创建一个类Cat

包含属性name，在构造方法中进行初始化

添加一个方法show()，用以打印name属性的值

创建一个类CatTest，添加main方法，实现

创建一个ArrayList，向其中添加几个Cat对象

遍历该集合，并且对每个Cat对象调用show()方法-Create a kind of Cat

Contains attribute name, in the constructor library

Add a method show () to print name attribute values

Create a kind of CatTest, add main method, the realization

Create a ArrayList, to which added several Cat object

Traverse the set, and for each object is called Cat show () method