这个课程的参考视频在youtube。
主要学到的知识点有：
- Create new project, choose Java Application.
- one .jar file/ package(.jar name with the same as package), one package can contains mutiple .java files.
- Comment mutiple lines by using "/* */"; comment one line by using "//"
/*
* This is example to comment mutliple lines
*/ // This is one line comment
- A class is the template from which objects are created.
- Object: Instance of a class.
- public can be accessed by other class and private can not.
- static means that you can use it without define it first. (also allow method to been used by other class without define an object)
- void mens return nothing, like in C.
- Statements should end with ;