Execute stored procedure in spring with return value and out parameters

Following code example shows how to execute stored procedure in spring with return value and out parameters. The comment along with the code explains the usage.

import java.math.BigDecimal;
import java.sql.Types;
import java.util.HashMap;
import java.util.Map;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.SqlOutParameter;
import org.springframework.jdbc.core.SqlParameter;
import org.springframework.jdbc.core.simple.SimpleJdbcCall;

public class StoredProcedureExampleDAO extends SimpleJdbcCall {

 public JdbcDequeueTicketDAO(final JdbcTemplate jdbcTemplate) {
  super(jdbcTemplate);
  // Here declare all the IN and OUT parameters defined for the stored
  // procedure
  declareParameters(new SqlParameter("CountryCode", Types.VARCHAR),
    new SqlOutParameter("CountryName", Types.VARCHAR));
  // Register the stored procedure name
  withProcedureName("getCountryName");
  // This ensures the stored procedure return value also gets populated    
  // in the returned Map with key "return".
  withReturnValue();
 }
 
 public final String getCountryName(final String countryCode) {
  // Map to send the IN params values.
  Map inParams = new HashMap();
  inParams.put("CountryCode", countryCode);

  // Map for the OUT params and return value.
  Map outParams = null;
  try {
   outParams = execute(inParams);   
  } catch (Throwable t) {
   throw new DataAccessException("Failed to get the country name", t);
  }  
  if (null != outParams) {
   BigDecimal returnValue = (BigDecimal) outParams.get("return");
   // The logic of getCountryName stored procedure is that its 
   // returns 1 if execution is successful otherwise returns 0.
   if (null != returnValue && 1 == returnValue.intValue()) {
   // On success read the CountryName value
    String countryName = (String) outParams.get("CountryName");
    return countryName;
   }
   }
  throw new DataAccessException("Failed to get the country name");
 }

}

Logging using Aspect Oriented Programming

Most of the time while debugging I like to see the values of the incoming parameters and what is the returned value. The only solution is to use Eclipse debugger but some times its always not possible to run eclipse debugger. For example, the application is running in some environment where you cannot connect or sometimes you want to check quickly by just switching on DEBUG level logging.

Today I used Aspect Oriented Programming (AOP) to log incoming parameters and return value of a method execution. There are multiple ways but I like the following approach -

Ensure that required log4j and aspect jars are in the classpath of your project. The log4j is properly configured and gets initialized. If don't want to use log4j then in the MethodLogger class replace the log4j related code with whatever you require.

First create the following annotation which will be used against those methods for which logging is required -

public @interface LogMethod {
}

Now create following Aspect class in your source code. The comments explain the logic.

import org.apache.log4j.Logger;
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.annotation.AfterReturning;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;

// The Aspect annotation makes this class an Aspect
@Aspect
public class MethodLogger {

 // The Before annotation ensures beforeMethod is called before the 
 // execution of a method annotated by LogMethod.
 @Before(value = "@annotation(LogMethod)")
 public void beforeMethod(JoinPoint joinPoint) throws Throwable {
  // This ensures that the logger is of the actual class. If %c 
  // pattern is used in log4j then the class name of the actual 
  // method will print.
  Logger logger = Logger.getLogger(joinPoint.getTarget().getClass());
  if (logger.isDebugEnabled()) {
   StringBuilder builder = new StringBuilder();
   // Here we print the name of the method
   builder.append(joinPoint.getSignature().getName());
   builder.append("(");
   // Here we print the values of the method arguments
   appendArgumentValues(builder, joinPoint.getArgs());
   builder.append(")");

   logger.debug(builder.toString());
  }
 }

 // The AfterReturning annotation ensures afterReturningMethod 
 // is after the execution of a method annotated by LogMethod.
 @AfterReturning(value = "@annotation(LogMethod)", returning = "returnValue")
 public void afterReturningMethod(JoinPoint joinPoint, Object returnValue)
   throws Throwable {
  Logger logger = Logger.getLogger(joinPoint.getTarget().getClass());
  if (logger.isDebugEnabled()) {
   StringBuilder builder = new StringBuilder();
   builder.append(joinPoint.getSignature().getName());
   builder.append("(");
   // This prints the method argument class type
   appendArguments(builder, joinPoint.getArgs());
   builder.append("):");
   // This prints the return value of the method. Incase of void 
   // it prints null
   builder.append(returnValue);

   logger.debug(builder.toString());
  }
 }

 private void appendArguments(StringBuilder builder, Object[] objects) {
  for (Object obj : objects) {
   builder.append(obj.getClass().getName()).append(",");
  }

  if (objects.length > 0) {
   builder.deleteCharAt(builder.length() - 1);
  }
 }

 private void appendArgumentValues(StringBuilder builder, Object[] objects) {
  for (Object obj : objects) {
   builder.append(obj).append(",");
  }

  if (objects.length > 0) {
   builder.deleteCharAt(builder.length() - 1);
  }
 }
}

SpringSource Tool Suite

I have started using STS for the past 3-4 months. The tool is powered by the latest Eclipse version Galileo and comes bundled with useful plugins for Spring based development. The tool also comes with the maven plugin bundled in. I always use Maven and Spring for all my Java projects so I am enjoying this tool.

The suite also comes with Apache Tomcat server called TC Server. The server comes with a web application named "Insight". This web application tracks performance of the web applications deployed in this server. The application have a nice UI to drill down the statistics to pin point the code hampering the performance. No doubt the tool is very helpful to debug the code and find the performance bottlenecks. The beauty is no configurations are required at all.

SAXParser usage code sample

How to Parse XML in Java is always a tricky question. There different types of parsers available mainly - DOMParser (JDOM, Dom4j, XOM, etc.), SAXParser (Xerces, Piccolo, etc) and StAXParser (XPP3, Woodstox, Aalto, etc). Depending upon the nature and requirement of the project you need to select the type of parser.

Normally StAX Parsers also known as Pull Parsers are the fastest in terms of processing any size XML. The implementations available today don't support XSD validations. Some implementations support DTD validation only. StAX parsers also provide API to create an XML.

SAX Parsers also know as Push Parsers are the next best in terms of performance. Most of the implementations support XSD as well as DTD validations.

DOM Parsers are also fast but have memory overhead as it builds the whole XML tree in memory. Most of the implementations support XSD as well as DTD validations. The benefit of DOM is when you need to play with small size XMLs, need to read back and forward, change the XML and output new XML, etc. DOM parser also comes with good API support to traverse the XML compared to the handler implementation one need to do in case of SAX and StAX Parsers.

I required to parse a huge XML file and also validate against the defined XSD. I choose SAX parser because DOM have memory overhead and StAX doesn't support XSD validation. I have used Sun JDK6 provided Xerces implementation of SAX parser.

Here is the code snippet which parse the XML as well as validate. The comments in the code explains the functionality.

import java.io.File;
import java.io.IOException;
import javax.xml.XMLConstants;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import javax.xml.validation.Schema;
import javax.xml.validation.SchemaFactory;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

public class SAXXMLValidator {
 private SAXParser saxParser;

 public SAXXMLValidator(String schemaFilePath) throws SAXException,
   ParserConfigurationException {
  // Creates a schema factory object for the XSD validation
  SchemaFactory schemaFactory = SchemaFactory
    .newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);

  // schemaFilePath is the abosulte path, you can use any other way of providing the file.
  Schema schema = schemaFactory.newSchema(new File(schemaFilePath));
  SAXParserFactory saxParserFactory = SAXParserFactory.newInstance();

  // Set validating as false as this only validates against the DTD mentioned in the XML document.
  saxParserFactory.setValidating(false);

  // If your XSD uses namespace then set this to true otherwise you will get error like this "cvc-elt.1: Cannot find the declaration of element 'project'"
  saxParserFactory.setNamespaceAware(true);

  // Provide the schema to the factory for the parser to validate the XML
  saxParserFactory.setSchema(schema);

  // Creates a SAXParser and its thread safe so best to initialize all this in Constructor to save creation cost at the time of call
  saxParser = saxParserFactory.newSAXParser();
 }

 public void validate(String xmlFilePath, DefaultHandler defaultHandler)
   throws SAXException, IOException {
  // xmlFilePath is the abosulte path, you can use any other way of providing the file.
  // Extend the DefaultHandler to create your own handler to parse the XML and collect the errors as DefaultHandler already implements ErrorHandler.
  saxParser.parse(new File(xmlFilePath), defaultHandler);
 }

 public static void main(String[] args) {
  try {
   // I am using maven xsd and pom to test the code
   SAXXMLValidator saxxmlValidator = new SAXXMLValidator(
     "D:\\maven-v4_0_0.xsd");
   saxxmlValidator.validate("D:\\pom.xml", new DefaultHandler());
  } catch (SAXException e) {
   e.printStackTrace();
  } catch (ParserConfigurationException e) {
   e.printStackTrace();
  } catch (IOException e) {
   e.printStackTrace();
  }
 }
}

Configure Log4j for a web application on Apache Tomcat

Today I stumbled upon a problem of configuring log4j for a web application on Apache Tomcat. The problem is where to keep the log4j.xml and how initialize the logging system. One way is to keep the log4j.xml anywhere and change the Tomcat startup script to add -Dlog4j.configuration=<log4j.xml file path> but I do not want to depend on a change in Tomcat startup script.

I tried all the possible places but it did not work. I realized unless I define the log4j.configuration system parameter it will not work. I then looked at log4j api and found DOMConfigurator class which initializes the log4j system from log4j.xml.

Here is what I done to keep all configurations inside my application.

Create a listener class as shown below to initialize the log4j using the log4j.xml deployed with your application.

import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import org.apache.log4j.Logger;
import org.apache.log4j.xml.DOMConfigurator;

public class Log4jInitializationListener implements ServletContextListener {
    public Log4jInitializationListener() {
    }
    public void contextInitialized(ServletContextEvent servletContextEvent) {
DOMConfigurator.configureAndWatch(servletContextEvent.getServletContext().getInitParameter("log4jXMLFilePath"));
        Logger logger = Logger.getLogger(Log4jInitializationListener.class);
        logger.debug("Log4j working");
    }

    public void contextDestroyed(ServletContextEvent servletContextEvent) {
    }
}

Add these entries to your web.xml. Here we are defining a parameter to configure the log4j.xml file path and registering the above created listener.

<pre>
<context-param>
<param-name>log4jXMLFilePath</param-name>
<param-value>WEB-INF/classes/log4j.xml</param-value>
</context-param>
<listener>
<listener-class>Log4jInitializationListener</listener-class>
</listener>
</pre>

Start the application to confirm log4j is working. I have used the following log4j configuration so here it creates a server.log file.

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">
<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/" debug="false">
 <appender name="RollingFileAppender" class="org.apache.log4j.RollingFileAppender">
  <param name="File" value="server.log"/>
  <param name="MaxFileSize" value="100MB"/>
  <param name="MaxBackupIndex" value="10"/>
  <layout class="org.apache.log4j.PatternLayout">
   <param name="ConversionPattern" value="%d [%t] %-5p %l - %m%n" />
  </layout>
 </appender>
 <root>
  <priority value="debug"/>
  <appender-ref ref="RollingFileAppender"/>
 </root>
</log4j:configuration>

Project Euler Problem 5

Problem 5

2520 is the smallest number that can be divided by each of the numbers from 1 to 10 without any remainder.

What is the smallest number that is evenly divisible by all of the numbers from 1 to 20?

public class ProblemFive {
    public static void main(String[] args) {
        // Any number will be always divisible by 1
        // To be divisible by 2 it has to be an even number
        // Number will be greater than or equal to at least 20
        int start = 20;

        while (true) {
            int i = 3;

            for (; i <= 20; ++i) {
                if (0 != (start % i)) {
                    break;
                }
            }

            if (i >= 20) {
                break;
            }

            start += 2;
        }

        System.out.println(start);
    }
}

RIA frameworks compared

Web based application having desktop like GUI is popularly known as RIA (Rich Internet Application). In old days only few solutions were available namely Java applet, Flash, Dynamic html, etc. Nowadays there are loads of frameworks which provide desktop like experience. These frameworks are based on AJAX (Asynchronous JavaScript + XML) technology.

The choices of RIA frameworks are huge and it's difficult to choose the most suitable for your need. The best part of open source technology is for every problem there are numerous solutions, but the worst part is choosing the right technology for your need.

I found these available frameworks to build RIA - Adobe Flex, extJS, Jboss Richfaces, IceFaces, Oracle ADF, JavaFX, Silverlight, GWT, IT Mill Toolkit, ZK, OpenLaszlo, BackBase, Echo, Morfik, Haxe, YUI, pyjamas, DWR, Prototype, Curl, SproutCore, Cappuccino, jQuery, etc.

A selection criterion needs to be defined to select a suitable framework. I choose these criteria -

Popularity of the framework - The framework should be popular in developer community. Popularity brings good publications, community support, improvements, etc.

Support - A framework should have a good support in terms of books, training facilities, mailing lists, etc.

Out-of-the-box GUI components - A framework should provide ready to use components to save time in building basic blocks.

Underlying technology - Underlying technology is also important to check the learning curve, effort required, developer expertise, etc.

After applying the above criteria, I am left with extJS, Flex, GWT and Silverlight. These frameworks provide rich look and feel and have loads of ready to use components.

extJS
It's a cross browser Java Script library for building RIA.

Advantages

Huge set of rich widgets.

Good API documentation available.

Disadvantages

It's not free.

JavaScript knowledge required.

No good support for Web Service.

To do simple things, lot of JavaScript coding required.

CSS customization is not easy.

Firebug debugging is of no use as the generated html is bad.

Adobe Flex
Flex is a highly productive, free open source framework for building and maintaining expressive web applications that deploy consistently on all major browsers, desktops, and operating systems.

Advantages

Best look and feel.

Rich design and multimedia as its flash.

Easy to deploy.

Flex Builder IDE to develop UI using drag and drop.

Open source.

Web service integration is very easy.

Desktop application can be also developed.

Disadvantages

Flex Builder is not free.

Knowledge of MXML and ActionScript required.

Requires Plugin installation on the client side.

Browser history support not possible.

Rendering flash is still slow.

RPC calls are cumber some and need third party software like BlazeDS.

GWT (Google Web Toolkit)
Writing web apps today is a tedious and error-prone process. Developers can spend 90% of their time working around browser quirks. In addition, building, reusing, and maintaining large JavaScript code bases and AJAX components can be difficult and fragile. Google Web Toolkit (GWT), especially when combined with the Google Plugin for Eclipse, eases this burden by allowing developers to quickly build and maintain complex yet highly performant JavaScript front-end applications in the Java programming language.

Advantages

Developer need to know only Java. No JavaScript.

Huge choices of ready to use components.

Eclipse IDE support to develop.

Code can be debugged in Eclipse.

Eclipse hosted mode available for hot deployment.

Look and feel is good and can be easily customized using CSS.

Maven supported so builds are easy.

Junit test cases to test the code.

Easy Web Service configuration based on annotations.

Similar to Java Swing.

Loads of active mailing lists to seek solution.

Doesn't require Plugin installation on the client side.

GWT is free so no cost.

Browser history support works.

Disadvantages

Only for Java developers.

Compiling Java to JavaScript is very slow.

No drag and drop IDE available.

Desktop application cannot be developed.

Microsoft Silver light
Microsoft Silver light is a free runtime that powers rich application experiences and delivers high quality, interactive video across multiple platforms and browsers, using the .NET framework.

Advantages

.Net knowledge helps.

Visual Studio IDE support.

Desktop applications can be developed.

Disadvantages

Requires plugin installation on the client side.

Fairly new framework so wider support is not available.

Its not open source.

Project Euler Problem 4

Problem 4

A palindromic number reads the same both ways. The largest palindrome made from the product of two 2-digit numbers is 9009 = 91 99.

Find the largest palindrome made from the product of two 3-digit numbers.

The solution is to multiply each three digit number and check if its a palindrome or not.

public class ProblemFour {
    public static void main(String[] args) {
        int palindrome = 9009;

        for (int i = 999; i > 99; --i) {
            for (int j = i; j > 99; --j) {
                int product = i * j;

                if (isPalindrome(String.valueOf(product)) &&
                        (product > palindrome)) {
                    palindrome = product;
                }
            }
        }

        System.out.println(palindrome);
    }

    public static boolean isPalindrome(String data) {
        char[] array = data.toCharArray();
        int reverseIndex = array.length - 1;
        int index = 0;

        while (index < reverseIndex) {
            if (array[index] != array[reverseIndex]) {
                return false;
            }

            ++index;
            --reverseIndex;
        }

        return true;
    }
}

Hibernate OneToMany annotation mapping using JoinTable

Hibernate OneToMany annotation mapping using JoinTable

Recently I explored Hibernate OneToMany annotation mapping using JoinTable.

Consider an Airline entity having list of Airports. The mapping between the two is stored in a JoinTable airline_airports.

CREATE TABLE airline(
   code char(2) PRIMARY KEY NOT NULL,
   name varchar(50) NOT NULL
);

CREATE TABLE airport(
   code char(3) PRIMARY KEY NOT NULL,
   name varchar(50) NOT NULL
);

CREATE TABLE airline_airport(
   airline_code char(2) NOT NULL,
   airport_code char(3) NOT NULL,
   CONSTRAINT PRIMARY PRIMARY KEY (airline_code,airport_code)
);

ALTER TABLE airline_airport ADD CONSTRAINT airline_airport_ibfk_1
FOREIGN KEY (airline_code) REFERENCES airline(code) ON DELETE NO ACTION ON UPDATE NO ACTION;

ALTER TABLE airline_airport ADD CONSTRAINT airline_airport_ibfk_2
FOREIGN KEY (airport_code) REFERENCES airport(code) ON DELETE NO ACTION ON UPDATE NO ACTION;

First of all we need to create Hibernate Entities for Airline and Airport using annotations. Notice the annotations defined for airports attribute of Airline class. This is where we are defining the relationship between Airline and Airport.

@Entity
@Table(name = "airline")
public class Airline implements Serializable {
    @Id
    @Column(name = "code")
    private String code;
    @OneToMany(fetch=FetchType.EAGER, cascade=CascadeType.ALL)
    @JoinTable(name = "airline_airport", joinColumns = @JoinColumn(name = "airline_code")
    , inverseJoinColumns = @JoinColumn(name = "airport_code")
    )
    private List airports;

    public String getCode() {
        return code;
    }

    public void setCode(String code) {
        this.code = code;
    }

    public List getAirports() {
        return airports;
    }

    public void setAirports(List airports) {
        this.airports = airports;
    }
}

@Entity
@Table(name = "airport")
public class Airport implements Serializable {
    @Id
    @Column(name = "code")
    private String code;
    @Column(name = "name")
    private String name;

    public String getCode() {
        return code;
    }

    public void setCode(String code) {
        this.code = code;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

Create an Airline object and add a list of Airlines. When you will save the airline object, hibernate will persist all the data in airline, airport and airline_airport table.

If you don't use the cascade annotation then ii will not save the data in airport table. This means it will fail to insert record in airline_airport table if an airport is not already in the airport table.

Benefits of GWT

After evaluating and reading various Rich Internet Application solutions, I have finally selected GWT and GWT-Ext.

I developed a prototype using GWT 1.6.4, GWT-Ext 2.0.5, GWTRPC-spring 1.01 on Tomcat 6.0.18 with back end in Spring 2.5.6 and Hibernate 3.3.1.

I kept the architecture simple and separate layers by developing UI in GWT and business logic in Spring beans. As you know the whole GWT UI runs in user browser and Spring beans running in Tomcat. GWT Async architecture is used to interact with Spring beans. GWT converts the Java code into Javascript at deploy time.

I finalized GWT based on these parameters -

• Only Java knowledge is required.


• Team is accustomed to Eclipse so this was an advantage for us.


• Ability to use Java Debugger in Eclipse is extremely helpful.


• GWT Hosted mode in eclipse, so no compile and deploy required on every change.
  
• Big developer community.


• Lots of ready to use components.


• Prior Java knowledge helpful.


• Similar to swing and the team have worked on Swing in earlier project.


• Look and feel is good.


• Maven support is also available.


• Can write Junit test cases.


• Easy RPC configuration based on annotations.

GWT with maven and eclipse

Setting up a latest GWT project in eclipse along with Maven was not straight forward. Here is step-by-step guide on how I managed to setup my environment.

I assume you have Eclipse installed with m2eclipse plugin. Also Maven installed and its maven executable is in your environment PATH.

Run the below maven archetype to create a project shell. I named my project gwttest.

mvn archetype:create -DarchetypeGroupId=com.totsp.gwt -DarchetypeArtifactId=maven-googlewebtoolkit2-archetype -DarchetypeVersion=1.0.4 -DgroupId=com.gwttest -DartifactId=gwttest

The above command will create a directory "gwttest".

In the generated pom.xml, change the gwt version to the version you are using. The version should be available in the maven repository. I used latest GWT version 1.6.4. Also remove the pluginRepositories and unpack plugin from the pom.xml as that it is not required.

Create an Application.launch file in your project with the below content. Launch file is required to run the project from Eclipse.

<?xml version="1.0" encoding="UTF-8"?>
<launchConfiguration type="org.eclipse.jdt.launching.localJavaApplication">
<booleanAttribute key="org.eclipse.jdt.launching.DEFAULT_CLASSPATH" value="false"/>
<listAttribute key="org.eclipse.jdt.launching.CLASSPATH">
<listEntry value="<?xml version="1.0" encoding="UTF-8"?>
<runtimeClasspathEntry containerPath="org.eclipse.jdt.launching.JRE_CONTAINER" javaProject="gwttest" path="1" type="4"/>
"/>
<listEntry value="<?xml version="1.0" encoding="UTF-8"?>
<runtimeClasspathEntry internalArchive="gwttest/src/main/java" path="3" type="2"/>
"/>
<listEntry value="<?xml version="1.0" encoding="UTF-8"?>
<runtimeClasspathEntry id="org.eclipse.jdt.launching.classpathentry.defaultClasspath">
<memento project="gwttest"/>
</runtimeClasspathEntry>
"/>
</listAttribute>
<stringAttribute key="org.eclipse.jdt.launching.PROJECT_ATTR" value="gwttest"/>
<stringAttribute key="org.eclipse.jdt.launching.MAIN_TYPE" value="com.google.gwt.dev.HostedMode"/>
<stringAttribute key="org.eclipse.jdt.launching.PROGRAM_ARGUMENTS" value="-war target\gwttest-1.0-SNAPSHOT com.gwttest.Application"/>
<stringAttribute key="org.eclipse.jdt.launching.VM_ARGUMENTS" value="-Xmx256M"/>
<booleanAttribute key="org.eclipse.debug.core.appendEnvironmentVariables" value="true"/>
</launchConfiguration>

In Eclipse go to File > Import > General > Maven Projects. Select the directory "gwttest" and finish.

To generate a war file right click on the project > Run As > Maven package. The war file will be created under gwttest\target folder.

To test right click on the Application.launch file > Run As > Application. The sample GWT application will start in hosted mode.

To debug right click on the Application.launch file > Debug As > Application.

Maven web application

As mentioned in my POC, I used maven to develop the sample application.

You need latest maven installed on your system.

Execute this command to create a web application structure.

mvn archetype:create -DgroupId=com.travel -DartifactId=travel -DarchetypeArtifactId=maven-archetype-webapp

Replace the pom.xml with this xml. This is the final pom of my POC. Notice the exclusion of asm and cglib libraries in hibernate dependency and explicitly defining asm version 2.2.3 and cglib 2.1_3. It's because there was confict between asm library versions required by hibernate and cxf.

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.travel</groupId>
  <artifactId>travel</artifactId>
  <packaging>war</packaging>
  <version>1.0-SNAPSHOT</version>
  <name>travel Maven Webapp</name>
  <url>http://maven.apache.org</url>
  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
    <dependency>
     <groupId>org.hibernate</groupId>
     <artifactId>hibernate-core</artifactId>
     <version>3.3.1.GA</version>
     <exclusions>
   <exclusion>
    <groupId>asm</groupId>
    <artifactId>asm</artifactId>
   </exclusion>
   <exclusion>
    <groupId>asm</groupId>
    <artifactId>asm-attrs</artifactId>
   </exclusion>
   <exclusion>
    <groupId>cglib</groupId>
    <artifactId>cglib</artifactId>
   </exclusion>
  </exclusions>
    </dependency>
    <dependency>
     <groupId>asm</groupId>
     <artifactId>asm</artifactId>
     <version>2.2.3</version>
    </dependency>
    <dependency>
     <groupId>cglib</groupId>
     <artifactId>cglib-nodep</artifactId>
     <version>2.1_3</version>
    </dependency>
    <dependency>
     <groupId>org.hibernate</groupId>
     <artifactId>hibernate-annotations</artifactId>
     <version>3.3.1.GA</version>
     <exclusions>
   <exclusion>
    <groupId>asm</groupId>
    <artifactId>asm</artifactId>
   </exclusion>
   <exclusion>
    <groupId>asm</groupId>
    <artifactId>asm-attrs</artifactId>
   </exclusion>
   <exclusion>
    <groupId>cglib</groupId>
    <artifactId>cglib</artifactId>
   </exclusion>
  </exclusions>
    </dependency>
    <dependency>
     <groupId>mysql</groupId>
     <artifactId>mysql-connector-java</artifactId>
     <version>5.1.6</version>
     <scope>provided</scope>
 </dependency>
 <dependency>
  <groupId>org.springframework</groupId> 
  <artifactId>spring</artifactId> 
  <version>2.5.6.SEC01</version> 
 </dependency>
 <dependency>
  <groupId>org.apache.cxf</groupId> 
  <artifactId>cxf-rt-core</artifactId> 
  <version>2.2.1</version> 
 </dependency>
 <dependency>
  <groupId>org.apache.cxf</groupId> 
  <artifactId>cxf-rt-frontend-jaxws</artifactId> 
  <version>2.2.1</version> 
 </dependency>
 <dependency>
  <groupId>org.apache.cxf</groupId> 
  <artifactId>cxf-rt-transports-http-jetty</artifactId> 
  <version>2.2.1</version> 
 </dependency>
  </dependencies>
  <build>
    <finalName>travel</finalName>
   <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>2.0.2</version>
        <configuration>
          <source>1.5</source>
          <target>1.5</target>
        </configuration>
      </plugin>
    </plugins>
  </build>
</project>

After this you can import this project in Eclipse. Go to File > Import > General > Maven Projects. For this m2eclipse plugin needs to be installed in your Eclipse.

Apache cxf using annotations and integration with Spring

Today I will show you how you can create a webservice using Apache CXF version 2.2.1. I will be building this webservice on top of my previous application.

Create a interface AirlineManager to expose methods over webservice. The create method takes airline code and name to create a Airline record in database. Annotation @WebService tells that this is a interface for webservice.

package com.travel;

import javax.jws.WebService;

@WebService
public interface AirlineManager {
    public void create(String code, String name);
}

Implement the above webservice interface. We are using AirlineDao created in earlier post. Notice the @WebService(endpointInterface = "com.travel.AirlineManager") which tells that this implementation is for AirlineManager interface.

package com.travel;

import com.travel.dao.AirlineDao;
import javax.jws.WebService;

@WebService(endpointInterface = "com.travel.AirlineManager")
public class AirlineManagerImpl implements AirlineManager {
    private AirlineDao airlineDao;

    public AirlineManagerImpl(AirlineDao aAirlineDao) {
        airlineDao = aAirlineDao;
    }

    @Override
    public void create(String code, String name) {
        airlineDao.create(code, name);
    }
}

Add this in the spring-context.xml. Here we are importing some cxf beans, defining bean AirlineManagerImpl and creating airlineManagerService webservice.

 <import resource="classpath:META-INF/cxf/cxf.xml" />
 <import resource="classpath:META-INF/cxf/cxf-extension-soap.xml" />
 <import resource="classpath:META-INF/cxf/cxf-extension-http-jetty.xml"/>
 <import resource="classpath:META-INF/cxf/cxf-servlet.xml" />

 <bean id="airlineManager" class="com.kaleconsultants.travel.AirlineManagerImpl">
  <constructor-arg><ref bean="airlineDao"/></constructor-arg>
 </bean>

 <jaxws:endpoint id="airlineManagerService" implementor="#airlineManager" address="/AirlineManagerService" />

Add this in your web.xml.

 <servlet>
  <servlet-name>CXFServlet</servlet-name>
  <display-name>CXF Servlet</display-name>
  <servlet-class>
   org.apache.cxf.transport.servlet.CXFServlet
  </servlet-class>
  <load-on-startup>1</load-on-startup>
 </servlet>
  
 <servlet-mapping>
  <servlet-name>CXFServlet</servlet-name>
  <url-pattern>/*</url-pattern>
 </servlet-mapping>

Deploy the application in tomcat and your webservice is ready. You can check the wsdl http://host:port/travel/AirlineManagerService?wsdl.

To test the webservice, you need to create a client. You can use wsdl2java available in the bin directory of cxf.

Execute this command, this will generate the wsdl stubs.
wsdl2java http://host:port/travel/AirlineManagerService?wsdl

Write a client like this and there you go.......

package com.travel;

public class ClientTest {
    public static void main(String[] args) {
        AirlineManagerImplService service = new AirlineManagerImplService();
        AirlineManager airlineManager = service.getAirlineManagerImplPort();
        airlineManager.create("IC", "Indian");
    }
}

Hibernate integration with Spring

In my last post Basic Hibernate Annotations example, I wrote about a simple hibernate example. Today I will take that example forward and show you how you can integrate hibernate with Spring. I used Spring version 2.5.6.SEC01.

Create spring-context.xml file. We define a spring datasource, hibernate session factory, hibernate template(spring wrapper api of hibernate session), transaction manager. Bean airlineDao is configured to use annotation based transaction handling. The "<tx:annotation-driven/>" actually enables Spring container to execute methods under transaction, if transaction annotations are used.

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans" 
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xmlns:tx="http://www.springframework.org/schema/tx"
 xsi:schemaLocation="
 http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
 http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.5.xsd">

 <bean id="dataSource" class="org.springframework.jndi.JndiObjectFactoryBean">
  <property name="jndiName" value="java:comp/env/jdbc/travel"/>    
  <property name="resourceRef" value="true" /> 
 </bean>

 <bean id="sessionFactory" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
  <property name="dataSource"><ref bean="dataSource"/></property>
  <property name="configLocation"><value>classpath:hibernate.cfg.xml</value></property>
  <property name="configurationClass"><value>org.hibernate.cfg.AnnotationConfiguration</value></property>
 </bean>

 <bean id="hibernateTemplate" class="org.springframework.orm.hibernate3.HibernateTemplate">
     <property name="sessionFactory"><ref bean="sessionFactory"/></property>
 </bean>

 <bean id="transactionManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager">
     <property name="sessionFactory"><ref bean="sessionFactory"/></property>
 </bean>

 <tx:annotation-driven/>
 
 <bean id="airlineDao" class="com.travel.dao.AirlineDao">
  <property name="hibernateTemplate"><ref bean="hibernateTemplate"/></property>
 </bean>
</beans>

Create AirlineDao class. Notice the @Transactional (readOnly = true) annotation which brings the execution of this class under transaction. The create method have (readOnly = false) because in this method we are actually updating the table.

package com.travel.dao;

import com.travel.domain.Airline;
import org.springframework.orm.hibernate3.support.HibernateDaoSupport;
import org.springframework.transaction.annotation.Transactional;
import java.util.List;

@Transactional (readOnly = true)
public class AirlineDao extends HibernateDaoSupport {
    @Override
    @Transactional (readOnly = false)
    public void create(String code, String name) {
        Airline airline = new Airline();
        airline.setCode(code);
        airline.setName(name);
        getHibernateTemplate().save(airline);
    }
}

Add the below xml in your web.xml. This Spring ContextLoaderListener initializes the spring beans defined in file spring-context.xml (we created above).

  <context-param>   
    <param-name>contextConfigLocation</param-name>   
    <param-value>/WEB-INF/classes/spring-context.xml</param-value>   
  </context-param>   
     
  <listener>   
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>   
  </listener>

Create a simple servlet to test the DAO. The execution of this servlet will create a new airline record in airline table.

package com.travel.servlet;

import com.kaleconsultants.travel.dao.AirlineDao;
import org.springframework.context.ApplicationContext;
import org.springframework.web.context.support.WebApplicationContextUtils;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class AirlineServlet extends HttpServlet {
    private static final long serialVersionUID = 2409603422056073641L;

    protected void service(HttpServletRequest request,
        HttpServletResponse response) throws ServletException, IOException {
     
     String code = request.getParameter("code");
     String name = request.getParameter("name");
     ApplicationContext context = WebApplicationContextUtils.getRequiredWebApplicationContext(getServletContext());
     AirlineDao airlineDao = (AirlineDao) context.getBean("airlineDao");
     airlineDao.create(code, name);
    }
}

Basic Hibernate Annotations example

As part of my POC, today I developed a simple hibernate annotations based example. To run this example, you need JDK 5.0 or higher and hibernate 3.2.0.GA or above. I am using JDK 1.6, MySql 5.1, Tomcat 6.0.18 and Hibernate 3.3.1.GA.

Create hibernate.cfg.xml file. This file should be available in the classpath at runtime. I developed this example as part of a web application and I am using a datasource defined in my container. See my earlier post on How to configure a datasource in Tomcat

<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
 <session-factory>
  <property name="connection.datasource">java:comp/env/jdbc/travel</property>
  <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
  <property name="current_session_context_class">thread</property>
  <property name="show_sql">true</property>
  <mapping class="com.travel.domain.Airline"/>
 </session-factory>
</hibernate-configuration>

This example needs following table in your database.

CREATE TABLE airline (
   code char(2) PRIMARY KEY,
   name varchar(50) NOT NULL,
   created timestamp  DEFAULT NOW() NOT NULL
);

Create HibernateUtil class which provides Hibernate session to interact with database. new AnnotationConfiguration().configure() looks for hibernate.cfg.xml in the classpath, so make sure to deploy the file in WEB-INF/classes directory.

package com.travel.hibernate.util;

import org.hibernate.SessionFactory;
import org.hibernate.cfg.AnnotationConfiguration;

public class HibernateUtil {
    private static final SessionFactory sessionFactory;

    static {
        try {
            sessionFactory = new AnnotationConfiguration().configure()
                                                          .buildSessionFactory();
        } catch (Throwable ex) {
            System.err.println("Initial SessionFactory creation failed." + ex);
            throw new ExceptionInInitializerError(ex);
        }
    }

    public static SessionFactory getSessionFactory() {
        return sessionFactory;
    }
}

Airline class maps with the airline table we created above. Notice the annotations used to define the mapping.

package com.travel.domain;

import java.io.Serializable;
import java.util.Date;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name = "airline")
public class Airline implements Serializable {
    private static final long serialVersionUID = 6864693643526282786L;
    @Id
    @Column(name = "code")
    private String code;
    @Column(name = "name")
    private String name;
    @Column(name = "created")
    private Date createdTime;

    public String getCode() {
        return code;
    }

    public void setCode(String code) {
        this.code = code;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Date getCreatedTime() {
        return createdTime;
    }
}

Simple servlet to test the application. I used the hibernate code directly in my servlet for simplicity. You should define one DAO layer to encapsulate the hibernate code. To test acccess your servelt use url like http://host:port/travel/AirlineServlet?code=LH&name=Lufthansa

package com.travel.servlet;

import com.travel.domain.Airline;
import com.travel.hibernate.util.HibernateUtil;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class AirlineServlet extends HttpServlet {
    private static final long serialVersionUID = 2409603422056073641L;

    protected void service(HttpServletRequest request,
        HttpServletResponse response) throws ServletException, IOException {
        SessionFactory session = HibernateUtil.getSessionFactory();
        Session sess = session.getCurrentSession();
        Transaction tx = sess.beginTransaction();
        // Get the airline code and name
        String airlineCode = request.getParameter("code");
        String airlineName = request.getParameter("name");
        // Create Airline object
        Airline  airline = new Airline();
        airline.setCode(airlineCode);
        airline.setName(airlineName);
        // Save the record in database
        sess.save(airline);
        tx.commit();
        session.close();
    }
}

How to configure a datasource in Apache Tomcat

I have to build a POC (proof of concept) using JDK6, Spring, Hibernate and Apache CXF on Apache Tomcat. I will be using Maven build tool and Nexus repository. My IDE is Eclipse with m2eclipse and spring IDE plugin. In a nutshell we need a webservice application and I have chosen these technologies to develop the solution. I thought it would be a good idea if I blog on how I developed this POC. I will do step-by-step development.

Lets start with "How to configure a datasource in Apache Tomcat".

There is another way of configuring datasource in Tomcat, but I prefer this solution as the configuration resides in the application war file. Simply copy your war file in a tomcat server along with the required jdbc jar and your application is up and running. I wish I can bundle the jdbc jar also in war but unfortunately it doesn't work.

Create a file name "context.xml" (any other name will not work) in META-INF directory of your war file. The content of the context.xml will look like this -

<Context path="/travel" debug="5" reloadable="true" crossContext="true">
  <Resource name="jdbc/travel" auth="Container" type="javax.sql.DataSource"
               maxActive="100" maxIdle="30" maxWait="10000"
               username="user" password="password" driverClassName="com.mysql.jdbc.Driver"
               url="jdbc:mysql://localhost:3306/travel?autoReconnect=true"/>
</Context>

Add this in the web.xml of your war -

<resource-ref>
  <description>Datasource</description>
  <res-ref-name>jdbc/travel</res-ref-name>
  <res-type>javax.sql.DataSource</res-type>
  <res-auth>Container</res-auth>
</resource-ref>

The res-ref-name should match the //Resource@name defined in the context.xml

Copy the required jdbc driver jar in $TOMCAT_HOME/lib directory. In this case its mysql-connector-java-5.1.6.jar for mysql database.

Project Euler Problem 3

Problem 3

The prime factors of 13195 are 5, 7, 13 and 29.

What is the largest prime factor of the number 600851475143 ?

The solution is to find a factor and check if its a prime number. Since we need largest prime factor, run the for loop in reverse direction. Also a prime factor of a number cannot be greater than the square root of the number.

public class ProblemThree {
    public static void main(String[] args) {
        long range = (long) Math.sqrt(600851475143L);

        for (long i = range; i > 1; --i) {
            if ((0 == (number % i)) && isPrimeNumber(i)) {
                System.out.println(i);

                break;
            }
        }
    }

    public static boolean isPrimeNumber(long number) {
        long halfRange = number / 2;

        for (long i = 2; i <= halfRange; ++i) {
            if (0 == (number % i)) {
                return false;
            }
        }

        return true;
    }
}

Rich Internet application

Web based application having desktop like GUI is popularly known as RIA(Rich Internet Application). I need to develop such a rich interactive web based application. In old days we used to have only few solutions - Java applet, Flash, Dynamic html. Nowadays there are loads of frameworks which provide desktop like experience. These frameworks are based on ajax technology.

I thought it would be easy to select the best framework for my need. But on the contrary the choices are many, that its difficult to choose. The best part of open source technology is for every problem there are numerous solutions. But the worst part is choosing the right technology for your need. I wish, I can find an easy comparison chart somewhere.

I did some search and found these frameworks - Adobe Flex, extJS, Jboss Richfaces, IceFaces, Oracle ADF, JavaFX, Silverlight, GWT, IT Mill Toolkit, ZK, OpenLaszlo, BackBase, Echo, Morfik, Haxe, YUI, pyjamas, DWR, Prototype. There could be many more frameworks available. Over the next few days I will be evaluating these list to find the popularity, support, out-of-the-box GUI components, underlying technology and any other parameter which helps in selecting few solutions. Once I am down to two or three solutions, I would like to develop a simple application to select the right solution.

Project Euler Problem 2

Today I got some time to look at Euler Problem 2.

Problem 2

Each new term in the Fibonacci sequence is generated by adding the previous two terms. By starting with 1 and 2, the first 10 terms will be:

1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...

Find the sum of all the even-valued terms in the sequence which do not exceed four million.

The solution is to run a loop to find the next term in Fibonacci series. Check the evenness of the term and add to the sum.

public class ProblemTwo {
    public static void main(String[] args) {
        int firstTerm = 0;
        int secondTerm = 1;
        int newTerm = 0;
        int sum = 0;

        while (secondTerm <= 4000000) {
            newTerm = firstTerm + secondTerm;

            if (0 == (newTerm % 2)) {
                sum += newTerm;
            }

            firstTerm = secondTerm;
            secondTerm = newTerm;
        }

        System.out.print(sum);
    }
}

Project Euler Problem 1

Recently I came across Project Euler web site. This is what the site has to say

"Project Euler is a series of challenging mathematical/computer programming problems that will require more than just mathematical insights to solve. Although mathematics will help you arrive at elegant and efficient methods, the use of a computer and programming skills will be required to solve most problems. The motivation for starting Project Euler, and its continuation, is to provide a platform for the inquiring mind to delve into unfamiliar areas and learn new concepts in a fun and recreational context."

I quickly registered to check what kind of mathematical problems are asked. I couldn't resist myself to start solving the problems. I chose Java to solve the problems as this is the only language I know ;)

Problem 1

If we list all the natural numbers below 10 that are multiples of 3 or 5, we get 3, 5, 6 and 9. The sum of these multiples is 23.
Find the sum of all the multiples of 3 or 5 below 1000.

The solution is very simple and the code is self explanatory.

public class ProblemOne {
    public static void main(String[] args) {
        int result = 0;

        for (int i = 1; i < 1000; ++i) {
            if ((0 == (i % 3)) || (0 == (i % 5))) {
                result += i;
            }
        }

        System.out.println(result);
    }
}

.equals Vs == in Java

Recently a Java developer asked for help in a J2EE application. He was stuck in a bug for the past two days. The development environment was Windows, Eclipse IDE and Tomcat server. He was using old mill fashion of debugging by adding System.out.println in his code. Before anything else I asked him to setup debugger in Eclipse. The debugger made his life easy and helped him quickly figure out the problem area. But he couldn't understand why a particular if condition not behaving correctly. As you can guess from the title of this blog, it was the same age old problem of == and .equals().

In Java == is used to compare variables of primitive data types (byte, short, int, long, float, double, boolean, char). If == is used to compare two objects then it compares the object reference and not the values. An object in Java stores the memory reference where the object data is stored. In order to compare the values you need to use object1.equals(object2). Lets learn the difference with simple example -

String s1 = new String("test");
String s2 = new String("test");

Here we have defined two String objects s1 and s2. Value of both the variable is same "test", so we expect the variables to be equal.

if (s1 == s2) {
  System.out.println("Strings are equal");
} else {
  System.out.println("Strings are not equal");
}

Surprised to see that it prints "Strings are not equal". Well its correct as both s1 and s2 are referring to two different memory references.

if (s1.equals(s2)) {
  System.out.println("Strings are equal");
} else {
  System.out.println("Strings are not equal");
}

The above code is correct way of comparing String values. This code will print "Strings are equal". Now consider this below code -

String s1 = "test";
String s2 = "test";

if (s1 == s2) {
  System.out.println("Strings are equal");
} else {
  System.out.println("Strings are not equal");
}

Another surprise, it prints "Strings are equal". Its because Java compiler does the optimization. Notice the way s1 and s2 are defined. In earlier code we used new String("test") which makes sure new object gets created. But in this code compiler uses the same reference to define the two variables.

== and .equals() usage holds true for objects of any class. Remember every Java class implicitly extends Object class. Most of the Java core classes like Integer, Long, Double, Boolean, etc have .equals() method implemented. For your own class don't forget to implement the .equals() otherwise .equals() will behave same as ==.

Configure Eclipse for Remote Debugging

A J2EE developer always finds it difficult to debug a web application. The developer has to rely on log4j logging to understand what is happening. Although exception stack trace provides valuable info but at times it's not enough to debug a problem. Even for a trivial problem sometimes debugging takes ages. What if a developer can follow the execution in real-time and able to see the flow, values assigned to the variables, etc. Well a Java debugger is there to make debugging comfortable and quick. My favorite Eclipse IDE provides the remote debugging with lots of useful features.

But first we need to know how to enable a JVM to be debugged remotely. Any application server like JBoss, Tomcat, Weblogic, etc. or a simple JVM instance can be debugged remotely. Pass the following arguments to a JVM to enable remote debugging.

-Xdebug -Xnoagent -Xrunjdwp:transport=dt_socket,address=8787,server=y,suspend=n

If both the debugger and target JVM is 5.0 and above then the preferred way is given below, although the above will also work.

-agentlib:jdwp=transport=dt_socket,address=8787,server=y,suspend=n

More information of Java debugger is available here

To enable Jboss or Tomcat for remote debugging, you need to set JAVA_OPTS environment variable with the above arguments. Start the server, the Java Debugger is ready to listen on the defined port.

Follow the below steps to configure Eclipse for debugging -

In Eclipse go to Run > Debug Configurations..., a popup will open.

Right click on "Remote Java Application" and select New.

Give some name so that you can identify this debugger.

Select a project which you want to debug.

Select "Standard (Socket Attach)" as Connection Type.

Provide the host and port details where the remote JVM is running. For the above example port number will be 8787.

Click on Debug and Eclipse will open the Debug perspective which provides lots of helpful features.

The first task to debug a problem is to set breakpoints in the code where you think the problem persists. Eclipse allows conditional breakpoints which gets triggered when the defined condition evaluates to true. At runtime value of a variable can be changed to debug the code. Another useful functionality is to add a Java exception breakpoint, which gets triggered when the said exception is thrown.

How to save YouTube videos on desktop?

Many a times we come across a video on YouTube which we want to save on desktop. You can watch the video again later without visiting the internet. Well this can be done easily in few steps.

Watch the full video which you want to save on youtube in Internet Explorer.

Goto Tools > Internet Options > Browsing History > Settings > View Files. A explorer window will open.

Click on "Last Accessed" column header such that the column gets sorted with latest time on top.

Look for "Flash video" under column "Type". That row is for the video you just watched.

Copy that file and paste on your desktop.

The file extension will be .flv

Play the file in your favorite player which supports flv.

I use VLC to play all types of videos including flv.

Stack Overflow

Few months ago, I came across a programming question and answer (Q & A) site named Stack Overflow. Joel Spolsky and Jeff Atwood are the founder of this wonderful site. Its a fairly new site, only 8 months into existence as of now. But the community is already huge and people are active round the clock, questions get answered in no time.

Well what is special about this site, there are thousands of forums and sites where one can ask programming related questions.

I liked Stack Oveflow because its super fast. You must have seen other Q & A sites, visit the site to feel the difference. The other aspect of the site which I like is its a one stop destination for any programming language. I am a Java developer but like to read questions and answers of other language as well. In my view it at least provides an overview of what the language is all about. The questions are tagged with proper labels like java, c#, ruby, etc., one can filter questions based on preferences.

Stack Overflow is built and maintained by the community itself. Good Q & A earn reputation points, bad one gets negative points. User gets various admin rights based on how many points earned. This concept produces good quality questions and answers. Unlike other forums anyone with rights can correct others post to maintain the correctness of the site, just like Wikipedia.

About me

I am Bhushan Bhangale. I live in Pune, India with my wife and a lovely daughter. I am a software developer mainly programming in Java (what the heck), well for my living.

I am not an expert of anything but thought writing will at least help me developing my writing skills, if not helping or amusing anybody with my thoughts. Also I will get to know your view on my thoughts if you managed to spot me in this vast jungle of beautiful blogs.

I will be writing my experience of various things I come across in my day to day life. Be it programming (well you see I know a bit of Java), reviews of products, general thoughts, etc. Of course the thoughts will be to the point as you expect from my blog title.

If you want to contact me then you can leave comments on my blogs. Other than that I am reachable on bbhangale@gmail.com.