java 将长键和数组列表值添加到哈希映射

adding long key and arraylist value to hashmap

提问by user1660325

I am getting db data this way

我以这种方式获取数据库数据

userid, dates

用户名、日期

1125,3-05-2013

1125,3-05-2013

1125,4-05-2013

1125,4-05-2013

1125,5-05-2013

1125,5-05-2013

200,23-05-2013

200,23-05-2013

200,24-05-2013

200,24-05-2013

I need to add these to hashmap as hashmap(userid,dates)..

我需要将这些作为 hashmap(userid,dates) 添加到 hashmap 中。

i.e: hashmap(long,arraylist(string of dates)) and send to front end.

即： hashmap(long,arraylist(string of date)) 并发送到前端。

I mean long value in hashmap should be unique, which is an key to retrive list of all dates for a particular user id,

我的意思是 hashmap 中的 long 值应该是唯一的，这是检索特定用户 ID 的所有日期列表的关键，

so if I try hashmap.get(1125) == ishould get list of all dates for user 1125 like 3-05-2013,4-05-2013,5-05-2013

所以如果我尝试hashmap.get(1125) == i应该获取用户 1125 的所有日期列表，例如 3-05-2013,4-05-2013,5-05-2013

then if I try hashmap.get(200) == ishould get list of all dates for user 200 like 23-05-2013,24-05-2013

那么如果我尝试 hashmap.get(200) == i应该获取用户 200 的所有日期列表，例如 23-05-2013,24-05-2013

I tried this way , but I am getting all the dates for single userid like,

我试过这种方式，但我得到了单个用户 ID 的所有日期，例如，

users200 dates[3-05-2013, 4-05-2013, 5-05-2013, 23-05-2013, 24-05-2013]

users200 日期[3-05-2013, 4-05-2013, 5-05-2013, 23-05-2013, 24-05-2013]

Here is my code,

这是我的代码，

// TODO Auto-generated method stub

        List<User> myEmpls = new ArrayList<User>();

        User User1 = new User();
        User1.setEmpcode((long) 1125);
        User1.setDate("3-05-2013");
        myEmpls.add(User1);

        User User2 = new User();
        User2.setEmpcode((long) 1125);
        User2.setDate("4-05-2013");
        myEmpls.add(User2);

        User User5 = new User();
        User5.setEmpcode((long) 1125);
        User5.setDate("5-05-2013");
        myEmpls.add(User5);

        User User3 = new User();
        User3.setEmpcode((long) 200);
        User3.setDate("23-05-2013");
        myEmpls.add(User3);

        User User4 = new User();
        User4.setEmpcode((long) 200);
        User4.setDate("24-05-2013");
        myEmpls.add(User4);



        long prevUser=0;
        int cnt=1;
        long users =0;
        ArrayList<ArrayList<String>> lists = new ArrayList<ArrayList<String>>();
        HashMap<Long, ArrayList> finalmap =  new HashMap<>();
        ArrayList<String> dates = new ArrayList<>();
        for(User time : myEmpls)
        {
            if(prevUser==time.getEmpcode())
            {
                users = time.getEmpcode();
                System.out.println("users"+users);
                dates.add(time.getDate());
            }
            else
            {
                dates.add(time.getDate());
            }
            System.out.println("dates"+dates);
            finalmap.put(users, lists);
            prevUser =  time.getEmpcode();
            cnt++;
        }

can some one help me in this issue?

有人可以帮助我解决这个问题吗？

回答by Markus Mikkolainen

Map<Long,ArrayList<String>> map=new HashMap<Long,ArrayList<String>>();
public void addToMap(long id,String blaa)
{
     ArrayList<String> ar=map.get(id)
     if(ar==null)
     {
          ar=new ArrayList<String>();
          map.put(id,ar);
     }
     ar.add(blaa);
}

is this what you want? just call this for each row you receive

这是你想要的吗？只需为您收到的每一行调用它

回答by mlwacosmos

Do like that... it is more simple :

这样做...更简单：

class User {
    private Long id;
    private String date;

    public User(Long id, String date) {
        this.id = id;
        this.date = date;
    }

    public Long getId() {
        return this.id;
    }

    public String getDate() {
        return this.date;
    }
}

List<User> listUsers = new ArrayList<User>();
listUsers.add(new User(new Long(2500), "03/05/2013"));
listUsers.add(new User(new Long(2500), "04/05/2013"));
listUsers.add(new User(new Long(2500), "05/05/2013"));
listUsers.add(new User(new Long(200), "10/05/2013"));
listUsers.add(new User(new Long(200), "18/05/2013"));

HashMap<Long, ArrayList> map = new HashMap<Long, ArrayList>();

for(User user : listUsers) {        
    if(map.containsKey(user.getId())) {
        map.get(user.getId()).add(user.getDate());
    } else {
        ArrayList<String> dates = new ArrayList<String>();
        dates.add(user.getDate());
        map.put(user.getId(), dates);
    }
}

//just to check
System.out.println("number of keys : " + map.size());
System.out.println("number of dates for 2500 : " + map.get(new Long(2500)).size());
System.out.println("number of dates for 200 : " + map.get(new Long(200)).size());

回答by Satya

Use something like this:

使用这样的东西：

  HashMap<Long, ArrayList> finalmap =  new HashMap<Long, ArrayList>();
 for(User obj : myEmpls){

        if(finalmap.containsKey(obj.getEmpcode())){
            ArrayList<String> dates = finalmap.get(obj.getEmpcode());
            dates.add(obj.getDate());
            finalmap.put(obj.getEmpcode(), dates);
        }else{
            ArrayList<String> dates = new ArrayList<String>();
            dates.add(obj.getDate());
            finalmap.put(obj.getEmpcode(), dates);
        }

    }