Join strings with a separator.
Build a Java string from several values using String.join.
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(String.join(" / ", "red", "green", "blue"));
}
}Expected output EXAMPLE
red / green / blue
Details
Save as Main.java. Compile with javac Main.java, then run java Main. Uses only the Java standard library; tested with OpenJDK 21.
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
9ad84d27ca40a6e9375c09d86fc5a463b3d643c542c40e876b4838f91b222654- 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
red / green / blue
Exit code: 0. Standard error: empty. Validation: Exact stdout comparison. System-dependent values above are one recorded run.