How to set JAVA_HOME path on Ubuntu?

How can I setup JAVA_HOME path without having to set it each time I restart my machine?

I've used the following ways when trying to set JAVA_HOME on my Ubuntu machine:

1. From terminal I've executed the following command:

   export JAVA_HOME=/usr/lib/jvm/jdk1.7.0

2. I've edited the /etc/enviroment file directly to add JAVA_HOME path in it

What's really strange is that if I test JAVA_HOME using the echo command after an of the above two ways, I can see it is set correctly, but if I restart, logout/ login again or even after working on the machine for a while the JAVA_HOME is no more set and I have to set it again using any of the above two ways.

So can someone please tell me what I am doing wrong here?

add JAVA_HOME to the file:

/etc/environment

for it to be available to the entire system (you would need to restart Ubuntu though)

I normally set paths in

~/.bashrc

However for Java, I followed instructions at https://askubuntu.com/questions/55848/how-do-i-install-oracle-java-jdk-7

and it was sufficient for me.

you can also define multiple java_home's and have only one of them active (rest commented).

suppose in your bashrc file, you have

export JAVA_HOME=......jdk1.7

#export JAVA_HOME=......jdk1.8

notice 1.8 is commented. Once you do

source ~/.bashrc

jdk1.7 will be in path.

you can switch them fairly easily this way. There are other more permanent solutions too. The link I posted has that info.