Tech Trek: A Software Engineer's Guide to Code and Beyond

What are Java Annotations? Annotations is a new feature from Java 5. Annotations are a kind of comment or meta data you can insert in your Java code. These annotations can then be processed at compile time by pre-compiler tools, or at runtime via Java Reflection. The annotation can be attached to Classes, Methods,Parameters,Fields etc. How to create custom Annotation? To create an annotation we use the interface keyword and add an @ symbol infront of it. The @ symbol will tell the compiler that it doing some business with an annotation. @Retention (RetentionPolicy.RUNTIME) public @interface MyAnnotation { String value(); } The @ in front of the interface marks it as an annotation. Once you have defined the annotation you can use it in your code.Here is an example of class annotation: @MyAnnotation(value="Class Annotation") public class MyClass { } The two directives in the annotation definition, @Retention(RetentionPolicy.RUNTIME) and @Target(El...

When we trying to install the flash player for your linux operating system, we download file libflashplayer.so but we do know where to put this file. This article guild you step by step to install the flash player for linux. Step 1: Go to Adobe website and download you suitable version of flash player libflashplayer.so 32-bit/64bit . Then extract it to libflashplayer.so File. Step 2: cd to the folder has file libflashplayer.so and install If you are using FireFox: sudo mv libflashplayer.so /usr/lib/mozilla/plugins/libflashplayer.so   If you are using Google Chrome + Firefox sudo mv libflashplayer.so /usr/lib/mozilla/plugins/libflashplayer.so sudo mkdir /opt/google/chrome/plugins sudo cp /usr/lib/flashplugin-installer/libflashplayer.so  /opt/google/chrome/plugins Thanks.

*) How to extract tr.gz. file To extract one or more members from an archive :               tar -zxvf {file.tar.gz} For example, If your tar name is backup.tar.gz, enter the following at a shell prompt:               tar -zxvf backup.tar.gz *) How to run .bin file Change the permission of the file you downloaded to be executable. Type the following command:               $ chmod +x file.bin Start the installation process or run .bin file.Type the following command:               ./file.bin For example if .bin file name is application.bin. Type:         $ chmod +x application.bin         $ ./application.bin *) How to set a BASH variable equal to the output from a command? Use $(), which I find easier to read, and allows for nesting.         OUTPUT=$(ls -1) echo $OUTPUT *) How to read IP ...

After installing Java Development Kit on Linux/Unix, you may still need to do some configuration to get Java ready for running or compiling Java programs. The following instruction will guide you through the process of setting up JDK for software development. In Linux, ~/.bash_profile is a startup script which generally runs once. This particular file is used for commands which run when the normal user logs in. Common uses for .bash_profile are to set environment variables such as PATH, JAVA_HOME, to create aliases for shell commands, and to set the default permissions for newly created files. Set JAVA_HOME / PATH for single user Login to your account and open .bash_profile file $ cd $HOME $ vi ~/.bash_profile Set PATH and JAVA_HOME as follows:   PATH=$PATH:$HOME/bin:/usr/jdk1.6.0_30/bin JAVA_HOME=/usr/jdk1.6.0_30 Note: Don't delete the previous PATH, Just append the jdk path after : like "/usr/jdk1.6.0_30/bin" as above . export PATH export JAVA_...

This tutorial shows how to enable SSL support for Apache Tomcat web server. Requirement *) Apache Tomcat 5.0 *) JDK 1.5 Note: if you have JDK below 1.4, you need to install Java Secure Socket Extensions (JSSE) To install and configure SSL support on Tomcat, you need to follow these simple steps. Generating the KeyStore file: *) Create a keystore file to store the server's private key and self-signed certificate by executing the following         command. *) Enter command line and change directory to your JAVA\bin folder. (Default path is: C:\Program         Files\Java\jre6\bin). *) Type “keytool –genkey –alias tomcat –keyalg RSA" and press Enter.         Where tomcat is an alias name and RSA is a key algorithm. *) Type your password for the keystore. (Default password is: changeit). In this example, I’ll use password as “password" Enter general information about this Certificate. The example is the image be...

The Calendar class’ date/time API is a nifty tool for accurately manipulating date and time values without too much stress or custom coding. It provides direct support for time based objects. This article gives a few examples how this API can be used. . The class java.util.Date was the first implementation which was used for manipulating dates. The class java.util.Calendar was added in Java 1.1 and provides simplified access to storing and manipulating dates. It is recommended to use Calendar if possible. In reality you have to convert frequently from Date to Calendar and vice versa, e.g. during database access you often get a java.sql.Date object. The following explains how to use Calendar and how to convert Dates into Calendar. It also offers a set of methods for converting and manipulating temporal information. In addition to retrieving the current date and time, the Calendar class also provides an API for date arithmetic. The API takes care of the numerous minor adjustments t...

I’ve been working with OSGi for quite awhile and have faced a problem "Workbench has not been createt yet" issues. I was getting this error, When i was trying to run OSGI plugin from Eclipse and I guess many of you must have face this problem. So i am writing a little bit about how to resolve this issue so others don’t repeat the same mistakes. From a good article on eclipsezone: java.lang.IllegalStateException: Workbench has not been created yet This usually comes when someone tries to run a Java application against an OSGi bundle with java -classpath .... . It really means that the workbench plug-in hasn't started yet, and so calls to getWorkbench() fail. This is essentially a race condition, and can be solved by either expressing an explicit dependency on that bundle or bumping up that bundle to a higher start level than the workbench. Generally not seen, but if it is, that's what's happening. Now to set the bundle to a higher start level than the work...