How to convert code to generic method - Object.class

laprof :

I want to convert my entities to data access objects and I don't want to create a method for every entity. How can I convert my code into a generic method with generic return Entity and param ObjectDTO?

private ConcreteEntity convertToEntity(ConcreteObjectDTO objectDTO) throws ParseException {
    ConcreteEntity entity = modelMapper.map(objectDTO, ConcreteEntity.class);
    return entity;
}

I wrote the following code, but I don't know how to handle Entity.class

private <Entity, ObjectDTO> Entity convertToEntity(ObjectDTO objectDTO) throws ParseException {
    Entity entity = modelMapper.map(objectDTO, Entity.class);
    return entity;
}

John Kugelman :

Your method will need to take a Class instance as a parameter so it can forward the right class to modelMapper.map(). That means Class<E> where E extends Entity. Note that it's convention to give generic types single letter names.

Similarly, the ObjectDTO should also be genericized as O extends ObjectDTO or equivalent.

private <O extends ObjectDTO, E extends Entity> E convertToEntity(O objectDTO, Class<E> entityClass) throws ParseException {
    return modelMapper.map(objectDTO, entityClass);
}

You may be able to skip genericizing the DTO parameter. It's probably not necessary.

private <E extends Entity> E convertToEntity(ObjectDTO objectDTO, Class<E> entityClass) throws ParseException {
    return modelMapper.map(objectDTO, entityClass);
}