Question

JAVA Question

a) Write a generic method

public static <...> Collection<Pair<...>> sortPairCollection(Collection <Pair<....>> col)

in a Utils class that takes as parameter a collection of Pair<K,V> objects
and returns a new collection object (use ArrayList<...>) with the pair elements from collection col
sorted in ascending order. For comparing pairs, the K type must implement Comparable<....>
Use the proper type constraints.

b)
Write a main() function in Utils.java that tests the sortPairCollection() with K=String and V=Integer.

Answer 1

import javafx.util.Pair;

import java.util.ArrayList;
import java.util.Collection;

public class Utils {

    public static <K extends Comparable<K>, V> Collection<Pair<K, V>> sortPairCollection(Collection <Pair<K, V>> col) {
        Collection<Pair<K, V>> sorted = new ArrayList<>();
        while (!col.isEmpty()) {
            Pair<K, V> min = null;
            for(Pair<K, V> pair: col) {
                if(min == null || pair.getKey().compareTo(min.getKey()) < 0) {
                    min = pair;
                }
            }
            sorted.add(min);
            col.remove(min);
        }
        return sorted;
    }

    public static void main(String[] args) {
        Collection<Pair<String, Integer>> collection = new ArrayList<>();
        collection.add(new Pair<>("ronaldo", 7));
        collection.add(new Pair<>("messi", 10));
        collection.add(new Pair<>("bale", 11));
        collection.add(new Pair<>("isco", 23));
        Collection<Pair<String, Integer>> sorted = sortPairCollection(collection);
        System.out.println(sorted);
    }

}

[bale-11, isco-23, messi-10, ronaldo-7] Process finished with e xit code 0