Abstract type: Difference between revisions

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Here Node is an abstract type that is inherited from Limited_Controlled and implements a node of a [[Doubly-Linked List (element) | doubly linked list]]. It also implements the interface of a queue described above, because any node can be considered a head of the queue of linked elements. For the operation Finalize an implementation is provided to ensure that the element of a list is removed from there upon its finalization. The operation itself is inherited from the parent type Limited_Controlled and then overridden. The operations Dequeue and Enqueue of the Queue interface are also implemented.

=={{header|C++}}==

You can declare a virtual function to not have an implementation (called "pure virtual function") by the following "<code>= 0</code>" syntax after the method declaration. A class containing at least one pure virtual function (or inheriting one and not overriding it) cannot be instantiated.

<java>class Abs {

public:

virtual int method1(double value) = 0;

virtual int add(int a, int b){

return a+b;

}

};</java>

Because C++ allows multiple inheritance of classes, no distinction is made between interfaces and abstract classes.

=={{header|Java}}==