설치시 먼저 openjdk를 삭제한다

sudo apt-get purge openjdk*

Java7 설치를 위해 저장소를 추가한다
sudo add-apt-repository ppa:eugenesan/java
sudo apt-get update
sudo apt-get install oracle-java7-installer

설치를 하다보면 아래와 같이 오류가 발생한다

Download done.
sha256sum mismatch jdk-7u3-linux-x64.tar.gz
Oracle JDK 7 is NOT installed.
dpkg: error processing oracle-java7-installer (--configure):
 subprocess installed post-installation script returned error exit status 1
Setting up python-central (0.6.17ubuntu1) ...
Setting up python-eggtrayicon (2.25.3-11) ...
Setting up gmail-notify (1.6.1.1-1ubuntu1) ...
Processing triggers for python-central ...
Errors were encountered while processing:
 oracle-java7-installer
Error in function: 
아래와 같이 명령 실행하여 재설치 한다.
sudo rm /var/lib/dpkg/info/oracle-java7-installer*
sudo apt-get purge oracle-java7-installer*
sudo rm /etc/apt/sources.list.d/*java*
sudo apt-get update
sudo add-apt-repository ppa:webupd8team/java
sudo apt-get update
sudo apt-get install oracle-java7-installer
설치가 완료 된다^^