Java（1）：Java常识

1. Differences between package and project
   A project is an IDE-level grouping; its a set of source files, configurations, assets, ect. that make up a working application.
   A package, on the other hand, is a grouping of related classes/source files. It is a way of organizing your code, and also works as the addressing scheme used by Java to find code you are importing.

2. eclipse代码补全

3. jdk和eclipse的区别
   jdk 是java的运行环境 开发包 必不可少的，
   Eclipse 是开发java的一个工具。
   jdk和Eclipse的关系如下：
   JDK是 Java 语言的软件开发工具包，主要用于移动设备、嵌入式设备上的java应用程序。JDK是整个java开发的核心，它包含了JAVA的运行环境（JVM+Java系统类库）和JAVA工具。
   Eclipse的运行依赖于jdk和jre。 jdk是编译环境（编译器），把java文件编译成class文件。 jre是运行环境（运行器），执行class文件需要使用jre。

4. 类型
   

5. Members Access Levels
   

6. java.lang Provides classes that are fundamental to the design of the Java programming language.

7. println()自带换行