redis/jedis · error · IllegalArgumentException

HashImport fields must not contain empty names

Error message

HashImport fields must not contain empty names

What it means

HashImport.build (invoked from both of() overloads) throws IllegalArgumentException when any field is a zero-length byte array. Empty hash field names are not valid Redis hash fields, so the library rejects them while finalizing the template.

Solutions

Filter out empty entries: drop fields where field == null || field.length == 0 before calling of().
Trim/validate string inputs so no empty strings reach HashImport.of.
Check binary sources for truncation that yields zero-length buffers.

Example fix

// before
String[] parts = spec.split(","); // may include ""
HashImport t = HashImport.of(parts);
// after
String[] parts = Arrays.stream(spec.split(",")).map(String::trim).filter(s -> !s.isEmpty()).toArray(String[]::new);
HashImport t = HashImport.of(parts);

Defensive patterns

Strategy: validation

Validate before calling

boolean noEmpties = Arrays.stream(fields).allMatch(f -> f != null && !f.trim().isEmpty());
if (!noEmpties) { /* filter empties before HashImport.of */ }

Type guard

boolean nonEmpty(byte[] b) { return b != null && b.length > 0; }

Try / catch

try {
  HashImport t = HashImport.of(fields);
} catch (IllegalArgumentException e) {
  log.warn("Empty hash field name rejected: {}", e.getMessage());
}

Prevention

Trim and filter string fields before passing them to of().
Watch for split()-produced empty tokens when parsing field specs.
Check binary reads for truncation that yields zero-length arrays.

When it happens

Trigger: Calling HashImport.of("") or HashImport.of(new byte[0]); string fields that are empty after encoding produce byte[0] and fail in build.

Common situations: Empty strings from split() results (e.g. "a,,b".split(",") style logic or trailing delimiters); blank config values; truncated binary reads producing zero-length buffers.

Understand the failure class

Background: "must not be empty", "cannot be empty" — required-field validation errors across open-source libraries — this error's family across 41 libraries.

Related errors

AI-assisted analysis of redis/jedis@6dac31d4c2 (2026-09-08). Data as JSON: /api/errors/61890829fa3cc089. Report an issue: GitHub.

Appendix: source

Thrown at src/main/java/redis/clients/jedis/HashImport.java:111

  public static HashImport of(byte[]... fields) {
    if (fields == null || fields.length == 0) {
      throw new IllegalArgumentException("HashImport fields must be non-null and non-empty");
    }
    List<byte[]> copy = new ArrayList<>(fields.length);
    for (byte[] field : fields) {
      if (field == null) {
        throw new IllegalArgumentException("HashImport fields must not contain null");
      }
      copy.add(field.clone()); // clone so later caller mutation can't alter the template
    }
    return build(copy);
  }

  private static HashImport build(List<byte[]> fields) {
    Set<ByteBuffer> seen = new HashSet<>();
    for (byte[] field : fields) {
      if (field.length == 0) {
        throw new IllegalArgumentException("HashImport fields must not contain empty names");
      }
      if (!seen.add(ByteBuffer.wrap(field))) {
        throw new IllegalArgumentException("HashImport fields must not contain duplicates");
      }
    }
    return new HashImport(nextName(), Collections.unmodifiableList(fields));
  }

  /**
   * @return {@code true} once {@link #close()} has been called
   * @since 8.0
   */
  public boolean isDiscarded() {
    return discarded;
  }

  /**
   * Discards this template; it must not be used again afterwards. Server-side cleanup is deferred

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