如何确定扩展抽象类的对象的类

Question

I am trying to place common functionality for JPA entities in an Abstract class:

@MappedSuperclass
public abstract class AbstractEntity implements java.io.Serializable {
    private static final Logger log = LoggerFactory.getLogger(ConcreteClass.class);

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;

private UUID uuid;

@Override
public int hashCode() {
    return getUuid().hashCode();
}
@Override
public boolean equals(final Object obj) {
    if (this == obj)
        return true;
    if (!(obj instanceof ConcreteClass))
        return false;
    return getUuid().equals(((ConcreteClass) obj).getUuid());
}

Is this possible / useful? How does the Abstract class figure out the concrete class?

Referencing comments below (working code):

@Override
public boolean equals(final Object obj) {
    if (this == obj)
        return true;
    if (obj instanceof AbstractEntity && this.getUuid().equals(((AbstractEntity)obj).getUuid()))
        return true;
    return false;
}

Answer 1

You don't. All you really care about here is

obj instanceof AbstractEntity && this.getUuid().equals(((AbstractEntity)obj).getUuid())

and maybe

this.getClass() == obj.getClass()