An array of objects as well as their subclasses in Java

Question

I am trying to figure out how to define an array of a certain type of objects that will include the subclasses as well. This is what I have :

Property[] list = new Property[100];

I believe this will define an array of 100 properties, but is it possible for this array to include SubProperty as well. SupProperty is an extension of the Property class.

Thanks very much.

It can include SubProperty as well, but while retreiving, you'll have to cast it as SubProperty sub = (SubProperty) list[10]. Assuming, list[10] is an instance of SubProperty and not Property — Rahul Bobhate
– Rahul Bobhate, Commented May 31, 2013 at 7:01
Read - docs.oracle.com/javase/tutorial/java/concepts/inheritance.html — Sachin Gorade
– Sachin Gorade, Commented May 31, 2013 at 7:08

Devesh Chaubey · Accepted Answer · 2013-05-31 07:03:33Z

2

Yes it is possible for the array to include the SubProperty as well. Please find the code below -

class SubProperty extends Properties{
}

and

Properties[] obj = new Properties[100];
obj[1] = new SubProperty();

you can get back your Object, like -

for(Properties prop: obj){
    if(prop instanceof SubProperty){
        SubProperty subProp = (SubProperty)prop;
        System.out.println(subProp);
    }
}

answered May 31, 2013 at 7:03

Devesh Chaubey

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Javier Diaz · Accepted Answer · 2013-05-31 07:03:25Z

1

If you have

Animal[] list = new Animal[100]

Would you be able to add a Dog to that array?, If a Dog is an animal, you will be able to do Animal dog = new Dog(); That's what inheritance is, if you want to know more about it go here

answered May 31, 2013 at 7:03

Javier Diaz

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Isaac Moore · Accepted Answer · 2013-05-31 07:02:44Z

0

Yes, it is. A SubProperty object is a Property object. You can always swap a subclass for its parent.

answered May 31, 2013 at 7:02

Isaac Moore

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Evgeniy Dorofeev · Accepted Answer · 2013-05-31 07:05:22Z

0

You can use a subclass wherever its superclass can be used. This is OOP substitution principle. It also applies in this situation.

answered May 31, 2013 at 7:05

Evgeniy Dorofeev

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