how to confirm java_home

1.install java 1.6 jdk
#apt-get install openjdk-6-jdk

2.use whereis to find javac
#whereis javac

3.use ls -al to confirm if javac is a symbolic
#ls -al `whereis javac`

4.use export java_home
#export JAVA_HOME=/usr/lib/jvm/java-6-openjdk/jre