Find the first matching stream value.
Java: Use findFirst and an explicit default for an empty result.
import java.util.*;
import java.util.stream.*;
import java.util.regex.*;
import java.nio.file.*;
import java.nio.charset.StandardCharsets;
import java.time.*;
import java.time.format.DateTimeFormatter;
import java.time.temporal.*;
import java.math.*;
import java.io.*;
import java.net.*;
import java.security.MessageDigest;
import java.util.concurrent.*;
public class Main {
public static void main(String[] args) throws Exception {
System.out.println(List.of(3, 8, 10).stream().filter(n -> n % 2 == 0).findFirst().orElse(-1));
}
}Expected output EXAMPLE
8
Details
Save as Main.java, compile with javac Main.java, and run java Main. Uses the Java 21 standard library. Use findFirst and an explicit default for an empty result.
Tested on Ubuntu 24.04.5 LTS · · openjdk 21.0.12.1 2026-08-18 · openjdk-21-jdk-headless 21.0.12.1+1-1~24.04.4
Test inputs, results and environment
The exact published code ran in a dedicated Linux test container with prepared inputs. Unprivileged snippet process, external networking disabled, read-only root filesystem, and a fresh temporary working directory. Fixtures and output records are isolated from the application database. Testing covers this example and its stated checks, not every input, operating system, or runtime version. The Linux container shares its host's kernel; this is not a native Windows test.
- Architecture / host kernel
- x86_64 / 6.18.54.1-microsoft-standard-WSL2
- Snippet identity / locale
- uid=65534, gid=65534 (unprivileged) / C.UTF-8
- Interpreter invocation
javac Main.java && java Main- Container image ID
sha256:32dc2d998158b6554c99b73b533f423696a0f3e31e8cbea9db10b5eee9a2fadd- Code SHA-256
26d66422fe1697b9d2ba381dc5bafc6ec0f73572a3cca9f7dfecbd985115c640- Dependencies
- openjdk-21-jdk-headless 21.0.12.1+1-1~24.04.4
Test input setup
These are the prepared inputs used by the test harness. See Details above for the prerequisites and how to run this example.
# No input files required.
Observed standard output
8
Exit code: 0. Standard error: empty. Validation: Exact stdout comparison. System-dependent values above are one recorded run.