Install JAVA on CentOS or RHEL 5/6

Step by Step Installation JAVA on CentOS or RHEL 5&6

     Use these steps to Install JAVA on Redhat or CentOS 5&6


Step 1: 
   
    Download latest version of java
    
    from  http://www.oracle.com/technetwork/java/javase/downloads/jdk7-downloads-1880260.html
   If you are using terminal  (Command Mode)
 
  [root@localhost ~]# cd /opt/
 
  [root@localhost opt]# wget http://download.oracle.com/otn-pub/java/jdk/7u45-b18/jdk-7u45-linux-x64.tar.gz?AuthParam=1386151125_6d26b53924dbf30cd114f1ec8d20d78c
  
  Extract downloaded archive using following command.

   [root@localhost opt]# tar -xvzf  jdk-7u25-linux-  i586.tar.gz?AuthParam=1377944382_824ed437096a64593579b2d07b8e242e
    
   [root@localhost opt]#  ls -l
   
     drwxr-xr-x  8 uucp  143 4096 Jun  6 09:53 jdk1.7.0_25


Step 2:

     Install JAVA using Alternatives

     After extracting java archive file, we just need to setup to use newer version of java using alternatives. Use the following commands to do it.  


   [root@localhost opt]# cd /opt/jdk1.7.0_25/
  
   [root@localhost opt]# alternatives --install /usr/bin/java java /opt/jdk1.7.0_25/bin/java 2
  
   [root@localhost opt]#alternatives --config java


         There are 3 programs which provide 'java'.


         Selection    Command
     -----------------------------------------------
             1           /usr/lib/jvm/jre-1.7.0-openjdk.x86_64/bin/java
             2           /usr/lib/jvm/jre-1.6.0-openjdk.x86_64/bin/java
             3           /opt/jdk1.7.0_25//bin/java

      Enter to keep the current selection[+], or type selection number:   3


  Now you have successfully configured java in your system. Go to next step to check current installed version.


Step 3:
 
    Check Version of JAVA .
 
    [root@localhost ~]# java  -version

       java version "1.7.0_25"
       Java(TM) SE Runtime Environment (build 1.7.0_25-b15)
       Java HotSpot(TM) Client VM (build 23.25-b01, mixed mode)


Step 4: 

        Setup Environment Variables


    Most of java based application’s uses environment variables to work. Use following commands to setup it.
 

•   Setup JAVA_HOME Variable

                   [root@localhost opt]# export JAVA_HOME=/opt/jdk1.7.0_25

•   Setup JRE_HOME Variable

                   [root@localhost opt]# export JRE_HOME=/opt/jdk1.7.0_25/jre

•   Setup PATH Variable

               [root@localhost opt]# export PATH=$PATH:/opt/jdk1.7.0_25/bin:/opt/jdk1.7.0_25/jre/bin


 You can follow above steps to install multiple version of java as same time,  but you can use only one version at a time.