How to install the JDK on Ubuntu Linux

Note: This is an old question and the answers reflect the world as it was then. Modern Ubuntu distributions have OpenJDK available which can be installed with

sudo apt install default-jdk

I am trying to install the Java Development Kit (JDK) on Ubuntu Linux distribution, but I am unable to install it.

What are the steps to install it on Ubuntu?

Referring to Ask Ubuntu question How to set JAVA_HOME for OpenJDK?,

How to install Open JDK (Java developement kit) in Ubuntu (Linux)?

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Open Terminal from Application Dash or press Ctrl+Alt+T

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Update repository:

sudo add-apt-repository ppa:openjdk-r/ppa  # only Ubuntu 17.4 and earlier
sudo apt update

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Optional: To search available distributions of openjdk, use the following command:

apt search openjdk

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Install the appropriate version with the following command:

sudo apt install openjdk-8-jdk
sudo apt install openjdk-8-source #this is optional, the jdk source code

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For JAVA_HOME (Environment Variable) type command as shown below, in "Terminal" using your installation path...

export JAVA_HOME=/usr/lib/jvm/java-8-openjdk

(Note: /usr/lib/jvm/java-8-openjdk is symbolically used here just for demostration. You should use your path as per your installation.)

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For PATH (Environment Variable) type command as shown below, in Terminal:

export PATH=$PATH:$JAVA_HOME/bin

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To check your installation:

java -version

Stack Overflow Q#14788345, score: 858