CODEWITHSUNDEEP
javajava-8
Suvitruf - Andrei Apanasik
Suvitruf - Andrei Apanasik

Reputation: 5672

Remove elements from original list after filtering

For example, in C# I can select elements from original list:

List<string> result = first_mas.Where(d => d == "1").First().ToList();

And if I remove elements from result, same elements also will be removed from first_mas.

In Java I can do something like this:

List<String> result = first_mas.stream().filter(d -> d.equals("1")).collect(Collectors.toList());

But if I remove elements from result they will not be removed from original array.

Is it possible to remove elements from original list after filtering?

UPD:

public void doSomething(List<String> list){
    // here remove something from list, should also be removed from original list
    // i don't have link to original list here
}

doSomething(first_mas.stream().filter(d -> d.get(0).equals("1")).collect(Collectors.toList()));

Upvotes: 2

Views: 1785

Answers (3)

fps
fps

Reputation: 34460

You should use the Collection.removeIf(predicate) method.

According to the docs:

Removes all of the elements of this collection that satisfy the given predicate.

In your example:

first_mas.removeIf(d -> d.equals("1"));

Or better:

first_mas.removeIf("1"::equals);

In case you do need to do this inside the doSomething(List<String> list) method, just pass the original list as an argument.

Upvotes: 0

Marco Stramezzi
Marco Stramezzi

Reputation: 2271

Probably I do not understand well your question, but why can't you pass the list to doSomething and then manipulate it with Lambdas?

Something like this:

public static void main(String[] args) {
    List<String> l = new ArrayList<>();
    l.add("a");
    l.add("b");
    System.out.println(l.size());
    doSomething(l);
    System.out.println(l.size());
}

private static void doSomething(List<String> l) {
    l.stream().filter(s -> s.equals("a")).findFirst().map(l::remove);
}

Upvotes: 0

Bahramdun Adil
Bahramdun Adil

Reputation: 6079

You can try this:

List<String> original;
original.removeAll(result);

When you get the result, then you can easily remove all the elements which are in the result List

Upvotes: 3

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