public Object[] subarray_as_Object(int start, int end){
        if(end>=this.length)throw new IllegalArgumentException("end, " + end + ", is greater than the highest index, " + (this.length-1));
        Object[] arrayo= new Object[end-start+1];
        for(int i=start; i<=end; i++)arrayo[i-start] = this.array.get(i);
        return arrayo;
    }