How to set JAVA_HOME in Linux for all users

I am new to Linux system and there seem to be too many Java folders.

java -version gives me:

• java version "1.7.0_55"
• OpenJDK Runtime Environment (rhel-2.4.7.1.el6_5-x86_64 u55-b13)
• OpenJDK 64-Bit Server VM (build 24.51-b03, mixed mode)

When I am trying to build a Maven project , I am getting error:

Error: JAVA_HOME is not defined correctly.
We cannot execute /usr/java/jdk1.7.0_05/bin/java

Could you please tell me which files I need to modify for root as well as not-root user and where exactly is java located?

1. find /usr/lib/jvm/java-1.x.x-openjdk

2. vim /etc/profile

   Prepend sudo if logged in as not-privileged user, ie. sudo vim

3. Press 'i' to get in insert mode

4. add:

   export JAVA_HOME="path that you found"
   
   export PATH=$JAVA_HOME/bin:$PATH
   

5. logout and login again, reboot, or use source /etc/profile to apply changes immediately in your current shell