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copied!<blockquote> <p>I will need to order them from smallest to largest, so eventually I will need to represent them as a double also</p> </blockquote> <p>Not strictly necessary. (In fact if you want to handle equality correctly, don't rely on double to work properly.) If b*d is positive, a/b < c/d if ad < bc. If there are negative integers involved, that can be handled appropriately...</p> <p>I might rewrite as:</p> <pre><code>public int compareTo(Fraction frac) { // we are comparing this=a/b with frac=c/d // by multiplying both sides by bd. // If bd is positive, then a/b < c/d <=> ad < bc. // If bd is negative, then a/b < c/d <=> ad > bc. // If bd is 0, then you've got other problems (either b=0 or d=0) int d = frac.getDenominator(); long ad = (long)this.numerator * d; long bc = (long)this.denominator * frac.getNumerator(); long diff = ((long)d*this.denominator > 0) ? (ad-bc) : (bc-ad); return (diff > 0 ? 1 : (diff < 0 ? -1 : 0)); } </code></pre> <p>The use of <code>long</code> here is to ensure there's not an overflow if you multiply two large <code>int</code>s. handle If you can guarantee that the denominator is always nonnegative (if it's negative, just negate both numerator and denominator), then you can get rid of having to check whether b*d is positive and save a few steps. I'm not sure what behavior you're looking for with zero denominator.</p> <p>Not sure how performance compares to using doubles to compare. (that is, if you care about performance that much) Here's a test method I used to check. (Appears to work properly.)</p> <pre><code>public static void main(String[] args) { int a = Integer.parseInt(args[0]); int b = Integer.parseInt(args[1]); int c = Integer.parseInt(args[2]); int d = Integer.parseInt(args[3]); Fraction f1 = new Fraction(a,b); Fraction f2 = new Fraction(c,d); int rel = f1.compareTo(f2); String relstr = "<=>"; System.out.println(a+"/"+b+" "+relstr.charAt(rel+1)+" "+c+"/"+d); } </code></pre> <p>(p.s. you might consider restructuring to implement <code>Comparable</code> or <code>Comparator</code> for your class.)</p>

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