上代码:
java
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
public class day10 {
public static void main(String[] args) {
List<Map<String,Object>> list = new ArrayList<>();
Map<String,Object> map1 = new HashMap<>();
map1.put("region","西安");
map1.put("num",3.3);
Map<String,Object> map2 = new HashMap<>();
map2.put("region","上海");
map2.put("num",4.0);
Map<String,Object> map3 = new HashMap<>();
map3.put("region","北京");
map3.put("num",5.4);
Map<String,Object> map4 = new HashMap<>();
map4.put("region","西安");
map4.put("num",6.4);
Map<String,Object> map5 = new HashMap<>();
map5.put("region","西安");
map5.put("num",6.4);
Map<String,Object> map6 = new HashMap<>();
map6.put("region","北京");
map6.put("num",6.4);
Map<String,Object> map7 = new HashMap<>();
map7.put("region","成都");
map7.put("num",6.4);
Map<String,Object> map8 = new HashMap<>();
map8.put("region","上海");
map8.put("num",2.0);
Map<String,Object> map9 = new HashMap<>();
map9.put("region","上海");
map9.put("num",2.0);
Map<String,Object> map10 = new HashMap<>();
map10.put("region","上海");
map10.put("num",2.0);
list.add(map1);
list.add(map2);
list.add(map3);
list.add(map4);
list.add(map5);
list.add(map6);
list.add(map7);
list.add(map8);
list.add(map9);
list.add(map10);
System.out.println("入参list:"+list);
/*
* 思路:
* 创建两个Map:
* Map1(地域,相同地域num值加和);
* Map2(地域,相同地域统计次数累计);
*
* 循环数据,通过containsKey判断是否包含key,
* 包含:Map1 相同地域num值加和存进去;Map2 相同地域统计次数累计存进去;
* 不包含:Map1和Map2直接存;
*
*
*/
// Map存储:(region,num),num为相同region的加和;
Map<String,Object> regionMap = new HashMap<>();
// Map存储:(region,统计次数),统计次数为相同region的次数;
Map<String,Object> countMap = new HashMap<>();
for (int i = 0; i < list.size(); i++) {
String region = String.valueOf(list.get(i).get("region"));
String num = String.valueOf(list.get(i).get("num"));
// regionMap包含region:将region当作key;
if(regionMap.containsKey(region)) {
String key = region;
String value = String.valueOf(regionMap.get(key)); // 从regionMap获取value值;即地域对应的num值;
regionMap.put(region, Double.parseDouble(value) + Double.parseDouble(num));
}
else { // 不包含,直接存进去
regionMap.put(region, num);
}
// countMap包含region:将region当作key;
if(countMap.containsKey(region)) {
String key2 = region;
String value2 = String.valueOf(countMap.get(key2)); // 从countMap获取value值;即地域对应的统计次数值;
countMap.put(region, Integer.valueOf(value2) + 1);
}
else { // 不包含,直接存进去
countMap.put(region, 1);
}
}
System.out.println("regionMap:"+regionMap);
System.out.println("countMap:"+countMap);
List<String> regionList = new LinkedList<String>(); // 地域
List<String> numberList = new LinkedList<String>(); // 数值
List<String> countList = new LinkedList<String>(); // 统计次数
List<String> avgList = new LinkedList<String>(); // 平均值
// 封装地域集合:(北京,5.9)
Iterator<Map.Entry<String, Object>> it = regionMap.entrySet().iterator();
while(it.hasNext()){
Map.Entry<String, Object> entry = it.next();
String key = entry.getKey();
String value = String.valueOf(entry.getValue());
regionList.add(key);
numberList.add(value);
}
// 封装统计次数集合:(北京,1)
Iterator<Map.Entry<String, Object>> it2 = countMap.entrySet().iterator();
while(it2.hasNext()){
Map.Entry<String, Object> entry = it2.next();
String key = entry.getKey();
String value = String.valueOf(entry.getValue());
countList.add(value);
}
// 计算平均值:封装集合avgList
if(numberList.size() == countList.size()) {
for (int i = 0; i < numberList.size(); i++) {
double fenzi = Double.parseDouble(numberList.get(i));
int fenmu = Integer.valueOf(countList.get(i));
if(fenmu > 0) {
Double x = fenzi/fenmu;
// double类型的数据当分母的数值趋近0的时候,返回来的数值就是一个NAN:
if(Double.isNaN(x)){
x = 0.0;
}
avgList.add(String.valueOf(x));
}
}
}
System.out.println("regionList:"+regionList);
System.out.println("numberList:"+numberList);
System.out.println("countList:"+countList);
System.out.println("avgList:"+avgList);
// 最终输出集合:
List<Map<String,Object>> resultList = new ArrayList<>();
// 根据地域集合与平均值集合封装新集合resultList:
if(regionList.size() == avgList.size()) {
for (int i = 0; i < regionList.size(); i++) {
Map<String,Object> map = new HashMap<>();
map.put("title",regionList.get(i));
map.put("value",avgList.get(i).substring(0,avgList.get(i).indexOf(".")+2));
resultList.add(map);
}
}
System.out.println("最终输出集合resultList:"+resultList);
//排序:value值大的Map往前排,斌且插入新字段:sortValue,代表序列;
Double[] valueSort = new Double[resultList.size()];
String[] titleSort = new String[resultList.size()];
// 排序后最终输出集合:
List<Map<String,Object>> listFinal= new ArrayList<>();
// 获取排序的数组:
for (int i = 0; i < resultList.size(); i++) {
valueSort[i] = Double.parseDouble(String.valueOf(resultList.get(i).get("value")));
titleSort[i] = String.valueOf(resultList.get(i).get("title"));
}
// 数组排序:
BubblSortUtils.bubbleSortDescMultipleDouble(valueSort,titleSort);
// 数组封装listFinal:
for (int i = 0; i < valueSort.length; i++) {
String ch = String.valueOf(titleSort[i]);
for (int j = 0; j < resultList.size(); j++) {
String value = String.valueOf(resultList.get(j).get("title"));
if(ch.equals(value)){
listFinal.add(resultList.get(j));
}
}
}
// listFinal中添加排序字段:sortValue
for (int i = 0; i < listFinal.size(); i++) {
listFinal.get(i).put("sortValue",i+1);
}
System.out.println("最终排序后输出集合listFinal:"+listFinal);
}
}
测试输出:
java
入参list:[{num=3.3, region=西安}, {num=4.0, region=上海}, {num=5.4, region=北京}, {num=6.4, region=西安}, {num=6.4, region=西安}, {num=6.4, region=北京}, {num=6.4, region=成都}, {num=2.0, region=上海}, {num=2.0, region=上海}, {num=2.0, region=上海}]
regionMap:{成都=6.4, 上海=10.0, 西安=16.1, 北京=11.8}
countMap:{成都=1, 上海=4, 西安=3, 北京=2}
regionList:[成都, 上海, 西安, 北京]
numberList:[6.4, 10.0, 16.1, 11.8]
countList:[1, 4, 3, 2]
avgList:[6.4, 2.5, 5.366666666666667, 5.9]
最终输出集合resultList:[{title=成都, value=6.4}, {title=上海, value=2.5}, {title=西安, value=5.3}, {title=北京, value=5.9}]
最终排序后输出集合listFinal:[{sortValue=1, title=成都, value=6.4}, {sortValue=2, title=北京, value=5.9}, {sortValue=3, title=西安, value=5.3}, {sortValue=4, title=上海, value=2.5}]