Setting Java Environment PATH

Check if JDK/JRE is installed

Open Command Line Terminal (On Windows: [Start > Accessories > Command Prompt]) and type the following command:

java -version

Remember to leave a space between java and a dash. If the command displays the version of Java, you are good to go without Java installation. Otherwise, download it from http://www.oracle.com/technetwork/java/javase/downloads/index.html.

Install JDK/JRE

On Windows

Run the Java Installer and follow the instructions.

On Linux

Visit the following page to get the complete step-by-step explanation how to get JDK or JRE installed on Linux
http://www.oracle.com/technetwork/java/javase/install-linux-self-extracting-138783.html

Set Java Environment PATH

On Windows

Check if JAVA_HOME environment variable is set at [My Computer > System Properties > Advanced Tab > Environment Variables > System Variables Block]. If you do not see JAVA_HOME variable listed:

Click on the New button to add a new variable. Enter JAVA_HOME as a Variable name and the Java installation PATH as a Variable value. Press OK button to save.

In the same window find the existing PATH variable and edit it by adding the %JAVA_HOME%/bin; string at the end of the current value. Press OK button to save.

On Linux

1. Navigate to your home directory.
2. If you cannot see .bashrc file, it is hidden. Press Ctrl+H if you are in the Desktop environment.
3. Open .bashrc file in the editor.
4. Add the following lines at the end of the file.
   

   export JAVA_HOME=/home/user/bin/jdk1.5.0_09
   export PATH=$JAVA_HOME/bin:$PATH
   

   Do not forget to change the first line of the code to the actual PATH where you have installed your JAVA package.