Java平台的划分

要彻底了解Java 2 Micro Edition，我们必须先对Java 2 Micro Edition在整个Java技术之中的定位做个了解。

一般我们在撰写C程序的时候，会使用C标准程序库；使用C++撰写程序的时候，会使用C++标准程序库；而使用Java撰写程序的时候，则使用Sun所提供的Java标准类库。之所以叫做类库，是因为各式各样的方法（method，也可以叫做“函数”）被有系统地放在类之中，而这些类又被分门别类地归属在不同的包（package）之下，相较起来，传统标准程序库（例如Win32 API）的组成结构就显得有点松散。

这些各式各样的包（package），组成了所谓的核心类库（Core Class，即java.*），在核心类库之外还有所谓的扩充类库（Extended Class，即javax.*）。程序员可以自由选用各种程序库来完成自己的工作。

Java语言还支持8种基本类型（primitive type，即boolean、byte、short、int、long、float、double），可供程序员撰写程序时使用。根据所支持的基本类型，以及对这些核心和扩充类库所支持的程度，Sun Microsystems区分出四种不同的Java平台，如图1-1所示。-By Java Platform

To thoroughly understand the Java 2 Micro Edition, we must first of the Java 2 Micro Edition Java technology into the entire understanding of the positioning to be.

In general we write a C program, will use the C standard library　using C++ written program, will use the C++ Standard Library　and use Java to write programs when you use the Sun provided by the Java standard library. The reason is called the library, because a variety of methods (method, also called a "function") have been systematically put into classes, which classes they are categorized in a different package ownership (package) s under comparison, the traditional standard library (such as Win32 API) of the structure becomes a bit loose.

These kinds of packages (package), form the so-called core class libraries (Core Class, the java .*), there are the so-called outside of the core library extension library (Extended Class, or javax .*) . Programmers are free to choose a variety of library to comp