mybatis/mybatis-3 · error · IllegalArgumentException

{} does not represent an enum type.

Error message

{} does not represent an enum type.

What it means

EnumOrdinalTypeHandler validates that the Class passed to its constructor is really an enum by calling type.getEnumConstants(); a null return means the class is not an enum type, and the handler aborts with this IllegalArgumentException naming the offending class.

Source

Thrown at src/main/java/org/apache/ibatis/type/EnumOrdinalTypeHandler.java:38

import java.sql.ResultSet;
import java.sql.SQLException;

/**
 * @author Clinton Begin
 */
public class EnumOrdinalTypeHandler<E extends Enum<E>> extends BaseTypeHandler<E> {

  private final Class<E> type;
  private final E[] enums;

  public EnumOrdinalTypeHandler(Class<E> type) {
    if (type == null) {
      throw new IllegalArgumentException("Type argument cannot be null");
    }
    this.type = type;
    this.enums = type.getEnumConstants();
    if (this.enums == null) {
      throw new IllegalArgumentException(type.getSimpleName() + " does not represent an enum type.");
    }
  }

  @Override
  public void setNonNullParameter(PreparedStatement ps, int i, E parameter, JdbcType jdbcType) throws SQLException {
    ps.setInt(i, parameter.ordinal());
  }

  @Override
  public E getNullableResult(ResultSet rs, String columnName) throws SQLException {
    int ordinal = rs.getInt(columnName);
    if (ordinal == 0 && rs.wasNull()) {
      return null;
    }
    return toOrdinalEnum(ordinal);
  }

  @Override

View on GitHub (pinned to 008069adb1)

Solutions

1. Register the handler only for actual enum types: verify Class.isEnum() (or @Alias target) before registering
2. Fix the javaType value in the configuration to point at the real enum class
3. For constant-holder classes (public static final ints), use a regular type handler, not an enum handler

Example fix

// before
<typeHandler handler="...EnumOrdinalTypeHandler" javaType="com.example.StatusHolder"/>

// after
<typeHandler handler="...EnumOrdinalTypeHandler" javaType="com.example.Status"/> // real enum

if (!SomeClass.class.isEnum()) {
  throw new IllegalArgumentException(SomeClass.class.getName() + " is not an enum; cannot use an enum TypeHandler");
}

static boolean isEnumType(Class<?> c) { return c != null && c.isEnum(); }

When it happens

Trigger: Registering EnumOrdinalTypeHandler (or EnumTypeHandler) for a plain class — a class containing enum-like constants, an interface, or a non-enum POJO specified via javaType= or defaultEnumTypeHandler.

Common situations: Setting <setting name="defaultEnumTypeHandler" .../> to EnumOrdinalTypeHandler while the model also contains non-enum classes; mistyping the javaType so it resolves to a wrapper or interface instead of the enum.

Related errors

• Type argument cannot be null
• Type argument cannot be null
• Failed to invoke constructor {}
• '{}' does not implement TypeHandler.
• Type {typeHandlerType} is not a valid TypeHandler because it

AI-assisted analysis of mybatis/mybatis-3@008069adb1 (2026-08-14). Data as JSON: /api/errors/b261ddbe0dcc6756. Report an issue: GitHub.