the program javac can be found in the following packages ubuntu

Question

typing

$ java -version
The program 'java' can be found in the following packages:
  * gcj-4.4-jre-headless
  * gcj-4.5-jre-headless
  * openjdk-6-jre-headless
Try: sudo apt-get install <selected package>

I've installed oracle jdk-7u15-linux-i586.tar.gz by following http://www.wikihow.com/Install-Oracle-Java-on-Ubuntu-Linux. Also,

$ javac
The program 'javac' can be found in the following packages:
  * openjdk-6-jdk
  * ecj
  * gcj-4.4-jdk
  * gcj-4.5-jdk
Try: sudo apt-get install <selected package>

Please help me to have only Sun JDK/JRE on the system. I run Ubuntu 11.04, using wubi.