CODEWITHSUNDEEP
javafilterjava-8java-stream
Christian
Christian

Reputation: 7429

How to collect the value directly from a stream -> filter of a list?

Given is a list of Strings that needs to be filtered. I know that the result is always one String. I want to get this value. Is there a better solution than doing this

List<String> bla = new ArrayList();
bla
 .stream()
 .filter(s->s.equals("something"))
 .collect(Collectors.toList())
 .get(0);

Something like getOrDefault would be awesome.

Upvotes: 2

Views: 11460

Answers (3)

Vasu
Vasu

Reputation: 22402

You can use findFirst which returns Optional object and then use Optional.orElseGet to set your default value.

Optional<String> optString = bla.stream()
         .filter(s->s.equals("something")).findFirst();

String somethingValue = optString.orElseGet(() -> "DEFAULT_VALUE");

Also, I strongly suggest, not to directly invoke the get() method as it will throw NoSuchElementException, look here for details, but you can use orElseGet as shown above.

Upvotes: 3

Raman Sahasi
Raman Sahasi

Reputation: 31841

You can use .findFirst().

But since you're sure that there will be only 1 element in the list that you're searching for, then you can use .findFirst() or .findAny() which returns an Optional.

You can then get your object by simply calling get() of this Optional class.

List<String> bla = new ArrayList();

String bla2 = bla
    .stream()
    .filter(s -> s.equals("something"))
    .findAny()
    .get();

System.out.println(bla2);

Example

import java.util.stream.*;
import java.util.*;

public class HelloWorld {
    public static void main(String[] args) {
        List < String > bla = new ArrayList();
        bla.add("one");
        bla.add("something");
        bla.add("two");

        String bla2 = bla
            .stream()
            .filter(s -> s.equals("something"))
            .findAny()
            .get();

        System.out.println(bla2);
    }
}

Output

something

Upvotes: 2

Shridhar Sangamkar
Shridhar Sangamkar

Reputation: 87

Rather than using

bla.stream() .filter(s->s.equals("something")) .collect(Collectors.toList()) .get(0);

You can use the following

bla .stream() .filter(s->s.equals("something")) .collect(Collectors.toList());

get(0) is not required

Upvotes: -2

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