Java Collection Comparison

compare1.java

public class Elem { 
    public String key; 
    public String value; 
    public Elem (String key, String value) {
        this.key = key;
        this.value = value;
    }
    public boolean equals(Object o) {
        Elem other = (Elem) o;
        return key.equals(other.key)
            && value.equals(other.value);
    }
}

Elem e1 = new Elem("one", "1");
Elem e2 = new Elem("two", "2");

Elem e3 = new Elem("one", "1");
Elem e4 = new Elem("two", "2");

List<Elem> l1 = new ArrayList<>(Arrays.asList(e1, e2));
List<Elem> l2 = new ArrayList<>(Arrays.asList(e3, e4));

l1.equals(l2); // true

compare2.java

public class Elem { 
    public String key; 
    public String value; 
    public Elem (String key, String value) {
        this.key = key;
        this.value = value;
    }
    public boolean equals(Object o) {
        Elem other = (Elem) o;
        return key.equals(other.key)
            && value.equals(other.value);
    }
}

public class ElemComparator implements Comparator<Elem> {
    @Override
    public int compare(Elem a, Elem b) {
        return a.key.compareTo(b.key);
    }
}

Elem e1 = new Elem("one", "1");
Elem e2 = new Elem("two", "2");

Elem e3 = new Elem("one", "1");
Elem e4 = new Elem("two", "2");

List<Elem> l1 = new ArrayList<>(Arrays.asList(e1, e2));
List<Elem> l2 = new ArrayList<>(Arrays.asList(e4, e3));

l1.sort(new ElemComparator());
l2.sort(new ElemComparator())

l1.equals(l2); // true