List＜Map＜String,Object＞＞根据from和to多个字段去重，并且根据指定字段num求和

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我是靠谱客的博主碧蓝便当，最近开发中收集的这篇文章主要介绍List＜Map＜String,Object＞＞根据from和to多个字段去重，并且根据指定字段num求和，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

**//未处理数据前**
{sum=1134.0, from=8323544701622021896, to=8468946001390570465}
{sum=27.0, from=8323544701622021896, to=8468946001390570465}
{sum=11.0, from=8323544701622021896, to=8468946001390570465}
{sum=30.0, from=5743690555326549403, to=8468946001390570465}
{sum=36.0, from=8323544701622021896, to=8468946001390570465}
{sum=1291.0, from=8323544701622021896, to=8468946001390570465}
{sum=11.0, from=6357948542166894975, to=8468946001390570465}
{sum=19.0, from=8323544701622021896, to=8468946001390570465}
{sum=2.0, from=6357948542166894975, to=8468946001390570465}

**//处理数据后**
{sum=1134.0 + 27.0 + 36.0 + 1291.0 +19.0 +  32.0, from=8323544701622021896, to=8468946001390570465}
{sum=30.0, from=5743690555326549403, to=8468946001390570465}
{sum=13.0, from=6357948542166894975, to=8468946001390570465}

//创建测试数据
List<Map<String, Object>> list = new ArrayList<>();
        Map<String, Object> maps = new HashMap<>();
        Map<String, Object> map1 = new HashMap<>();
        Map<String, Object> map2 = new HashMap<>();
        Map<String, Object> map3 = new HashMap<>();
        Map<String, Object> map4 = new HashMap<>();
        Double a1 = 1134.0;
        Double b = 27.0;
        Double c = 30.0;
        Double d = 11.0;
        Double e = 81071.0;
        maps.put("from", "8323544701622021896");
        maps.put("to", "8468946001390570465");
        maps.put("sum", a1);
        map1.put("from", "8323544701622021896");
        map1.put("to", "8468946001390570465");
        map1.put("sum", b);
        map2.put("from", "5743690555326549403");
        map2.put("to", "8468946001390570465");
        map2.put("sum", c);
        map3.put("from", "6357948542166894975");
        map3.put("to", "8468946001390570465");
        map3.put("sum", d);
        map4.put("from", "5509372442598951778");
        map4.put("to", "8468946001390570465");
        map4.put("sum", e);
        list.add(maps);
        list.add(map1);
        list.add(map2);
        list.add(map3);
        list.add(map4);

解析数据第一种方法

Map<HashMap<String, String>, Double> mapMap = new HashMap<>();
        for (Map<String, Object> map : list) {
            String from = (String) map.get("from");
            String to = (String) map.get("to");
            HashMap<String, String> hashMap = new HashMap<>();
            hashMap.put("from", from);
            hashMap.put("to", to);
            if (!mapMap.containsKey(hashMap)) {
                mapMap.put(hashMap, (Double) map.get("sum"));
            } else {
                Double sum = mapMap.get(hashMap);
                Double sum1 = (Double) map.get("sum");
                mapMap.put(hashMap, sum + sum1);
            }
        }
        System.out.println(mapMap.toString());
        List<Map<String, Object>> edgesListMap = new ArrayList<>();
            for (HashMap<String, String> hashMap : mapMap.keySet()) {
                Map<String, Object> edgesMap = new HashMap<>(8);
                edgesMap.put("sum", mapMap.get(hashMap));
                edgesMap.put("from", hashMap.get("from"));
                edgesMap.put("to", hashMap.get("to"));
                edgesListMap.add(edgesMap);
            }

方法中少new资源，所以第一种的解析数据可以替换

//需要替换的代码
List<Map<String, Object>> edgesListMap = new ArrayList<>();
            for (HashMap<String, String> hashMap : mapMap.keySet()) {
                Map<String, Object> edgesMap = new HashMap<>(8);
                edgesMap.put("sum", mapMap.get(hashMap));
                edgesMap.put("from", hashMap.get("from"));
                edgesMap.put("to", hashMap.get("to"));
                edgesListMap.add(edgesMap);
            }
 //替换后的代码
 List<Map<String, Object>> list1 = new ArrayList<>();
        Set<HashMap<String, String>> set = mapMap.keySet();
        Iterator iter = set.iterator();

        while (iter.hasNext()) {
            HashMap<String, String> mapMapkey = (HashMap<String, String>) iter.next();
            String from = mapMapkey.get("from");
            String to = mapMapkey.get("to");
            Double sum = mapMap.get(mapMapkey);
            HashMap<String, Object> finalMap = new HashMap<>();
            finalMap.put("from", from);
            finalMap.put("to", to);
            finalMap.put("sum", sum);
            list1.add(finalMap);
        }

第二种方法

//创建实体类 和main方法一个文件
class A {

    private String from;
    private Double num;
    private String to;

    public A() {
    }

    public A(String from, Double num, String to) {
        this.from = from;
        this.num = num;
        this.to = to;
    }

    public String getFrom() {
        return from;
    }

    public void setFrom(String from) {
        this.from = from;
    }

    public Double getNum() {
        return num;
    }

    public void setNum(Double num) {
        this.num = num;
    }

    public String getTo() {
        return to;
    }

    public void setTo(String to) {
        this.to = to;
    }

第三种(解析数据)

List<A> inList = new ArrayList<>();
        for (Map<String, Object> mapNodes : list) {
            A a = new A();
            a.setFrom(mapNodes.get("from").toString());
            a.setTo(mapNodes.get("to").toString());
            a.setNum((Double) mapNodes.get("sum"));
            inList.add(a);
        }
        Map<String, A> map = new HashMap<>();
        inList.forEach(item -> {
            String key = item.getFrom() + ";" + item.getTo();
            if (map.containsKey(key)) {
                A a = map.get(key);
                a.setNum(a.getNum() + item.getNum());
                map.put(key, a);
            } else {
                map.put(key, item);
            }
        });
        List<A> collect = map.values().stream().collect(Collectors.toList());
        System.out.println(collect);
    }