Fraction Class - Google

http://www.1point3acres.com/bbs/thread-142376-1-1.html

设计一个fraction number 的class，要求实现equals和String toDecimal()。

toDecimal是leetcode原题，equals的话注意先得到gcd，然后除了之后再比较。还有分子分母是否为0，符号不一样等等都需要考虑。细节挺多的。

Also check leetcode 166: Fraction to Recurring Decimal

https://github.com/openmrs/openmrs-module-reporting/blob/master/api/src/main/java/org/openmrs/module/reporting/common/Fraction.java

	public class Fraction extends Number implements Comparable<Fraction>, Serializable {
	public static final long serialVersionUID = 1L;
	private final int numerator;
	private final int denominator;
	public Fraction(int numerator, int denominator) {
	this.numerator = numerator;
	this.denominator = denominator;
	}
	/**
	* @should return the greatest common divisor between 2 numbers
	*/
	public static int gcd(int n1, int n2) {
	if (n2 == 0) { return n1; }
	return gcd(n2, n1 % n2);
	}
	/**
	* @should return a new fraction reduced to lowest form
	*/
	public Fraction reduce() {
	int gcd = gcd(numerator, denominator);
	return new Fraction((int)numerator/gcd, (int)denominator/gcd);
	}
	/**
	* @param decimalPlaces the number of decimal points to include
	* @return this Fraction formatted as a percentage
	* @should return a percentage to the correct precision
	*/
	public String toPercentString(int decimalPlaces) {
	if (denominator == 0) { return "N/A"; }
	NumberFormat nf = NumberFormat.getPercentInstance();
	nf.setMaximumFractionDigits(decimalPlaces);
	return nf.format(doubleValue());
	}
	public int compareTo(Fraction that) {
	long n1 = this.numerator * that.denominator;
	long n2 = this.denominator * that.numerator;
	return ((n1 < n2) ? -1 : (n1 > n2 ? 1 : 0));
	}
	@Override
	public boolean equals(Object that) {
	if (this == that) { return true; }
	if (that != null && that instanceof Fraction) {
	return this.compareTo((Fraction)that) == 0;
	}
	return false;
	}
	@Override
	public int hashCode() {
	Fraction f = this.reduce();
	return 31 * (31 * 7 + f.getNumerator()) + f.getDenominator();
	}
	@Override
	public String toString() {
	return toPercentString(1) + " (" + numerator + " / " + denominator + ")";
	}
	}