Ubuntu Install Java JDK and JRE

Ubuntu Linux Install Sun Java Development Kit ( JDK ) and Java Runtime Environment ( JRE )
by Vivek Gite
 
Q.
How do I install Sun
Java Development Kit (JDK) and Java Runtime Environment (JRE) under
Ubuntu Linux? It appears that there are multiple JRE installed by
default under Ubuntu. How do I select and use Sun JRE only? Can you
explain steps required to set the environment to run java programs or
apps?
A.
Ubuntu Linux 7.10 has following packages from Sun:
=> sun-java6-bin
: Sun Java Runtime Environment (JRE) 6
=> sun-java6-demo
: Sun Java Development Kit (JDK) 6 demos
=> sun-java6-jdk
: Sun Java Development Kit (JDK) 6
=> sun-java6-jre
: Sun Java Runtime Environment (JRE) 6
Install Sun Java 6
Open a shell prompt (terminal) and type the following to install JDK and JRE:
$ sudo apt-get install sun-java6-bin sun-java6-jre sun-java6-jdk
Setup the default Java version
Ubuntu Linux comes with update-java-alternatives utility to updates
all alternatives belonging to one runtime or development kit for the
Java language. To select, Sun's JVM as provided in Ubuntu 7.10, enter:
$ sudo update-java-alternatives -s java-6-sun
You also need to edit a file called /etc/jvm. This file defines the
default system JVM search order. Each JVM should list their JAVA_HOME
compatible directory in this file. The default system JVM is the first
one available from top to bottom. Open /etc/jvm
$ sudo vi /etc/jvm
Make sure /usr/lib/jvm/java-6-sun is added to the top of JVM list
/usr/lib/jvm/java-6-sun
At the end your file should read as follows:
/usr/lib/jvm/java-6-sun
/usr/lib/jvm/java-gcj
/usr/lib/jvm/ia32-java-1.5.0-sun
/usr/lib/jvm/java-1.5.0-sun
/usr
Save and close the file.
Setup the environment variable
You also need to setup JAVA_HOME and PATH variable. Open your
$HOME/.bash_profile or /etc/profile (system wide) configuration. Open
your .bash_profile file:
$ vi
$HOME/.bashrc
Append following line:
#set java envir