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How do I make java default to a manually installed JRE/JDK?

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linux-howto

http://askubuntu.com – I have Ubuntu 12.04 amd64 installed on my machine, on the previous versions of Ubuntu it was deadly easy, now there is this command update-java-alternatives with a really bad man page. I just have my JDK unpacked on a mounted partition like /media/mydisk/jdk, how i can force the use of that JDK instead of the one that comes in the Ubuntu repository? What is the logic behind this update-java-alternatives ? (HowTos)

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Submitted by funckax on 07/04/2012 – Made popular on 07/04/2012

Stories similar to How do I make java default to a manually installed JRE/JDK?

I've got java-6-openjdk and java-7-openjdk running on Natty (11.04) on one machine and successfully toggle between them using update-alternatives --config java (or javac).

For some reason this doesn't seem to work on a second machine of identical spec.

Hello, the default java installation is openJDK.

/usr/bin/java -> /etc/alternatives/java /etc/alternatives/java -> /usr/lib/jvm/jre-1.7.0-openjdk.x86_64/bin/java

I want to install JDK 1.6, and executed this command:

Code: alternatives --install /usr/bin/java java /usr/lib/java/jdk1.6.0_45/bin/java 20000 But the symbolic link does change at all. What might be wrong?

What is the command update-alternatives used for?

Take this example:

sudo update-alternatives --install /usr/bin/java java /usr/local/java/jre1.7.0_09/bin/java 1

What does it do? How is it different from adding jdk to the path?

Let's say that I have run the command. How would I revert back to the original state?

Code: root@opus:~# sudo update-alternatives --install "/usr/share/java" "java" "/usr/share/java/jdk1.7.0/bin/java" 1 update-alternatives: warning: forcing reinstallation of alternative /usr/share/java/jdk1.7.0/bin/java because link group java is broken. update-alternatives: warning: not replacing /usr/share/java with a link. Please help

I want to have two JDKs. The first one was installed a long time ago to /usr/lib/jvm/java-7-oracle/.

when I load the application, I get Code: /usr/lib/jvm/java-7-ibm/jre/bin/java/bin/java not found ????

How come it is not working?

I followed the instructions here http://www.wikihow.com/Install-IBM-Java-on-Ubuntu-Linux

however I only loaded sdk since it has jre.

Sorry for my bad English, but I'm really trying to be better. Ok. I've created a new command/alias(changejava) on Ubuntu 12.04, and I need to skip "sudo password" only when I write "$changejava". If I write "$changejava" using terminal, Ubuntu show me what can I do. I just need to press 0, 1 or 2.

Compiling is easy but when using java to run the programs, it gives Exception found. I am using Ubuntu 12.04 without internet connections. Also, installed Oracle JDK7 and JRE7. Also did the update-alternatives command on java, javac and javaws. Changed the machine java in /etc/profiles. PATH is pointing to oracle java folder.

Recently I installed jdk 1.7 in ubuntu. These are the steps that I used to install it.

1. Extracted the folder named 'jdk1.7.0' and copied it to '/usr/lib/jvm'.

2. Installed javac using the following command sudo update-alternatives --install /usr/bin/javac javac /usr/lib/jvm/jdk1.7.0/bin/javac 4

3.