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@jordancodurance
Created January 3, 2023 11:37
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Special case null stack solution for https://www.codurance.com/katalyst/stack
interface Stack {
static Stack create(int size) {
if (size < 0) throw new IllegalStackSizeException();
if (size == 0) return new NullStack();
return new BoundedStack(size);
}
void push(int element);
boolean isEmpty();
// Other operations...
}
class NullStack implements Stack {
@Override public void push(int element) {
throw new StackOverFlowException(); // 0 stack always overflows
}
@Override public boolean isEmpty() {
return true; // 0 stack is always empty
}
}
class BoundedStack implements Stack {
@Override public void push(int element) {
// push code
}
@Override public boolean isEmpty() {
// empty check code
}
}
@jordancodurance
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For the special case of a null stack, if you are using a language which supports polymorphism, consider creating a base abstract Stack, a BoundedStack with your current implementation, and a NullStack with only the code required for the 0 case. Then provide a way to construct either derivate of the stack based on the size provided.

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