first,there are some default jdk in system.
when we get the java 1.7.0 foldel,we should use it to instead of the default jdk.
so just use sudo update-alternatives --install... to do it.
java linux jdk(yanzheng),布布扣,bubuko.com
原文：http://www.cnblogs.com/mcdullsiin/p/3825638.html