Created
December 18, 2018 10:06
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| public class Stack<E> { | |
| private E[] elements; | |
| private int size = 0; | |
| private static final int DEFAULT_INITIAL_CAPACITY = 16; | |
| public Stack() { | |
| elements = (E[]) new Object[DEFAULT_INITIAL_CAPACITY]; | |
| } | |
| public void push(E e) { | |
| ensureCapacity(); | |
| elements[size++] = e; | |
| } | |
| public E pop() { | |
| if (size == 0) { | |
| throw new EmptyStackException(); | |
| } | |
| E result = elements[--size]; | |
| elements[size] = null; // Eliminate obsolete reference | |
| return result; | |
| } | |
| public boolean isEmpty() { | |
| return size == 0; | |
| } | |
| private void ensureCapacity() { | |
| if (elements.length == size) elements = Arrays.copyOf(elements, 2 * size + 1); | |
| } | |
| public void pushAll(Iterable<? extends E> src) { | |
| for (E e : src) { | |
| push(e); | |
| } | |
| } | |
| public void popAll(Collection<? super E> dst) { | |
| while (!isEmpty()) { | |
| dst.add(pop()); | |
| } | |
| } | |
| } | |
| interface ServiceError {} | |
| class AnotherValidationError implements ServiceError { | |
| String name; | |
| public AnotherValidationError(String name) { | |
| this.name = name; | |
| } | |
| } | |
| class ValidationError extends AnotherValidationError { | |
| String name; | |
| public ValidationError(String name) { | |
| super(name); | |
| } | |
| } | |
| // Works | |
| public void test1() { | |
| Stack<Integer> numberStack = new Stack<Integer>(); | |
| Collection<Number> objects = Arrays.asList(1, 2); | |
| numberStack.popAll(objects); | |
| } | |
| // Works | |
| public void test2() { | |
| Stack<ValidationError> stack = new Stack<ValidationError>(); | |
| Collection<ServiceError> objects = | |
| Arrays.asList(new ValidationError("A"), new ValidationError("B")); | |
| stack.popAll(objects); | |
| } |
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