Java how to add child class to an array

Question

at the moment, I am wondering if there is a way to add a child class object to a parent class array.

I have code that follows the generic line of:

    public abstract class Parent {  
        ...
    }

    public class Child extends Parent {
        ...
    }

And I have an array that follows along the lines of:

Parent[] array = new Parent[number];

I want to be able to add my child objects to this array like:

array[0] = new Child();

However whenever I do this, I get an error message saying that they are incompatible types. I know this can be achieved in ArrayList but I want to see if it is possible in the format above. Is there a way to achieve this without ArrayList?

This doesn't compile Parent[] array = new Parent[]; I suspect your code is different which is the reason it doesn't compile. — Peter Lawrey
– Peter Lawrey, Commented Dec 18, 2013 at 11:18
Ahh okay, I come from a C# background and quite new to Java. Any help will be appreciated. — Hayden
– Hayden, Commented Dec 18, 2013 at 11:19
I edited the number in the array if that is what you are talking about. — Hayden
– Hayden, Commented Dec 18, 2013 at 11:20

Duncan Jones · Accepted Answer · 2013-12-18 11:20:48Z

4

The following code compiles without error:

public abstract class Parent {

  private static class Child extends Parent {}

  public static void main(String[] args) throws Exception {
    Parent[] array = new Parent[1];
    array[0] = new Child();
  }
}

This is very similar to the code in your question. So perhaps compare your code with mine and spot the difference?

In Java (and in most/all OO languages), this polymorphic behaviour is standard and completely correct.

answered Dec 18, 2013 at 11:20

Duncan Jones

69.7k32 gold badges204 silver badges262 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Hayden Over a year ago

I feel so foolish, I added a completely different class which is named similarly to the child class. Thank you guys for your help.

Lucas · Accepted Answer · 2013-12-18 11:23:21Z

0

How about trying this:

    enter codepublic abstract class Parent {

  private static class Child extends Parent {}

  public static void main(String[] args) throws Exception {
    Parent[] array = new Parent[1];
    Parent child = new Child();
    array[0] = child;
  }
} here

answered Dec 18, 2013 at 11:23

Lucas

3,2914 gold badges28 silver badges46 bronze badges

Comments

Eugene Kisly · Accepted Answer · 2013-12-18 11:25:27Z

0

Just put size of array when creating, everything works with it :)

Parent[] array = new Parent[5]; array[0] = new Child();

answered Dec 18, 2013 at 11:25

Eugene Kisly

13713 bronze badges

Collectives™ on Stack Overflow

Java how to add child class to an array

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related