How to make an ArrayList immutable in Java without API?

Asked Mar 24 '18 at 04:55

Active Mar 24 '18 at 04:55

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To make the list unmodifiable in a derived class and to the external world, I understand that it must be declared private and final. How would it be modified to make it immutable even within the same class without using the unmodifiableList method? I must clarify that this is for a theoretical scenario asked during an interview.

I was told that it has something to do with not allowing changes to hashCode(), but can someone please give me a concrete solution? By extension, I also want to know how to make any (custom) object immutable.

asked Mar 24 '18 at 04:55

Dharini

there is a nice discussion here, https://stackoverflow.com/questions/6305752/how-to-create-immutable-objects-in-java – parlad Mar 24 '18 at 04:59
Just create `MyList` that does not provide methods for modification and `MyList` is-a `List`. – Aniket Sahrawat Mar 24 '18 at 04:59
You could make your own `List` class in which the `add`, `addAll` and `remove` methods throw an `UnsupportedOperationException`. – Dawood ibn Kareem Mar 24 '18 at 05:02
Making `List` immutable would make the code bulky. I'm better off creating my own linked list. – Dharini Mar 24 '18 at 16:29

How to make an ArrayList immutable in Java without API?

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