set up eclipse && java on ubuntu

Above are very good and complete method. and they are from website 2 day geek

Install java :

1. Download jdk tar from oracle website , and uncompress it to a filefolder (such as /opt)
2. set environment variables for java. there are three methods. 

• system wide. edit /etc/profile or create a new *.sh in /etc/profile.d/(this method is better). then edit java.sh as below.  

1. export JAVA_HOME=/opt/jdk1.8.0_60 
2. export CLASSPATH=$CLASSPATH:$JAVA_HOME/lib:$JAVA_HOME/jre/lib
3. export PATH=$PATH:$JAVA_HOME/bin:$JAVA_HOME/jre/bin

          then save the .sh file and run command "source /etc/proflile"

• single user . edit .bashrc (which is in ~/). we can use export just as above . or use alias as below

1. alias java=/opt/jdk1.8.0_60/bin/java
2. alias javac=.....

          then save file .bashrc and run command "source ~/.bashrc"

• just in this session. just use export as above.