重学java（二）-优快云博客

本文介绍了如何在Java中创建一个简单的数学库，通过封装常用的数学函数来提升代码复用性和效率。从创建项目、编写基本的加法方法、导出为.jar文件，再到在目标项目中引入并使用该库，实现了一个从概念到实践的完整流程。

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Code reuse is one of the most important factors in software development. It is a very good idea to put frequently-used functions together and build a library for yourself. Whenever some method is used, just simply make a method invocation.

For Java, it’s straightforward to manage such a library. Here a simple example in Eclipse.

The library will contain only one “add” method.

Step 1: Create a “Java Project” named as “MyMath”, and a simple “add” method under “Simple” class.

Package structure is as follows:

Simple.java

public class Simple {
	public static int add(int a, int b){
		return a+b;
	}
}

Step 2: Export as a .jar file.

Right Click the project and select “export”, a window is show as follows.

Following the wizard, to get the .jar file.

Step 3: Use the jar file.

Right click the target project, and select “Build Path”->”Add External Archives”->following wizard to add the jar file.

Now you can make a simple method call.

public class Main {
	public static void main(String[] args) {
		System.out.println(Simple.add(1, 2));
	}
}