[java] 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)