Remove elements from List of objects by comparing with another array in Java

Question

I have a list of subscriptions

subscriptions = [
      { 
        code : "Heloo",
        value:"some value",
        reason : "some reason"
      },
      { 
        code : "Byeee",
        value:"some byee",
        reason : "some byee"
      },
      { 
        code : "World",
        value:"some World",
        reason : "some world"
      }
    ]

I have another list of unsubscriptions:

unsubscribe : ["Heloo","World"]

I want to unsubscribe elements in the subscriptions by comparing these two arrays

Final Result :

subscriptions = [
  { 
    code : "Byeee",
    value:"some byee value",
    reason : "some byee reason"
  }
]

Below is my solution :

List<String> newList = new ArrayList<>();
for (String products : subscriptions) {
        newList.add(products.code);
 }

if (!newList.containsAll(unsubscribe) {
        log.error("Few products are not subscribed");  
}

for (int i = 0; i < subscriptions.size(); i++) {
        if(unsubscribe.contains(subscriptions.get(i).code)) {
          subscriptions.remove(i);
        }
}

This could be better . I am looking for a better/optimized solution.

It's readable and it works. How many subscription do you need to handle that you think you need something more optimized? — Federico klez Culloca
– Federico klez Culloca, Commented Aug 28, 2020 at 10:06
@VishwaRatna First of all, please calm down. Second, OP didn't ask about any of those in particular. Those are in the answers, not in the question. Also, generics are used in the question. Should we add a java-5 tag as well? — Federico klez Culloca
– Federico klez Culloca, Commented Aug 28, 2020 at 10:37
@Federico klez Culloca : I have created an array new list of just the codes to check if newList contains all the items to unsubscribe. Could this be done in a better way instead of creating a new list ? — MOFD
– MOFD, Commented Aug 28, 2020 at 10:53

Mureinik · Accepted Answer · 2020-08-28 10:09:26Z

3

Using removeIf will clean up your code considerably:

List<Subscription> subscriptions =  ... ;
List<String> unsubscribe = ...;

subscriptions.removeIf(s -> unsubscribe.contains(s.code));

answered Aug 28, 2020 at 10:09

Mureinik

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Comments

sergiomse · Accepted Answer · 2020-08-28 10:12:07Z

0

You can also do it with streams:

List<String> newList = subscriptions
                                 .stream()
                                 .filter(it -> !unsubscribe.contains(it.code))
                                 .collect(Collectors.toList());

answered Aug 28, 2020 at 10:12

sergiomse

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