Install JAVA manually in UBUNTU

Installing Oracle JDK

First download the tar file of java version u required. Follow I downloaded 1.7

You will need sudo privileges to perform this task:

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        sudo su

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The /opt directory is reserved for all the software and add-on packages that are not part of the default installation. Create a directory for your JDK installation:  

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          mkdir /opt/jdk

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and extract java into the /opt/jdk directory:  

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        tar -zxf jdk-7u67-linux-x64.tar.gz -C /opt/jdk

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Verify that the file has been extracted into the /opt/jdk directory.
 

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        ls /opt/jdk

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Setting Oracle JDK as the default JVM

In our case, the java executable is located under /opt/jdk/jdk1.7.0_67/bin/java . To set it as the default JVM in your machine run:  

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        update-alternatives --install /usr/bin/java java /opt/jdk/jdk1.7.0_67/bin/java 100

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and  

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        update-alternatives --install /usr/bin/javac javac /opt/jdk/jdk1.7.0_67/bin/javac 100

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Verify your installation


Verify that java has been successfully configured by running:

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        update-alternatives --display java

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and

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        update-alternatives --display javac

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