编程创建一个Box类，在其中定义三个变量表示一个立方体的长、宽和高，再定义一个方法setDemo对这三个变量进行初始化，然后定义一个方法求立方体的体积。创建一个对象，求给定尺寸的立方体的体积。对这个内容的编程代码及结果实现-Programming to create a Box class, in which the three variables that define a cube of length, width and height, and then define a method setDemo these three variables initialized, and then define a method, to calculate the volume of the cube. Create an object, seeking for a given volume of the cube size. The content of this programming code and the results achieved