public boolean equals(Object obj) {
        if (obj == this) {
            return true;
        }
        if (!(obj instanceof NumberAxis)) {
            return false;
        }
        if (!super.equals(obj)) {
            return false;
        }
        NumberAxis that = (NumberAxis) obj;
        if (this.autoRangeIncludesZero != that.autoRangeIncludesZero) {
            return false;
        }
        if (this.autoRangeStickyZero != that.autoRangeStickyZero) {
            return false;
        }
        if (!ObjectUtilities.equal(this.tickUnit, that.tickUnit)) {
            return false;
        }
        if (!ObjectUtilities.equal(this.numberFormatOverride,
                that.numberFormatOverride)) {
            return false;
        }
        if (!this.rangeType.equals(that.rangeType)) {
            return false;
        }
        return true;