ArrayStack

ArrayStack

public class ArrayStack implements Stack {
    private Object[] array;
    private int size;
    private static final double koeff = 1.5d;

    public ArrayStack() {
        int initialCapacity = 2;
        array = new Object[initialCapacity];
    }

    private boolean isFull(){
        return size == array.length;
    }

    private void increaseArray(){
        Object[] newArray = new Object[(int) (size * koeff)];
        System.arraycopy(array, 0, newArray,0, size);
        array = newArray;
    }

    @Override
    public void push(Object value) {
        // TODO: check if array is full, create new, and copy values from old one
        if (isFull()){
            increaseArray();
        }
        array[size] = value;
        size++;
    }

    @Override
    public Object pop() {
        if(size==0){
            return null;
        }
        Object result = array[size - 1];
        size--;
        return result;
    }

    @Override
    public Object peek() {
        if(size==0){
            return null;
        }
        Object result = array[size - 1];
        return result;
    }

    @Override
    public int size() {
        return size;
    }

    @Override
    public boolean remove(Object value) {
        boolean result = false;

        int index = -1;
        for (int i = 0; i < size; i++) {
            if(array[i].equals(value)){
                index = i;
                break;
            }
        }
        if(index != -1){
            Object[] newArray = new Object[size-1];
            System.arraycopy(array, 0, newArray,0, index);
            System.arraycopy(array, index+1, newArray, index, size - index - 1);
            array = newArray;

            size --;
            result = true;
        }

        return result;
    }

    @Override
    public boolean contains(Object value) {
        boolean result = false;
        for (Object o : array) {
            if(o.equals(value)){
                result = true;
                break;
            }
        }

        return result;
    }
}