how to do java installation in Linux(Ubuntu)

Question 1

In the link you have provided above there is not mention about version of java. Also, the installation steps are direct.

Anyway to just specify an exact version of a package using apt-get you could do(apache2 installation example)

sudo apt-get install apache2=2.2.20-1ubuntu1

go through this link

Question 2

Step 1: Check to see if your Ubuntu Linux operating system architecture is 32-bit or 64-bit, open up a terminal and run the following command below.

file /sbin/init

Note: the bit version of your Ubuntu Linux operating system architecture it will display whether it is 32-bit or 64-bit.

Step 2: Check if you have Java installed on your system. To do this, you will have to run the Java version command from terminal.

Open up a terminal and enter the following command:

java -version

If you have OpenJDK installed on your system it may look like this:

java version "1.7.0_15"
OpenJDK Runtime Environment (IcedTea6 1.10pre) (7b15~pre1-0lucid1)
OpenJDK 64-Bit Server VM (build 19.0-b09, mixed mode)

If you have OpenJDK installed on your system, you have the wrong vendor version of Java installed for this exercise.

Step 3: Completely remove the OpenJDK/JRE from your system and create a directory to hold your Oracle Java JDK/JRE binaries. This will prevent system conflicts and confusion between different vendor versions of Java. For example, if you have the OpenJDK/JRE installed on your system, you can remove it by typing the following at the command line:

sudo apt-get purge openjdk-\*

This command will completely remove OpenJDK/JRE from your system

sudo mkdir -p /usr/local/java

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

Step 4: Download the Oracle Java JDK/JRE for Linux.Make sure you select the correct compressed binaries for your system architecture 32-bit or 64-bit (which end in tar.gz).

For example, if you are on Ubuntu Linux 32-bit operating system download 32-bit Oracle Java binaries.
For example, if you are on Ubuntu Linux 64-bit operating system download 64-bit Oracle Java binaries.
Important Information: 64-bit Oracle Java binaries do not work on 32-bit Ubuntu Linux operating systems, you will receive multiple system error messages, if you attempt to install 64-bit Oracle Java on 32-bit Ubuntu Linux.

Step 5: Copy the Oracle Java binaries into the /usr/local/java directory. In most cases, the Oracle Java binaries are downloaded to:

/home/"your_user_name"/Downloads

32-bit Oracle Java on 32-bit Ubuntu Linux installation instructions:

cd /home/"your_user_name"/Downloads

sudo cp -r jdk-7u45-linux-i586.tar.gz /usr/local/java

sudo cp -r jre-7u45-linux-i586.tar.gz /usr/local/java

cd /usr/local/java

64-bit Oracle Java on 64-bit Ubuntu Linux installation instructions:

cd /home/"your_user_name"/Downloads

sudo cp -r jdk-7u45-linux-x64.tar.gz /usr/local/java

sudo cp -r jre-7u45-linux-x64.tar.gz /usr/local/java

cd /usr/local/java

Step 6: Unpack the compressed Java binaries, in the directory /usr/local/java

32-bit Oracle Java on 32-bit Ubuntu Linux installation instructions:

sudo tar xvzf jdk-7u45-linux-i586.tar.gz
sudo tar xvzf jre-7u45-linux-i586.tar.gz

64-bit Oracle Java on 64-bit Ubuntu Linux installation instructions:

sudo tar xvzf jdk-7u45-linux-x64.tar.gz
sudo tar xvzf jre-7u45-linux-x64.tar.gz

Step 7: Double-check your directories. At this point, you should have two uncompressed binary directories in /usr/local/java for the Java JDK/JRE listed as:

ls -a

Output should be

jdk1.7.0_45
jre1.7.0_45

Step 8: Edit the system PATH file /etc/profile and add the following system variables to your system path. Use nano, gedit or any other text editor, as root, open up /etc/profile.

sudo gedit /etc/profile
(or)
sudo nano /etc/profile

Step 9: 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:

JAVA_HOME=/usr/local/java/jdk1.7.0_45
PATH=$PATH:$HOME/bin:$JAVA_HOME/bin
JRE_HOME=/usr/local/java/jre1.7.0_45
PATH=$PATH:$HOME/bin:$JRE_HOME/bin
export JAVA_HOME
export JRE_HOME
export PATH

Save the file

Step 10: 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.

sudo update-alternatives --install "/usr/bin/java" "java" "/usr/local/java/jre1.7.0_45/bin/java" 1

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

sudo update-alternatives --install "/usr/bin/javac" "javac" "/usr/local/java/jdk1.7.0_45/bin/javac" 1

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

sudo update-alternatives --install "/usr/bin/javaws" "javaws" "/usr/local/java/jre1.7.0_45/bin/javaws" 1

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

Step 11: Inform your Ubuntu Linux system that Oracle Java JDK/JRE must be the default Java.

sudo update-alternatives --set java /usr/local/java/jre1.7.0_45/bin/java

this command will set the java runtime environment for the system

sudo update-alternatives --set javac /usr/local/java/jdk1.7.0_45/bin/javac

this command will set the javac compiler for the system

sudo update-alternatives --set javaws /usr/local/java/jre1.7.0_45/bin/javaws

this command will set Java Web start for the system

Step 12: Reload your system wide PATH /etc/profile by typing the following command:

./etc/profile

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

Step 13: A successful installation of Oracle Java will display:

for 32-bit

java -version
java version "1.7.0_45"
Java(TM) SE Runtime Environment (build 1.7.0_45-b18)
Java HotSpot(TM) Server VM (build 24.45-b08, mixed mode)

javac -version
javac 1.7.0_45

for 64-bit

java -version
java version "1.7.0_45"
Java(TM) SE Runtime Environment (build 1.7.0_45-b18)
Java HotSpot(TM) 64-Bit Server VM (build 24.45-b08, mixed mode)

javac -version
javac 1.7.0_45

Congratulations, you just installed Oracle Java on your Linux system. Now reboot your Ubuntu Linux system. Afterwards, your system will be fully configured for running and developing Java programs

Question 3

I always use the Oracle JDK Download site. This allows you to get any version of Java 6 you want, or any version back to Java 1.1.

BTW I would consider upgrading from ubuntu 10.04 to 12.04 if not 13.10.