Converting singly linked list to a map

Question

I have been given an assignment to change to upgrade an existing one.

Figure out how to recode the qualifying exam problem using a Map for each terminal line, on the assumption that the size of the problem is dominated by the number of input lines, not the 500 terminal lines

The program takes in a text file that has number, name. The number is the PC number and the name is the user who logged on. The program returns the user for each pc that logged on the most. Here is the existing code

public class LineUsageData {
    SinglyLinkedList<Usage> singly = new SinglyLinkedList<Usage>();


    //function to add a user to the linked list or to increment count by 1
    public void addObservation(Usage usage){
        for(int i = 0; i < singly.size(); ++i){
            if(usage.getName().equals(singly.get(i).getName())){
                singly.get(i).incrementCount(1);
                return;
            }
        }

        singly.add(usage);
    }
    //returns the user with the most connections to the PC
    public String getMaxUsage(){
        int tempHigh = 0;
        int high = 0;
        String userAndCount = "";
        for(int i = 0; i < singly.size(); ++i){//goes through list and keeps highest
            tempHigh = singly.get(i).getCount();
            if(tempHigh > high){
                high = tempHigh;
                userAndCount = singly.get(i).getName() + " " + singly.get(i).getCount();
            }
        }

        return userAndCount;
    }
}

I am having trouble on the theoretical side. We can use a hashmap or a treemap. I am trying to think through how I would form a map that would hold the list of users for each pc? I can reuse the Usage object which will hold the name and the count of the user. I am not supposed to alter that object though

Answer 1

I Solved this offline and didn't get a chance to see some of the answers which looked to be both very helpful. Sorry about that Nick and Aivean and thanks for the responses. Here is the code i ended up writing to get this to work.

public class LineUsageData {

    Map<Integer, Usage> map = new HashMap<Integer, Usage>();
    int hash = 0;
    public void addObservation(Usage usage){
        hash = usage.getName().hashCode();
        System.out.println(hash);
        while((map.get(hash)) != null){
            if(map.get(hash).getName().equals(usage.name)){
                map.get(hash).count++;
                return;
            }else{
                hash++;
            }

        }
        map.put(hash, usage);
    }






    public String getMaxUsage(){
        String str = "";
        int tempHigh = 0;
        int high = 0;

    //for loop
        for(Integer key : map.keySet()){
            tempHigh = map.get(key).getCount();
            if(tempHigh > high){
                high = tempHigh;
                str = map.get(key).getName() + " " + map.get(key).getCount();
            }
        }

        return str;
    }


}