view raw main.java hosted with ❤ by GitHub

Simple Client-Server Application for Android

Note: Here is the updated tutorial of the following tutorial for the latest Android version:
http://lakjeewa.blogspot.com/2014/05/simple-android-client-server-application.html 
Following tutorial is based on Android 2.3 (API Level 10). It is not compatible with later versions since API Level 11 introduced AsyncTask implementation for network communication. Refer the above link instead for working solution. 

This application is a simple client-server application which has a Android mobile client and a Java server which is run on a machine. In this example, client is run on the Android emulator and the server is run on the local host. In Android 10.0.2.2 is the IP address for local host. This application allow to type a text message on a text field and when the Send button is press the message is sent to the server. Server continuously listen to the port. When there is a incoming message server read it and show it on the standard output.

Client Side Application

	<manifest android:versioncode="1" android:versionname="1.0" package="lakj.comspace.simpleclient"
	xmlns:android="http://schemas.android.com/apk/res/android">
	<uses-sdk android:minsdkversion="10">
	<uses-permission android:name="android.permission.INTERNET"></uses-permission>
	<application android:icon="@drawable/ic_launcher" android:label="@string/app_name">
	<activity android:label="@string/app_name" android:name=".SimpleClientActivity">
	<intent-filter>
	<action android:name="android.intent.action.MAIN">
	<category android:name="android.intent.category.LAUNCHER">
	</category>
	</action>
	</intent-filter>
	</activity>
	</application>
	</uses-sdk>
	</manifest>

view raw AndroidManifest.xml hosted with ❤ by GitHub

	<linearlayout android:layout_height="fill_parent" android:layout_width="fill_parent" android:orientation="vertical"
	xmlns:android="http://schemas.android.com/apk/res/android">
	<edittext android:id="@+id/editText1" android:inputtype="textMultiLine" android:layout_height="wrap_content"
	android:layout_width="match_parent">
	<requestfocus>
	</requestfocus>
	</edittext>
	<button android:id="@+id/button1" android:layout_gravity="center" android:layout_height="wrap_content"
	android:layout_width="wrap_content" android:text="Send">
	</button>
	</linearlayout>

view raw main.xml hosted with ❤ by GitHub

	/*
	* This is a simple Android mobile client
	* This application read any string messege typed on the text field and
	* send it to the server when the Send button is pressed
	* Author by Lak J Comspace
	*/
	package lakj.comspace.simpleclient;
	import java.io.IOException;
	import java.io.PrintWriter;
	import java.net.Socket;
	import java.net.UnknownHostException;
	import android.app.Activity;
	import android.os.Bundle;
	import android.view.View;
	import android.widget.Button;
	import android.widget.EditText;
	public class SimpleClientActivity extends Activity {
	private Socket client;
	private PrintWriter printwriter;
	private EditText textField;
	private Button button;
	private String messsage;
	@Override
	public void onCreate(Bundle savedInstanceState) {
	super.onCreate(savedInstanceState);
	setContentView(R.layout.main);
	textField = (EditText) findViewById(R.id.editText1); //reference to the text field
	button = (Button) findViewById(R.id.button1); //reference to the send button
	//Button press event listener
	button.setOnClickListener(new View.OnClickListener() {
	public void onClick(View v) {
	messsage = textField.getText().toString(); //get the text message on the text field
	textField.setText(""); //Reset the text field to blank
	try {
	client = new Socket("10.0.2.2", 4444); //connect to server
	printwriter = new PrintWriter(client.getOutputStream(), true);
	printwriter.write(messsage); //write the message to output stream
	printwriter.flush();
	printwriter.close();
	client.close(); //closing the connection
	} catch (UnknownHostException e) {
	e.printStackTrace();
	} catch (IOException e) {
	e.printStackTrace();
	}
	}
	});
	}
	}

view raw SlimpleClientActivity.java hosted with ❤ by GitHub

Server Side Application

	/*
	* This is a simple server application
	* This server receive a string message from the Android mobile phone
	* and show it on the console.
	* Author by Lak J Comspace
	*/
	package simpleserver;
	import java.io.BufferedReader;
	import java.io.IOException;
	import java.io.InputStreamReader;
	import java.net.ServerSocket;
	import java.net.Socket;
	public class Main {
	private static ServerSocket serverSocket;
	private static Socket clientSocket;
	private static InputStreamReader inputStreamReader;
	private static BufferedReader bufferedReader;
	private static String message;
	public static void main(String[] args) {
	try {
	serverSocket = new ServerSocket(4444); //Server socket
	} catch (IOException e) {
	System.out.println("Could not listen on port: 4444");
	}
	System.out.println("Server started. Listening to the port 4444");
	while (true) {
	try {
	clientSocket = serverSocket.accept(); //accept the client connection
	inputStreamReader = new InputStreamReader(clientSocket.getInputStream());
	bufferedReader = new BufferedReader(inputStreamReader); //get the client message
	message = bufferedReader.readLine();
	System.out.println(message);
	inputStreamReader.close();
	clientSocket.close();
	} catch (IOException ex) {
	System.out.println("Problem in message reading");
	}
	}
	}
	}

view raw main.java hosted with ❤ by GitHub

Roman Number Converter - Java Program

This is a simple Java program to convert Roman numbers to Hindu-Arabic numbers. This Java method "convertRomToInt()" gets the Roman number as a string and converts it in to corresponding Integer value.
Even though this program seems simple, the algorithm is bit complex. When we convert a Roman number to Hindu-Arabic number manually, we do it in the following manner.

MCMXLIV = 1000 + (1000 − 100) + (50 − 10) + (5 − 1) = 1944

Value of each number is added together. When smaller values precede larger values, the smaller values are subtracted from the larger values, and the result is added to the total.
This algorithm use above technique to the conversion. "for" loop gets each character of the roman number string from the beginning and gets its integer value from the "getInt()"  method. At each iteration character is compared with the next character value. If the next character is the same, the value is added to mediator to add in the next iteration. If it is large, the value is added to mediator to subtract in the next iteration.

	//Converting Roman number to Arabic number
	public static int convertRomToInt(String romanNum) {
	int result = 0;
	int mediator = 0;
	int length = romanNum.length(); //get number string length
	for (int i = 0; i < length - 1; i++) { //this loop will add each Roman character value
	if (getInt(romanNum.charAt(i)) > getInt(romanNum.charAt(i + 1))) {
	result = result + getInt(romanNum.charAt(i)) + mediator;
	mediator = 0;
	} else if (getInt(romanNum.charAt(i)) == getInt(romanNum.charAt(i + 1))) {
	mediator = mediator + getInt(romanNum.charAt(i));
	} else if (getInt(romanNum.charAt(i)) < getInt(romanNum.charAt(i + 1))) {
	mediator = -mediator - getInt(romanNum.charAt(i));
	}
	}
	result = result + mediator + getInt(romanNum.charAt(length - 1));
	return result;
	}
	//Get integer value for corresponding Roman character
	public static int getInt(char romanChar) {
	if (romanChar == 'I')
	return 1;
	else if (romanChar == 'V') {
	return 5;
	} else if (romanChar == 'X') {
	return 10;
	} else if (romanChar == 'L') {
	return 50;
	} else if (romanChar == 'C') {
	return 100;
	} else if (romanChar == 'D') {
	return 500;
	} else if (romanChar == 'M') {
	return 1000;
	}
	return (Integer) null;
	}

view raw RomanNumberConverter.java hosted with ❤ by GitHub

GSM, GPRS, EDGE, WCDMA and HSPA

         
                Today I am going to discuss about something which you are really familiar. If you are using any wireless modem or mobile phone you may have used these words. But most of the people don’t have a clear idea what those technical acronyms stand for even though they frequently use it.

GSM
Global System for Mobile Communications (GSM) is a digital cellular phone technology. This includes set of standers to support the 2G digital cellular networks. 2G is the replacement of first generation analog cellular networks. GSM operates with TDMA (Time Division Multiple Access) technology based on circuit switching network. TDMA technology interleaves multiple digital signals on to high speed data channel. GSM supports voice calls and data transfer (SMS) speed up to 9.6kbit/s. Today GSM networks have spread over 218 countries worldwide and it allows the international roaming capability.
Mobile phone or any device which supports GSM technology includes a SIM (Subscriber Identity Module) card. This smart card has programmed so that it contains the details of the user account information.


GPRS
General Packet Radio Service (GPRS) is an improved data service in GSM networks. GPRS added a packet data transfer capability to circuit switched GSM networks. GPRS enables data rate up to 40 kbit/s. MMS, instant messaging and WAP are few services are offered by GPRS technology. 2G cellular technology together with GPRS is sometimes called 2.5G which described as a transition of 2G to 3G mobile telephony.


EDGE
Enhanced Data rates for GSM Evolution (EDGE) is a further enhancement of GPRS and GSM network technologies. EDGE is four times efficient than GPRS technology. GPRS uses four coding schemes (CS-1 to 4) while EDGE uses nine modulation and coding schemes (MCS-1 to 9). The normal data rate of EDGE is 40-50 kbps per timeslot and maximum is 40-50 kbps per timeslot. EDGE technology supports both circuit and packet switching techniques. EDGE technology can provides all the capabilities of the GPRS and directly map with the structure of the GSM network. Therefore EDGE is called backward compatible technology. No any changes are required for the existing GSM network for use of EDGE except the installation of EDGE transceiver at base stations. EDGE is only a software upgrade with GSM technology. EDGE cannot work without GSM technology, because EDGE networks are built upon the GSM networks. EDGE has all the requirement for the 3G standers and it is accepted as a 3G network technology.

WCDMA
Wideband Code Division Multiple Access (WCDMA) is a third generation (3G) cellular network technology. This technology has much higher data speed than the previous technologies which has described above. The data rates of the WCDMA technology are 2 Mbps for local area networks and 384 kbps for wide area networks. Even though it uses the same cored network as the GSM/GPRS/EDGE, WCDMA transmits on a pair of 5 MHz wide radio channels. WCDMA works with both frequency division duplex (FDD) and time division duplex (TDD). WCDMA provides mobile multimedia services such as music, tv/video image and internet access in addition to the voice, text and MMS services.

HSPA
High Speed Packet Access (HSPA) is a mobile wireless technology which represents the 3.5G family. HSPA is a combination of HSDPA (High Speed Downlink Packet Access) and HSUPA (High Speed Uplink Packet Access)  technologies. HSPA uses FDD transmission scheme. HSPA rates are 1 to 4 Mbps and HSPA uplink speeds are 500 kbps to 2 Mbps. But theoretically peak speed of downlink is 14 Mbps and the peak speed of uplink is 5.8 Mbps in a 5 MHz channel. HSPA is backward-compatible with UMTS, EDGE and GPRS. Besides the speed the advantage of the HSPA is the low cost of transmission for a data unit.