Types

The Types class provides methods for retrieving generic type information, converting types, and handling parameterized types. These methods facilitate efficient and convenient manipulation of Java types at runtime.

Methods

1. getActualType(Type type)

Retrieves the actual type arguments of a parameterized type.

• Parameters:
  • type: The type to retrieve the actual type arguments from.
• Returns: An array of Type representing the actual type arguments, or null if the input type is not a parameterized type.

Example:

Type type = new ParameterizedType() {
    @Override
    public Type[] getActualTypeArguments() {
        return new Type[]{String.class};
    }

    @Override
    public Type getRawType() {
        return List.class;
    }

    @Override
    public Type getOwnerType() {
        return null;
    }
};
Type[] actualType = Types.getActualType(type);
// actualType will contain String.class

2. getGenericReturnType(Method method)

Retrieves the actual type arguments of a method's return type.

• Parameters:
  • method: The method to retrieve the return type from.
• Returns: An array of Type representing the actual type arguments of the return type.

Example:

Method method = TestTypes.class.getMethods()[0];
Type[] actualType = Types.getGenericReturnType(method);
// actualType will contain the generic return type of the method

3. getGenericFirstReturnType(Method method)

Retrieves the first actual type argument of a method's return type and converts it to a Class.

• Parameters:
  • method: The method to retrieve the return type from.
• Returns: The first actual type argument as a Class, or null if the return type is not parameterized.

Example:

Method method = TestTypes.class.getMethods()[0];
Class<?> actualType = Types.getGenericFirstReturnType(method);
// actualType will be the first generic return type of the method as a Class

4. getActualType(Class<?> clz)

Retrieves the actual type arguments of a class's superclass.

• Parameters:
  • clz: The class to retrieve the actual type arguments from.
• Returns: An array of Type representing the actual type arguments of the class's superclass.

Example:

Type[] actualType = Types.getActualType(ArrayList.class);
// actualType will contain the generic type arguments of ArrayList's superclass

5. getActualClass(Class<?> clz)

Retrieves the first actual type argument of a class's superclass and converts it to a Class.

• Parameters:
  • clz: The class to retrieve the actual type argument from.
• Returns: The first actual type argument as a Class.

Example:

Class<?> actualClass = Types.getActualClass(ArrayList.class);
// actualClass will be the first generic type argument of ArrayList's superclass as a Class

6. type2class(Type type)

Converts a Type to a Class.

• Parameters:
  • type: The Type to convert.
• Returns: The Class representation of the Type, or null if the Type is not a Class.

Example:

Type type = String.class;
Class<?> actualClass = Types.type2class(type);
// actualClass will be String.class