Question

How can I create a list (or some other type of container) of integer and strings pairs that allows duplicates in both pairs and can be sorted by the integer value?

I need to fill a container with names (string) and scoring (integer) pairs, the container must allow duplicated values in both name and scoring, and i need to sort this list by the scoring value.

I tried with a SortedMap but doesn’t allow duplicated values:

SortedMap<Integer,String> sm=new TreeMap<Integer, String>();

sm.put(23, "Peter");  
sm.put(11, "Tony");  
sm.put(110, "Claire");  
sm.put(13, "ferca");  
sm.put(55, "Julian");  
sm.put(13, "Pedro");  

In this example, ferca and Pedro have the same scoring value, this is something I need to allow, but the SortedMap overwrites “ferca” with “Pedro”.

What is the best container type to do this?

Answer 1

Since you want your collection to be ordered, I suggest you use a List and Collections.sort. If you decide to go for this approach you still have two options:

• Create a custom Comparator that can be passed as an argument to sort, or
• Let the auxiliary Score class implement Comparable<Score>

Here is an example and ideone demo of the latter approach:

import java.util.*;

class Score implements Comparable<Score> {
    int score;
    String name;

    public Score(int score, String name) {
        this.score = score;
        this.name = name;
    }

    @Override
    public int compareTo(Score o) {
        return score < o.score ? -1 : score > o.score ? 1 : 0;
    }
}

public class Test {

    public static void main(String[] args){
        List<Score> scores = new ArrayList<Score>();

        scores.add(new Score(23, "Peter"));  
        scores.add(new Score(11, "Tony"));  
        scores.add(new Score(110, "Claire"));  
        scores.add(new Score(13, "ferca"));  
        scores.add(new Score(55, "Julian"));  
        scores.add(new Score(13, "Pedro"));

        Collections.sort(scores);
    }
}