1.定义实体类
public class Commodity {//种类、名称、价格、商家名称、月均销量private String type;private String name;private double price;private String shopName;private int sales;public Commodity() {}public Commodity(String type, String name, double price, String shopName, int sales) {this.type = type;this.name = name;this.price = price;this.shopName = shopName;this.sales = sales;}//此处省略类属性的get set方法public String toString(){return "名称："+this.getName()+",\t售价："+this.getPrice()+",\t卖家："+this.getShopName()+",\t月销量："+this.getSales();}}
2.自定义排序的类
必须实现Comparator接口，按照类的sales销量排序
boolean 表示升序还是降序，false降序 true升序
public class SalesComparator implements Comparator<Commodity> {boolean is_Ascend;public SalesComparator(boolean b){this.is_Ascend = b;}public int compare(Commodity com1,Commodity com2) {if(is_Ascend) {return (int)(com1.getSales()-com2.getSales());}else {return (int)(com2.getSales()-com1.getSales());}}}
3.main主程序调用sort方法
public static void main(String[] args) {//准备一个集合，添加一些对象ArrayList<Commodity> powedList = new ArrayList<>();//忽略添加对象的过程powedList.add...........//排序Collections.sort(powedList,new SalesComparator(false));//显示粉饼销量前3名System.out.println("\n粉饼分析结果如下：");for (int i =0 ;i<powedList.size();i++){System.out.println("销售量第"+(i+1)+"名的是："+powedList.get(i).toString());}}
