I want to get an element (NOT the index) from a Java list using a callback.
In JavaScript, there is the Array.prototype.find method that does exactly that.
For example:
let match = [1, 2, 3, 4, 5].find((num) => num === 3);
console.log(match); // 3
Is there a Java equivalent?
You can do so using Java Stream API.
import java.util.List;
public class Main {
public static void main(String[] args) {
int x = List.of(10, 20, 30, 40, 50).stream().filter(n -> (n == 30)).findAny().orElse(-1);
System.out.println(x);
int y = List.of(10, 20, 30, 40, 50).stream().filter(n -> (n == 3)).findAny().orElse(-1);
System.out.println(y);
}
}
Output:
30
-1
Use findAny() or findFirst() depending on your requirement.
You can do the same in Java using lamda function:
Optional<Integer> result = Arrays.stream (array).filter(num -> (num==3)).findAny();
result.ifPresent(num -> System.out.println(name));
Have you tried
list.stream().filter(n -> n == 3 ).findFirst().ifPresent(n -> doSomething(n))
?
If you're trying to determine if a number exists in an array or collection you can simply use IntStream#filter.
int value = IntStream.of(1, 2, 3, 4, 5).filter(v -> v == 3).findAny().orElse(-1);
I Kinda found what i was looking for on this site - https://www.baeldung.com/find-list-element-java
Basically this:
Object item = someList
.stream()
.filter(i -> i.getName().equalsIgnoreCase(name))
.findAny()
.orElse(null);
if (item != null) {
// ...
}