Java – rubymine on Linux

I'm new in Ubuntu and have a problem I can't start rubymine 4:

kvet@Kvet-Notebook:~/Rubymine-4.0.3/bin$java -version
java version "1.7.0_03"
OpenJDK Runtime Environment (IcedTea7 2.1.1pre) (7~u3-2.1.1~pre1-1ubuntu2)
OpenJDK 64-Bit Server VM (build 22.0-b10,mixed mode)
kvet@Kvet-Notebook:~/Rubymine-4.0.3/bin$./rubymine.sh
OpenJDK Runtime Environment (IcedTea7 2.1.1pre) (7~u3-2.1.1~pre1-1ubuntu2)
OpenJDK 64-Bit Server VM (build 22.0-b10,mixed mode)
OpenJDK 64-Bit Server VM (build 22.0-b10,mixed mode)
WARNING: You are launching the IDE using OpenJDK Java runtime.

         THIS IS STRICTLY UNSUPPORTED DUE TO KNowN PERFORMANCE AND GRAPHICS PROBLEMS!

NOTE:    If you have both Oracle (Sun) JDK and OpenJDK installed
         please validate either RUBYmine_JDK,JDK_HOME,or JAVA_HOME environment variable points to valid Oracle (Sun) JDK installation.
         See http://ow.ly/6TuKQ for more info on switching default JDK.

Press Enter to continue.

Error: Could not find or load main class com.intellij.idea.Main

I tried to install openjdk6 with the same error I don't know what I should do

Solution

I recently had this ([error: cannot start rubymine. No JDK found. JDK version? + desktop link])

Download Oracle7 JDK at: http://www.oracle.com/technetwork/java/javase/downloads/java-se-jdk-7-download-432154.html

Follow the instructions below: http://www.webupd8.org/2011/09/how-to-install-oracle-java-7-jdk-in.html for example

After downloading Java (Part 1): unzip the downloaded Oracle Java JDK archive to the main folder, and rename the newly created folder "java-7-oracle"

sudo mv its_name java-7-oracle

Install it:

cd
sudo mkdir -p  /usr/lib/jvm/ #just in case
sudo mv java-7-oracle/ /usr/lib/jvm/
sudo add-apt-repository ppa:nilarimogard/webupd8
sudo apt-get update
sudo apt-get install update-java
sudo update-java

Verification:

java -version
javac -version