Switching multiple JDK environments under Ubuntu
When you install Ubuntu, OpenJDK_1.7 is installed by default
$java-version
Java version "1.7.079"
OpenJDK Runtime Environment (IcedTea 2.5.6) (7u79-2.5.6-0ubuntu1.12.04.1)
OpenJDK 64-Bit Server VM (build 24.79-b02, mixed mode)
Now you need to install JDK_1.6
Installed in / opt/java/jdk1.6.0_45
/ opt/java/jdk1.6.0_45# ls
Bin db jre LICENSE README.html THIRDPARTYLICENSEREADME.txt
COPYRIGHT include lib man src.zip
Plus environmental variables
User environment variable: ~ / .add lines to bashrc
Export JAVA_HOME=/opt/java/jdk1.6.0_45
Export JRE_HOME=$JAVA_HOME/jre
Export CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JRE_HOME/lib/tools.jar
Export PATH=$PATH:$JAVA_HOME/bin:$JRE_HOME/bin
Export USE_CCACHE=1
System environment variable: add lines to / etc/profile
Export JAVA_HOME=/opt/java/jdk1.6.0_45
Export JRE_HOME=$JAVA_HOME/jre
Export CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JRE_HOME/lib/tools.jar
Export PATH=$PATH:$JAVA_HOME/bin:$JRE_HOME/bin
Export USE_CCACHE=1
Switch software versions through update-alternatives
Add command connectors for JDK_1.6, using the-- install option
$sudo update-alternatives-- install / usr/bin/java java/ opt/java/jdk1.6.0_45/bin/java 1062
To remove,-- remove option
$sudo update-alternatives-- remove / usr/bin/java java/ opt/java/jdk1.6.0_45/bin/java 1062
Create a default command link-- config
$sudo update-alternatives-config java
There are 2 choices for the alternative java (providing / usr/bin/java).
Selection Path Priority Status
* 0 / opt/java/jdk1.6.0_45/bin/java 1062 auto mode
1 / opt/java/jdk1.6.0_45/bin/java 1062 manual mode
2 / usr/lib/jvm/java-7-openjdk-amd64/jre/bin/java 1051 manual mode
Press enter to keep the current choice [*], or type selection number:0
In the same way, Python can switch in this way.
2017-6-16 New
A more detailed English quote mark is as follows:
Use Oracle Java JDK, by following the steps below:
Visit http://www.oracle.com/technetwork/java/javase/downloads/java-archive-downloads-javase6-419409.html
Accept the license agreement
Download jdk-6uXX-linux-x64.bin (where XX is the latest minor version)
If you don't have an Oracle account and don't want to create one, you can have a look at http://bugmenot.com/view/oracle.com
Here is how to configure Oracle Java JDK to be the default on Ubuntu:
Cd / usr/lib/jvm & & sudo / bin/sh ~ / Downloads/jdk-6u38-linux-x64.bin-noregister
Note: You might get / bin/sh: jdk-6u43-linux-x64.bin: Permission denied error. This happens because root does not permissions to read the / Downloads folder.
Option 1: Temporarily change the permissions of ~ / Downloads folder for root to have read permission.
Chmod 755 ~ / Downloads/
Don't forget to change it back once you are done!
Option 2: Copy the downloaded file to / usr/lib/jvm and do
Sudo / bin/sh jdk-6u38-linux-x64.bin-noregister
In either case, then set it as default.
Sudo update-alternatives-install / usr/bin/javac javac / usr/lib/jvm/jdk1.6.0_38/bin/javac 50000sudo update-alternatives-install / usr/bin/java java / usr/lib/jvm/jdk1.6.0_38/bin/java 50000sudo update-alternatives-install / usr/bin/javaws javaws / usr/lib/jvm/jdk1.6.0_38/bin/javaws 50000sudo update-alternatives-install / usr/bin/javap javap / usr/lib/jvm/jdk1.6 0_38/bin/javap 50000sudo update-alternatives-- install / usr/bin/jar jar / usr/lib/jvm/jdk1.6.0_38/bin/jar 50000sudo update-alternatives-- install / usr/bin/jarsigner jarsigner / usr/lib/jvm/jdk1.6.0_38/bin/jarsigner 50000sudo update-alternatives-- config javacsudo update-alternatives-- config javasudo update-alternatives-- config javawssudo update-alternatives-- config javapsudo update-alternatives-- config jarsudo update-alternatives-- config jarsigner
Also make sure / usr/bin/java is first in your $PATH. I.e.
Which java
Should return / usr/bin/java.
