从数据库查询出来数据集合后,可能不是我们想要的排序顺序,比如要求按照距离、评分、订单数排序
所以就需要我们在内存中进行排序
下面是用 Collections.sort()写的一个例子
import java.util.*;
public class Test {
public static void main(String[] args) {
List<Map<String,Object>> list = new ArrayList<>();
Map<String, Object> map1 = new HashMap<>();
map1.put("name","港岛煲仔饭店");
map1.put("meter",1000);
map1.put("grade",50);
map1.put("count",99);
list.add(map1);
Map<String, Object> map2 = new HashMap<>();
map2.put("name","兰州拉面店");
map2.put("meter",1200);
map2.put("grade",44);
map2.put("count",66);
list.add(map2);
Map<String, Object> map3 = new HashMap<>();
map3.put("name","西部大盘鸡店");
map3.put("meter",600);
map3.put("grade",49);
map3.put("count",19);
list.add(map3);
sort(list,1);
System.out.println("按距离最近排序");
for (Map<String,Object> shop : list) {
System.out.println(shop.get("name")+"---"+"距您"+shop.get("meter")+"米---"+"评分:"+Float.valueOf(shop.get("grade").toString())/10+"分---"+"订单数:"+shop.get("count")+"单");
}
System.out.println();
System.out.println("按订单数最多排序");
sort(list,2);
for (Map<String,Object> shop : list) {
System.out.println(shop.get("name")+"---"+"距您"+shop.get("meter")+"米---"+"评分:"+Float.valueOf(shop.get("grade").toString())/10+"分---"+"订单数:"+shop.get("count")+"单");
}
System.out.println();
System.out.println("按评分最高排序");
sort(list,3);
for (Map<String,Object> shop : list) {
System.out.println(shop.get("name")+"---"+"距您"+shop.get("meter")+"米---"+"评分:"+Float.valueOf(shop.get("grade").toString())/10+"分---"+"订单数:"+shop.get("count")+"单");
}
}
/**
* @description: 排序
* @author: caoju
*/
public static void sort(List<Map<String,Object>> BusinessList, int type){
switch (type){
case 1:
Collections.sort(BusinessList , (o1, o2)-> {
Integer o1Value = Integer.valueOf(o1.get("meter").toString());
Integer o2Value = Integer.valueOf(o2.get("meter").toString());
return o1Value.compareTo(o2Value);
});
break;
case 2:
Collections.sort(BusinessList , (o1,o2)-> {
Integer o1Value = Integer.valueOf(o1.get("count").toString());
Integer o2Value = Integer.valueOf(o2.get("count").toString());
return o2Value.compareTo(o1Value);
});
break;
case 3:
Collections.sort(BusinessList , (o1,o2)-> {
Integer o1Value = Integer.valueOf(o1.get("grade").toString());
Integer o2Value = Integer.valueOf(o2.get("grade").toString());
return o2Value.compareTo(o1Value);
});
break;
}
}
}
看下最后执行的结果:
可以看到已经按照想排的顺序进行排序了