参考教程:https://www3.ntu.edu.sg/home/ehchua/programming/howto/JDK_HowTo.html
1.准备工作&基础命令
// display the current JDK version
javac -version
// display the jre version
java -version
// display the location of java compiler
which javac
// display the location of java runtime
which java
2.(如果java已经预安装,则跳过此步)jdk安装
http://www.oracle.com/technetwork/java/javase/downloads/index.html
3. 写一个hello world