For installing Latest Oracle Java:
To check ubuntu system architecture installed
$ uname -m
or
$ arch
Download the Oracle Java JDK for Linux. Make sure you select the correct compressed binaries for your system architecture 32-bit or 64-bit (which end in tar.gz).It will be downloaded in Downloads folder in home.So first open nautilus with sudo as
sudo nautilus
and make a folder java under
/usr/local/
and then folow the following commands:
cd /home/"your_user_name"/Downloads
sudo cp -r jdk-7u40-linux-x64.tar.gz /usr/local/java
cd /usr/local/java
sudo chmod a+x jdk-7u40-linux-x64.tar.gz
sudo tar xvzf jdk-7u40-linux-x64.tar.gz
At this point you should have two uncompressed binary directories in /usr/local/java check it by
ls -a
Now edit the system path file by
sudo gedit /etc/profile
scroll down to the last and add following lines
JAVA_HOME=/usr/local/java/jdk1.7.0_40
PATH=$PATH:$HOME/bin:$JAVA_HOME/bin
export JAVA_HOME
export PATH
Save and exit and write these commands in terminal to Inform your Ubuntu Linux system where your Oracle Java JDK/JRE is located.
sudo update-alternatives --install "/usr/bin/java" "java" "/usr/local/java/jdk1.7.0_40/bin/java" 1
sudo update-alternatives --install "/usr/bin/javac" "javac" "/usr/local/java/jdk1.7.0_40/bin/javac" 1
sudo update-alternatives --install "/usr/bin/javaws" "javaws" "/usr/local/java/jdk1.7.0_40/bin/javaws" 1
sudo update-alternatives --set java /usr/local/java/jdk1.7.0_40/bin/java
sudo update-alternatives --set javac /usr/local/java/jdk1.7.0_40/bin/javac
sudo update-alternatives --set javaws /usr/local/java/jdk1.7.0_40/bin/javaws
. /etc/profile
Now everything is installed just check it by
java -version
the output must be like
java version "1.7.0_40"
Java(TM) SE Runtime Environment (build 1.7.0_40-b40)
Java HotSpot(TM) Server VM (build 23.1-b03, mixed mode)
Congratulation now its installed.