List>操做(遍歷，比較)

時間 2019-11-11

標籤 list 遍歷比較简体版

原文原文鏈接

1.List<Map<String,String>>的遍歷：java

Map<String,String> map = new HashMap<String, String>();  

    map.put("1", "fds");  
    map.put("2", "valu");  
    List<Map<String, String>> list = new ArrayList<Map<String, String>>();  
    list.add(map);  
    for (Map<String, String> m : list){  
      for (String k : m.keySet()){  
        System.out.println(k + " : " + m.get(k));  
      }  
   
    }

　2.兩個List<Map<String,String>>相互比較，有相同數據時某些字段相加減blog

inOrderList與outOrderList放本身的所比較的數據,name,number,id爲map的key值ci

for (int i = 0; i < inOrderList.size(); i++) {//循環獲取入庫數據
	    String number1 = String.valueOf(inOrderList.get(i).get("number"));
            String depotName1 = inOrderList.get(i).get("name");
            String proId1 = inOrderList.get(i).get("id");
            for (int j = 0; j < outOrderList.size(); j++) {//循環獲取出庫數據
            	 String number2 = String.valueOf(outOrderList.get(j).get("number"));
                 String depotName2 = outOrderList.get(j).get("name");
                 String proId2 = outOrderList.get(j).get("id");
                if (depotName1.equals(depotName2) && proId1.equals(proId2)) {
                	Integer sum =Integer.parseInt(number1) - Integer.parseInt(number2);//判斷是否爲同一條數據，同條數據數量相減
                    inOrderList.get(i).put("number", sum + "");
                }
            }
        }

3.單個List<Map<String,String>>相互比較，相同數據相加(轉)rem


 List<Map<String, String>> l = new ArrayList<Map<String,String>>();
        Map<String, String> m1 = new HashMap<String, String>();
         
        m1.put("count", "1");
        m1.put("name", "幫寶適紙尿褲L164 超薄幹爽夏季透氣專用嬰兒尿不溼");
        m1.put("province", "江蘇省");
        m1.put("date", "2014-09-23 10:13:39");
        m1.put("channel", "東環大潤發");
        m1.put("city", "蘇州市");
        l.add(m1);
         
        Map<String, String> m2 = new HashMap<String, String>();
        m2.put("count", "1");
        m2.put("name", "幫寶適紙尿褲L164 超薄幹爽夏季透氣專用嬰兒尿不溼");
        m2.put("province", "江蘇省");
        m2.put("date", "2014-09-23 10:13:39");
        m2.put("channel", "東環大潤發");
        m2.put("city", "泰州市");
        l.add(m2);
         
        Map<String, String> m3 = new HashMap<String, String>();
        m3.put("count", "1");
        m3.put("name", "幫寶適紙尿褲L164 超薄幹爽夏季透氣專用嬰兒尿不溼");
        m3.put("province", "江蘇省");
        m3.put("date", "2014-09-23 10:13:39");
        m3.put("channel", "東環大潤發");
        m3.put("city", "泰州市");
        l.add(m3);
         
        List<Map<String, String>> countList = new ArrayList<Map<String,String>>();//用於存放最後的結果
        for (int i = 0; i < l.size(); i++) {
            String count = l.get(i).get("count");
            String name = l.get(i).get("name");
            String province = l.get(i).get("province");
            String date = l.get(i).get("date");
            String channel = l.get(i).get("channel");
            String city = l.get(i).get("city");
             
            int flag = 0;//0爲新增數據，1爲增長count
            for (int j = 0; j < countList.size(); j++) {
                String count_ = countList.get(j).get("count");
                String name_ = countList.get(j).get("name");
                String province_ = countList.get(j).get("province");
                String date_ = countList.get(j).get("date");
                String channel_ = l.get(j).get("channel");
                String city_ = countList.get(j).get("city");
                 
                if (count.equals(count_)&&
                        name.equals(name_)&&
                        province.equals(province_)&&
                        date.equals(date_)&&
                        channel.equals(channel_)&&
                        city.equals(city_)) {
                    int sum = Integer.parseInt(l.get(i).get("count")) + Integer.parseInt(countList.get(j).get("count"));
                    countList.get(j).put("count", sum + "");
                    flag = 1;
                    continue;
                }
            }
            if (flag == 0) {
                countList.add(l.get(i));
            }
        }
        for (Map<String, String> map : countList) {
            System.out.println(map);
        }
    }


public class Test {
 
    /**
     * @param args
     */
    public static void main(String[] args) {
        List<Map<String, String>> list = new ArrayList<Map<String,String>>();
        Map<String,String> map1 = new HashMap<String,String>();
        map1.put("count", "1");
        map1.put("name", "幫寶適紙尿褲L164 超薄幹爽夏季透氣專用嬰兒尿不溼");
        map1.put("province", "江蘇省");
        map1.put("date", "2014-09-23 10:13:39");
        map1.put("channel", "東環大潤發");
        map1.put("city", "蘇州市");
        list.add(map1);
         
        Map<String,String> map2 = new HashMap<String,String>();
        map2.put("count", "1");
        map2.put("name", "幫寶適紙尿褲L164 超薄幹爽夏季透氣專用嬰兒尿不溼");
        map2.put("province", "江蘇省");
        map2.put("date", "2014-09-23 10:13:39");
        map2.put("channel", "東環大潤發");
        map2.put("city", "泰州市");
        list.add(map2);
         
        Map<String,String> map3 = new HashMap<String,String>();
        map3.put("count", "1");
        map3.put("name", "幫寶適紙尿褲L164 超薄幹爽夏季透氣專用嬰兒尿不溼");
        map3.put("province", "江蘇省");
        map3.put("date", "2014-09-23 10:13:39");
        map3.put("channel", "東環大潤發");
        map3.put("city", "泰州市");
        list.add(map3);
         
         
        Map<String,String> map4 = new HashMap<String,String>();
        map4.put("count", "1");
        map4.put("name", "幫寶適紙尿褲L164 超薄幹爽夏季透氣專用嬰兒尿不溼");
        map4.put("province", "江蘇省");
        map4.put("date", "2014-09-23 10:13:39");
        map4.put("channel", "東環大潤發");
        map4.put("city", "蘇州市");
        list.add(map4);
         
        System.out.println(mergeList(list));
         
         
    }
 
     
    /**
     * 合併相同的Map
     * @param list
     * @return
     */
    public static List<Map<String,String>> mergeList(List<Map<String,String>> list){
        List<Map<String,String>> retList = new ArrayList<Map<String,String>>();
        for(int i=0;i<list.size();i++){
            Map<String,String> map = list.get(i);
            String name = map.get("name");
            String city = map.get("city");
            String count = map.get("count");
            Map<String,String> newMap=isExistSame(i,name,city,count,list);
            if(null==newMap){
                retList.add(map);
            }
            else{
                list.remove(map.get(i));
                retList.add(newMap);
            }
        }
        return retList;
    }
     
    private static Map<String,String> isExistSame(int i,String name,String city,String count,List<Map<String,String>> list){
        Map<String,String> newMap = null;
        for(int j=i+1;j<list.size();j++){
            Map<String,String> innerMap = list.get(j);
            String name1 = innerMap.get("name");
            String city1 = innerMap.get("city");
            String count1 = innerMap.get("count");
            if(name.equals(name1)&&city.equals(city1)){
                newMap = new HashMap<String,String>();
                newMap.put("count", ""+(Integer.parseInt(count)+Integer.parseInt(count1)));
                Iterator<String> keyIterator = innerMap.keySet().iterator();
                while(keyIterator.hasNext()){
                    String key = keyIterator.next();
                    if(!key.equals("count")){
                        newMap.put(key, innerMap.get(key));
                    }
                }
                list.remove(j);
            }
        }
        return newMap;
    }
}

ublic static void main(String[] args) {
        List<Map<String, String>> list = new ArrayList<Map<String,String>>();
        boolean m = true;
        for(int i=0;i<10000;i++){
            HashMap<String, String> map = new HashMap<String, String>();
            map.put("count", "1");
            map.put("name", "幫寶適紙尿褲L164 超薄幹爽夏季透氣專用嬰兒尿不溼");
            map.put("province", "江蘇省");
            map.put("date", "2014-09-23 10:13:39");
            map.put("channel", "東環大潤發");
            map.put("city", m ? "蘇州市":"泰州市");
            m = !m;
            list.add(map);
        }
        System.out.println(System.currentTimeMillis());
        for(int i=list.size();--i>-1;){
            Map<String, String> src = list.get(i);
            int same = 0;
            for(int j=i-1;j>-1;j--){
                Map<String, String> tar = list.get(j);
                if(equals(src, tar)){
                    int count = Integer.parseInt(src.get("count"))
                            +Integer.parseInt(tar.get("count"));
                    src.put("count", count+"");
                    list.remove(j);
                    same++;
                }
            }
            i -=same;
        }
        System.out.println(list);
        System.out.println(System.currentTimeMillis());
    }
     
    public static boolean equals(Map<String, String> src,Map<String, String> tar){
        Set<Entry<String,String>> entrySet = src.entrySet();
        String srcCount = src.remove("count");//count不參與比較
        String srcValue = null,tarValue = null;
        for (Iterator<Entry<String,String>> it = entrySet.iterator(); it.hasNext();) {
            Entry<String, String> entry = it.next();
            srcValue = entry.getValue();
            tarValue = tar.get(entry.getKey());
            if(srcValue.length()!=tarValue.length()||!srcValue.equals(tarValue)){
                src.put("count", srcCount);
                return false;
            }
        }
        src.put("count", srcCount);
        return true;
    }

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