i've been wondering how does the interface List in java store data. An interface is a set of methods that must be implemented by a class (please correct if i'm wrong) and thus a list can't have variables to store data.
For instance, List<Integer> list1 = new ArrayList<>(); list1.add(5);
where will the integer 5 be stored ? Does the list1 use the ArrayList's attributes to store data ? What really happens when i create an interface ? Does it create an object of a certain class to operate on it ?
Thank you
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Ousmane D.
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Ahmed Gharbi
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Read the ArrayList class – Mạnh Quyết Nguyễn May 20 '18 at 16:46
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As you already noticed, the `List` interface can not store data. But the `ArrayList` can and stores the data in an array. A `LinkedList` stores that information as linked list. But you can use both of them interchangeable when you only use the `List` interface. – Johannes Kuhn May 20 '18 at 16:48
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Interfaces need an implementation chosen. – Thorbjørn Ravn Andersen May 20 '18 at 16:54