public class ResizableArray {

    private int length;

    private int[] elems;

​

    public ResizableArray(int length){

        this.length = length;

        this.elems = new int[length];

    }

​

    public int lenght(){

        return length;

    }

​

    public void add (int newValue){

​

        grow();

        elems [elems.length-1] = newValue;

    }

​

    private void grow(){

        int[] newElems = new int[elems.length+1];

        copy (elems, newElems);

        elems = newElems;

        length = length + 1;

    }

​

​

​

    public void copy (int[] from, int[] to){

        System.arraycopy(from, 0, to, 0, from.length);

    }

​

    public  void add (int index, int newValue){

        int [] newElems = new int[elems.length+1];

        System.arraycopy(elems, 0, newElems, 0, index);

        System.arraycopy(elems, index, newElems, index+1, elems.length-index);

        elems = newElems;

        elems [index] = newValue;

        length++;

    }

}

​