CODEWITHSUNDEEP
javasorting
JavaDeveloper
JavaDeveloper

Reputation: 5660

How to sort an list of references?

I have a list of linkedlist's node. Basically references to node objects. Some of the references point to the same object. Now my question is on how to sort them.

Input :

List< node1, node3, node 4, node1, node2, node3>

Output:

List <node1, node1, node2, node3, node3, node4>

Order could be arbitraty ie List <node3, node3, node2, node4, node1, node1>, but atleast the adjacent nodes should be next to each other.

Also note, the sorting is not based on 'node value' but simply based on node references.

MORE REFERENCE:

I have a map, Map <headNode, tailNode>. Since the linkedlist can intersect the map contains unique heads but does not contain unique tails. My intention is to sort the map based on 'value' and then walk through map with logic similar to if (tail at pos i != tail @ pos i + 1) then the 2 linkedlist done intersect and print them.

Upvotes: 2

Views: 149

Answers (2)

JNL
JNL

Reputation: 4713

If you are plan to eliminate the duplicates, why don't you use HashSet

Upvotes: 1

arshajii
arshajii

Reputation: 129537

You can sort based on the System.identityHashCode() value of each element in the list. You can implement a Comparator as follows:

enum IdentitySort implements Comparator<Node> {
    INSTANCE;

    @Override
    public int compare(Node n1, Node n2) {
        return Integer.compare(System.identityHashCode(n1),
                               System.identityHashCode(n2));
    }
}

Then, you can use Collections.sort():

Collections.sort(list, IdentitySort.INSTANCE);

Upvotes: 2

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