INSTALLATION OF ORACLE JAVA 7 ON UBUNTU 12.04

This post will be useful to install oracle java 7 on ubuntu .

If you have the OpenJDK/JRE installed on your system, you can remove it by typing the following at the command line:

Type/Copy/Paste: sudo apt-get purge openjdk-\*  

This command will completely remove OpenJDK/JRE from your system .

 Create java folder in usr/lib/jvm , you can create it by following command line :

Type/Copy/Paste: sudo mkdir -p /usr/lib/jvm/java

This command will create a directory to hold your Oracle Java JDK and JRE binaries.

 Download jdk and jre from here

Extract that files and copy and paste it into usr/lib/jvm/java folder 


Edit the system PATH file /etc/profile and add the following system variables to your system path

Type/Copy/Paste: sudo gedit /etc/profile

Scroll down to the end of the file using your arrow keys and add the following lines below to the end of your /etc/profile file:  

Type/Copy/Paste:

JAVA_HOME=/usr/lib/jre/java/jdk1.7.0_21
PATH=$PATH:$HOME/bin:$JAVA_HOME/bin
JRE_HOME=/usr/lib/jre/java/jre1.7.0_21
PATH=$PATH:$HOME/bin:$JRE_HOME/bin
export JAVA_HOME
export JRE_HOME
export PATH

Save the /etc/profile file and exit.

Inform your Ubuntu Linux system where your Oracle Java JDK/JRE is located. This will tell the system that the new Oracle Java version is available for use. 

Type/Copy/Paste: sudo update-alternatives --install "/usr/bin/java" "java" "/usr/lib/jre/java/jre1.7.0_21/bin/java" 1 

this command notifies the system that Oracle Java JRE is available for use .

Type/Copy/Paste: sudo update-alternatives --install "/usr/bin/javac" "javac" "/usr/lib/jre/java/jdk1.7.0_21/bin/javac" 1 

this command notifies the system that Oracle Java JDK is available for use

Type/Copy/Paste: sudo update-alternatives --install "/usr/bin/javaws" "javaws" "/usr/lib/jre/java/jre1.7.0_21/bin/javaws" 1 

this command notifies the system that Oracle Java Web start is available for use

Inform your Ubuntu Linux system that Oracle Java JDK/JRE must be the default Java.

Type/Copy/Paste: sudo update-alternatives --set java /usr/lib/jre/java/jre1.7.0_21/bin/java  
this command will set the java runtime environment for the system

Type/Copy/Paste: sudo update-alternatives --set javac /usr/lib/jre/java/jdk1.7.0_21/bin/javac

this command will set the javac compiler for the system

Type/Copy/Paste: sudo update-alternatives --set javaws /usr/lib/jre/java/jre1.7.0_21/bin/javaws

this command will set Java Web start for the system

Reload your system wide PATH /etc/profile by typing the following command: 

Type/Copy/Paste: . /etc/profile

Note your system-wide PATH /etc/profile file will reload after reboot of your Ubuntu Linux system

Test to see if Oracle Java was installed correctly on your system. Run the following commands and note the version of Java:

Type/Copy/Paste: java -version 
 this should display

java version "1.7.0_21"
Java(TM) SE Runtime Environment (build 1.7.0_21-b21)
Java HotSpot(TM) Server VM (build 23.1-b03, mixed mode)

Type/Copy/Paste: javac -version  

javac 1.7.0_21

That's all you just installed Oracle Java on your Linux system .

Note : Check your JAVA_PATH and JRE_PATH in terminal by following commands :

Type/Copy/Paste: echo $JAVA_HOME

it will display   /usr/lib/jvm/java/jdk1.7.0_21


Type/Copy/Paste: echo $JRE_HOME

it will display  /usr/lib/jvm/java/jre1.7.0_21


If terminal show this paths then all is set . Sometimes you may not get this paths correctly that time you should follow this steps

Goto your home folder and press CTRL + F , you can get .bashrc file  in that file you can export your java path add following line at end of the file or modify JAVA_HOME

 export JAVA_HOME=/usr/lib/jvm/java/jdk1.7.0_21


That's all everything done ....