@Override
    public boolean equals(Object obj) {
        if (obj == null) {
            return false;
        }
        if (getClass() != obj.getClass()) {
            return false;
        }
        final Volume other = (Volume) obj;
        if (this.hoogte != other.hoogte) {
            return false;
        }
        if (this.breedte != other.breedte) {
            return false;
        }
        if (this.diepte != other.diepte) {
            return false;
        }
        return this.maat == other.maat;
    }