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.    

   

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   1. uname -a or file /sbin/init

 Linux caochu-Inspiron-N5110 3.13.0-32-generic #57-Ubuntu SMP Tue Jul 15 03:51:08 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux

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

1. Type/Copy/Paste:java -versio

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

2. sudo apt-get purge openjdk-*

Download the Oracle Java JDK for Linux.

1. Unpack the compressed Java binaries, in the directory /usr/local/java8

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:

1.  export JAVA_HOME=/usr/local/java8/jdk1.8.0_73 
    export JRE_HOME=${JAVA_HOME}/jre  
    export CLASSPATH=.:${JAVA_HOME}/lib:${JRE_HOME}/lib  
    export PATH=${JAVA_HOME}/bin:$PATH

2.  source /etc/profile

 Configure default JDK version :

1.   sudo update-alternatives --install /usr/bin/java  java  /usr/local/java8/jdk1.8.0_73/bin/java      300
    sudo update-alternatives --install /usr/bin/javac javac /usr/local/java8/jdk1.8.0_73/bin/javac    300
    sudo update-alternatives --install /usr/bin/jar   jar   /usr/local/java8/jdk1.8.0_73/bin/jar 300
    sudo update-alternatives --install /usr/bin/javah javah /usr/local/java8/jdk1.8.0_73/bin/javah  300
     sudo update-alternatives --install /usr/bin/javap javap /usr/local/java8/jdk1.8.0_73/bin/javap 300

2. sudo update-alternatives --config java 

Test

1. java -version

文章标题：ubuntu——HowtoInstallOracleJavaJDK8
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