mybatis/mybatis-3 · error · ReflectionException

There is no default constructor for {}

Error message

There is no default constructor for {}

What it means

Reflector.getDefaultConstructor() throws when the reflected class has no public no-arg constructor. MyBatis instantiates result types, parameter types, and typeHandler-owning classes through this path, and without a default constructor it cannot create the instance.

Source

Thrown at src/main/java/org/apache/ibatis/reflection/Reflector.java:371

      return false;
    }
    return true;
  }

  /**
   * Gets the name of the class the instance provides information for.
   *
   * @return The class name
   */
  public Class<?> getType() {
    return clazz;
  }

  public Constructor<?> getDefaultConstructor() {
    if (defaultConstructor != null) {
      return defaultConstructor;
    }
    throw new ReflectionException("There is no default constructor for " + clazz);
  }

  public boolean hasDefaultConstructor() {
    return defaultConstructor != null;
  }

  public Invoker getSetInvoker(String propertyName) {
    Invoker method = setMethods.get(propertyName);
    if (method == null) {
      throw new ReflectionException("There is no setter for property named '" + propertyName + "' in '" + clazz + "'");
    }
    return method;
  }

  public Invoker getGetInvoker(String propertyName) {
    Invoker method = getMethods.get(propertyName);
    if (method == null) {
      throw new ReflectionException("There is no getter for property named '" + propertyName + "' in '" + clazz + "'");

View on GitHub (pinned to 008069adb1)

Solutions

1. Add a public no-arg constructor to the class (plus @NoArgsConstructor alongside Lombok @AllArgsConstructor).
2. Map through a constructor instead: <constructor> elements in the resultMap, or argNameBasedConstructorAutomapping/autoMappingBehavior, so MyBatis uses the arg-taking constructor.
3. For immutable objects, use a custom ObjectFactory or a TypeHandler/ResultHandler that builds the object yourself.

Example fix

// before
@AllArgsConstructor
public class User { private final Long id; }
// after
@NoArgsConstructor
@AllArgsConstructor
public class User { private Long id; }

boolean instantiable = new ReflectorFactory().createForType(User.class).hasDefaultConstructor();
if (!instantiable) { /* add no-arg ctor or map via <constructor> */ }

When it happens

Trigger: A resultType/parameterType class (or javaType handled by a factory) whose only constructors take arguments, reached via ObjectFactory.create(type) during result mapping or parameter processing.

Common situations: DTOs with only an all-args constructor (common with Lombok @AllArgsConstructor without @NoArgsConstructor); Kotlin data classes without a no-arg constructor (or kotlin-noarg plugin); immutable value objects.

Related errors

• Error instantiating {} with invalid types ({}) or values ({}
• Cannot set value of property '{}' because '{}' is null and c
• Unable to find a usable constructor for {}
• Error creating instance. Cause: {cause}
• Error in result map '{resultMapId}'. Failed to find a constr

AI-assisted analysis of mybatis/mybatis-3@008069adb1 (2026-08-14). Data as JSON: /api/errors/36af1def0f0e16c8. Report an issue: GitHub.