Sum integer values.
Reduce a Java integer stream to its sum.
import java.util.*;
import java.nio.file.*;
import java.nio.charset.StandardCharsets;
public class Main {
public static void main(String[] args) throws Exception {
System.out.println(List.of(2, 3, 5).stream().mapToInt(Integer::intValue).sum());
}
}Expected output EXAMPLE
10
Details
Save as Main.java. Compile with javac Main.java, then run java Main. Uses only the Java standard library; tested with OpenJDK 21.
Integer sums can overflow; choose a larger numeric type when needed.
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
615b278d6ce9712485dc736245164a95abbc97f7ed511f147168eebcb5ab92b4- 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
10
Exit code: 0. Standard error: empty. Validation: Exact stdout comparison. System-dependent values above are one recorded run.