0. Introduction
JDK = Java Development Kit (http://en.wikipedia.org/wiki/JDK)
Used for java develop, eclipse(java, c++, jee, php, javascript etc)
1. Environment
Ubuntu 10.04
JDK 6.27 (jdk-6u27-linux-i586.bin), please do not use rpm version, becase the ubuntu does not support rpm version
2. Steps
1) Create a empty folder where you want to install JDK (for example, I choose /home/yineng/program, but in formal, you can choose /usr, because the folder /usr in Linux is like the folder Program Files in Windows)
2) Move JDK installation file(jdk-6u27-linux-i586.bin) to the folder you create in step 1, because the JDK will be installed where you run the JDK installation file exists
3) Add the executable permission to the installation file using the following command
$ sudo chmod +x jdk-6u27-linux-i586.bin
4) Install JDK with the command
$ ./jdk-6u27-linux-i586.bin
5) Config environment variable
5.1) open /etc/environment file with command
$ sudo gedit /etc/environment
5.2) In the end of file, add following lines (/home/yineng/program is the folder where I installed the JDK, you should replace it with your direction)
PATH="/home/yineng/program/jdk1.6.0_27/bin"
JAVA_HOME="/home/yineng/program/jdk1.6.0_27"
CLASSPATH=".:/home/yineng/program/jdk1.6.0_27/lib"
6) Restart your computer and have fun with the JDK, and you can test your JDK version with command
$ java -version
3. Reference
http://wenku.baidu.com/view/956b86360b4c2e3f57276371.html