I want to flatten nested arrays like:
[[[1],2],[3]],4] -> [1,2,3,4]
manually in java I can\'t find a clue ! :S
I have tried a
It could be flattened by iterative approach.
static class ArrayHolder implements Iterator { private final Object[] elements; private int index = -1; public ArrayHolder(final Object[] elements) { this.elements = elements; } @Override public boolean hasNext() { return Objects.nonNull(elements) && ++index < elements.length; } @Override public Object next() { if (Objects.isNull(elements) || (index == -1 || index > elements.length)) throw new NoSuchElementException(); return elements[index]; } } private static boolean hasNext(ArrayHolder current) { return Objects.nonNull(current) && current.hasNext(); } private void flat(Object[] elements, List flattened) { Deque stack = new LinkedList<>(); stack.push(new ArrayHolder(elements)); ArrayHolder current = null; while (hasNext(current) || (!stack.isEmpty() && hasNext(current = stack.pop()))) { Object element = current.next(); if (Objects.nonNull(element) && element.getClass().isArray()) { Object[] e = (Object[]) element; stack.push(current); stack.push(new ArrayHolder(e)); current = null; } else { flattened.add(element); } } }
You can find the full source here You can use recursion to solve this problem.
private void flat(Object[] elements, List flattened) { for (Object element : elements) { if (Objects.nonNull(element) && element.getClass().isArray()) { flat((Object[])element, flattened); } else { flattened.add(element); } } }
Here is the link for recursion.
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