How can I combine two lists of maps so that only the unique values in the list remain? I thought about doing some nested for loops to compare the two lists, but it seems a bit messy. Is there a better way to do this.

Obviously just adding to the list doesn't give me unique values. MapList.addAll(mapList2);

1 Answer 1


A Set<Map<String, String>> can contain and deduplicate Map<String, String> by their contents. When working with Set, keep in mind how it determines object identity:

Uniqueness of all other non-primitive types is determined by comparing the objects’ fields.

As an illustration, you can do

Set<Map<String, String>> s = new Set<Map<String, String>>();

Map<String,String> m1 = new Map<String, String> {
    'Test' => 'Foo'

Map<String,String> m2 = new Map<String, String> {
    'Test' => 'Foo'

System.debug('s contains m2? ' + String.valueOf(s.contains(m2)));

You'll get back true; the two Map instances are considered equal because they have the same field values.

You can get a deduplicated Set<Map<String, String>> from a two List<Map<String, String>> objects by doing

Set<Map<String, String>> s = new Set<Map<String, String>>(myList);

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .