public boolean equals(Object obj) {
        if (obj == this) {
            return true;
        }
        if (!(obj instanceof XYInterval)) {
            return false;
        }
        XYInterval that = (XYInterval) obj;
        if (this.xLow != that.xLow) {
            return false;
        }
        if (this.xHigh != that.xHigh) {
            return false;
        }
        if (this.y != that.y) {
            return false;
        }
        if (this.yLow != that.yLow) {
            return false;
        }
        if (this.yHigh != that.yHigh) {
            return false;
        }
        return true;