Any Java collection for comparing datasets

Question

I have 2 data sets for 2 months with student names and grades.

I need to provide February grades for each student and a percentage change with his / her feb grades.

Can I do this using the Java collection?

Dataset example:

name Jan_score Feb_score John 40 80 Mary 61 81 Jim 52 82 Liz - 84 Tim 94 -

The output should look like this:

(Name: John, Feb_score: 80, percent change: 100)
(Name: Mary, Feb_score: 81, percent change: 32.76)
(Name: Jim, Feb_score: 82, percent change: 57.69)
(Name: Liz, Feb_score: 84 , percent change: not determined)
(Name: Tim, Feb_score: -, percent change: not determined)

Answer 1

HashMap :

        HashMap<String, ArrayList<Integer>> studentMap=new HashMap<String, ArrayList<Integer>>();

- , - . 0 ArrayList , 1 feb ( ).

, ,

    scores=new ArrayList<Integer>();
    scores.add(40);
    scores.add(80);
    studentMap.put("John", scores);

    scores=new ArrayList<Integer>();
    scores.add(61);
    scores.add(81);
    studentMap.put("Mary", scores);

,

for(String name : studentMap.keySet())
    {
        ArrayList<Integer> scoreList=studentMap.get(name);

        System.out.println("Name : "+name+"     Jan Score: "+scoreList.get(0)+"     Feb Score : "+scoreList.get(1));
    }

.

Answer 2

Java, . . , , .

Answer 3

( = , value = ). , , .

To calculate the percentage change, follow these steps:

1) Iterations over all elements in the February map (say, the current student is a student)

2) Look for Student rating 'stu' on the January map.

3) Calculate the percentage change.

Answer 4

To do this, you can use TreeSet, and you create another class in one package and implement the “Comparator Interface” to compare two objects and pass it when creating TreeSet objects.