可否解说一下这个程序是怎么运行的？

提问者：街角京里街  |  浏览 次  |  提问时间：2017-03-16  |  回答数量：1

interface ComputeTotalSales{public double totalSalesByYear( );}class Television implementsComputeTotalSales{ public double totalSalesByYear( ){ return 400; } // 实现totalSalesByYear( )方法}class Computer implementsComputeTotalSales{public double totalSalesByYear( ){return 1000; }// 实现totalSalesByYear( )方法}class Mobile implementsComputeTotalSales{public double totalSalesByYear( ){return 2000; }// 实现totalSalesByYear( )方法}class Shop{ComputeTotalSales[ ] goods; double totalSales=0; Shop(ComputeTotalSal