Compare two sets of Objects in Java

Question

I have two sorted sets : sortedSet1(Object ,Object1 , Object2 , Object3 , Object4 ) and sortedSet2(Object ,Object1 , Object2 , Object3 , Object4 ) . The objects have other lists with objects inside.

I want to compare each value from inside out and catch any differences between the 2 sortedSets. I do not want the exact difference. I want to see just if there are any changes. I have tried sortedSet1.equals(sortedSet2) but it dies not work, if i change a value inside another object inside the sortedSet it does not catch the difference. I have also tried

if (!sortedSet1.containsAll(sortedSet2)) {
    // do something 
}

with no luck.. I think that the answer exists in streams, but I have very little experience with them..

Thank you very much for your help.

how are the sets defined? what is the generic type of the items? how deep is the nesting of lists? do list items contain lists themselves??? — Sharon Ben Asher, Mar 06 '19 at 07:47
1) it doesn't work is too broad. Give a specific example that could help us to provide some hints and answers 2) Set equality relies on equals() of the elements contained in. — davidxxx, Mar 06 '19 at 07:49
@Filip123go please do refer this https://stackoverflow.com/questions/4085353/comparing-two-collections-in-java — Ashok Kumar N, Mar 06 '19 at 07:56
I know that it is to broad. And i do not know how deep it could go. It depends on the occasion. — Filip123go, Mar 06 '19 at 08:09

score 1 · Accepted Answer · answered Mar 06 '19 at 08:01

if i change a value inside another object inside the sortedSet it does not catch the difference

First to find the differences would be something like:

SortedSet<Object> common = new TreeSet<>(sortedSet1);
common.retainAll(sortedSet2);
SortedSet<Object> all = new TreeSet<>(sortedSet1);
all.addAll(sortedSet2);
SortedSet<Object> differences = new TreeSet<>(all);
differences.removeAll(common);

However your mention of changing an object once inside the set, rings an alarm.

One should never change a value so that its used key (hashCode or here Comparable) changes. As then the ordering and structural location is corrupted. For a tree structure parts of the tree become inaccessible as the left subtree is assumed to be less than the node's key, and the right subtree should have nodes greater than the node's key.

This helped a lot, I can continue from here. Thanks everyone for their help and their time! — Filip123go, Mar 06 '19 at 08:12

Compare two sets of Objects in Java

1 Answers1