LinkedHashSet .equals() vs LinkedList .equals() with same elements but different order

Question

Consider the following SSCCE:

public static void main(String[] args) {
    LinkedHashSet set1 = new LinkedHashSet<>();
    set1.add(\"Bob         


        

Answer 1

As mentioned above: LinkedHashSet extends HashSet which extends AbstractSet which implements equals method: https://docs.oracle.com/javase/8/docs/api/java/util/AbstractSet.html#equals-java.lang.Object-

Compares the specified object with this set for equality. Returns true if the given object is also a set, the two sets have the same size, and every member of the given set is contained in this set. This ensures that the equals method works properly across different implementations of the Set interface.

The easiest way to compare LinkedHashSet if order if important to you is to serialize it and compare them then:

    LinkedHashSet reverseOrder = new LinkedHashSet<>();
    reverseOrder.add(2);
    reverseOrder.add(1);
    LinkedHashSet ordered = new LinkedHashSet<>();
    ordered.add(1);
    ordered.add(2);
    System.out.println("Equals via set: " + ordered.equals(reverseOrder));
    System.out.println("Equals With Arrays: " + ordered.ordered.toString().equals(reverseOrder.ordered.toString()));

Result:

Equals via Set: true
Equals With Arrays: false