check your security or cracked.

1. jdk, jre 다운로드

http://www.oracle.com/technetwork/java/javase/downloads/index.html

jdk-7u21-linux-i586.tar.gz (32-bit)

jre-7u21-linux-i586.tar.gz (32-bit)

or

jdk-7u21-linux-x64.tar.gz (64-bit)

jre-7u21-linux-x64.tar.gz (64-bit)

2-a. 32BIT 에서

cd /home/"your_user_name"/Downloads

sudo -s mkdir /usr/local/java

sudo -s cp -r jdk-7u21-linux-i586.tar.gz /usr/local/java

sudo -s cp -r jre-7u21-linux-i586.tar.gz /usr/local/java

cd /usr/local/java

sudo -s tar xvzf jdk-7u21-linux-i586.tar.gz

sudo -s tar xvzf jre-7u21-linux-i586.tar.gz

2-b 64BIT 에서

cd /home/"your_user_name"/Downloads

sudo -s mkdir /usr/local/java

sudo -s cp -r jdk-7u21-linux-x64.tar.gz /usr/local/java

sudo -s cp -r jre-7u21-linux-x64.tar.gz /usr/local/java

cd /usr/local/java

sudo -s tar xvzf jdk-7u21-linux-x64.tar.gz

sudo -s tar xvzf jre-7u21-linux-x64.tar.gz

3. 환경변수 설정.

sudo vi /etc/profile

JAVA_HOME=/usr/local/java/jdk1.7.0_21

PATH=$PATH:$HOME/bin:$JAVA_HOME/bin

JRE_HOME=/usr/local/java/jre1.7.0_21

PATH=$PATH:$HOME/bin:$JRE_HOME/bin

export JAVA_HOME

export JRE_HOME

export PATH

를 추가하고 저장.

4. 우분투 패키지 관리자에 자바 바이너리 설정시키기.

sudo update-alternatives --install "/usr/bin/java" "java" "/usr/local/java/jre1.7.0_21/bin/java" 1

sudo update-alternatives --install "/usr/bin/javac" "javac" "/usr/local/java/jdk1.7.0_21/bin/javac" 1

sudo update-alternatives --install "/usr/bin/javaws" "javaws" "/usr/local/java/jre1.7.0_21/bin/javaws" 1

5. 우분투 패키지 관리자에 default로 인식되게 설정하기

sudo update-alternatives --set java /usr/local/java/jre1.7.0_21/bin/java

sudo update-alternatives --set javac /usr/local/java/jdk1.7.0_21/bin/javac

sudo update-alternatives --set javaws /usr/local/java/jre1.7.0_21/bin/javaws

6. 재부팅 후, 설치 확인

sudo shutdown -r now

java -version

출처  : http://www.wikihow.com/Upgrade-Oracle-Java-on-Ubuntu-Linux