@Delimiter¶

Sets the delimiter for the ListObjects request used to query S3.

Declaration¶

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface Delimiter {
    String value();
}

Attributes¶

Description¶

S3 uses delimiters to simulate a directory hierarchy within a flat key space. The default delimiter is "/", which treats slashes in keys as directory separators. @Delimiter allows changing this for keys that use a different separator.

@Delimiter works on both immediate listing methods and @Recursive methods. When used with @Recursive, the delimiter controls how the walk discovers child prefixes at each level.

Examples¶

Flat listing with a custom delimiter¶

public interface Logs extends S3.Dir {
    // Keys like "2025-01-15-access.log", "2025-01-15-error.log"
    @Delimiter("-")
    Stream<S3File> bySegment();
}

Recursive listing with a custom delimiter¶

public interface DateIndex extends S3.Dir {
    // Keys like "2025-01-15", "2025-02-20"
    // Delimiter "-" splits on hyphens, creating a year/month/day hierarchy
    @Recursive
    @Delimiter("-")
    Stream<S3.Dir> byDate();
}

No delimiter¶

An empty string disables delimiter-based grouping entirely:

public interface Bucket extends S3.Dir {
    // Returns all keys as a flat list, no directory grouping
    @Delimiter("")
    Stream<S3File> allKeys();
}

See Also¶

• @Recursive — recursive listing (defaults to "/" delimiter for S3.Dir types)
• Listing & Recursion — how delimiters affect listings