CODEWITHSUNDEEP
javacasting
HelloRacoon
HelloRacoon

Reputation: 97

Does upcasting ensure the preservation of a child's field in java?

I'm going to use Hibernate for a persist some entities.

EntityClass entity = new EntityClass();
Object obj = (Object) entity;
hibernateSession.persist(obj)

Can I ensure that the field value in the original EntityClass will be preserved?

Does the garbage collector not clear field values?

In all other cases, can I ensure that the upcasting preserves the value of the original field?

(other common cases that don't use hibernate)

It is my original code

Class<?> clazz = Class.forName(~~~); // from external file
Iterator<?> iterator = ((Iterator<?>) clazz.getConstructor(String.class).newInstance(~~~); // from external file

while (iterator.hasNext()) {
    for (JsonEntity content : (List<JsonEntity>) iterator.next()) {
        session.saveOrUpdate(content.toEntity());
    }
    session.flush();
}
transaction.commit();

Upvotes: 1

Views: 219

Answers (2)

czolbe
czolbe

Reputation: 611

upcasting a reference type (such as Entity) does not alter the object or it's fields. You can read more here : https://www.baeldung.com/java-type-casting

Neither does it require you to explicitly cast it since the compiler implicitly recognizes that Entity is a subclass of Object. You can simply do:

Object obj = entity;

Upvotes: 0

user3817206
user3817206

Reputation: 344

  • you don't need to cast and pass to entity object. 
EntityClass entity = new EntityClass();
hibernateSession.persist(entity);

  • as long as your entity class is being referred, will it not be garbage collection

  • casting your object to a super class will not delete the original fields/methods but you can only access fields/methods which are available in super class only

Upvotes: 1

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