Find the First Odd Number from a List in Java

Problem:
Using Java 8 Streams, how do you find the first odd number in a list efficiently, without manually looping?

✅ Example:

import java.util.Arrays;
import java.util.List;
import java.util.Optional;

public class FirstOddNumber {

    public static void main(String[] args) {
        List<Integer> numbers = Arrays.asList(2, 4, 6, 8, 17, 9, 24, 19);

        Optional<Integer> firstOdd = numbers.stream()  // Use stream(), parallelStream() is not necessary here
                .filter(element -> element % 2 != 0)  // Filter odd numbers
                .findFirst();  // Find the first matching element

        firstOdd.ifPresent(System.out::println);
    }
}

✅ Output:

17

✅ ✅ Explanation:

1. We create a list of numbers: [2, 4, 6, 8, 17, 9, 24, 19]
2. We use .stream() (sequential stream is sufficient for this purpose): numbers.stream()
3. .filter(ele -> ele % 2 != 0) filters all odd numbers:
   • Result after filtering: [17, 9, 19].
4. .findFirst() returns the first element in encounter order, wrapped in Optional<Integer>.
5. We print the result using: firstOdd.ifPresent(System.out::println);

✅ Important Note:

• Avoid using .parallelStream() here because it may not guarantee order in finding the first element.
  Always prefer .stream() when order matters.