java的分数类

概述

分数类在算法中非常重要, 而在java中不那么重要,java基础类库提供 了biginteger了,提供类似方式,

package 组合数学;

public class Fraction {

	private long Numerator; // 分子
	private long Denominator; // 分母

	public Fraction(long numerator, long denominator) {
		this.Numerator = numerator;
		if (denominator == 0) {
			throw new ArithmeticException("分母不能为零");
		} else {
			this.Denominator = denominator;
		}
		change();
	}

	public Fraction() {
		this(0, 1);
	}

	public long getNumerator() {
		return Numerator;
	}

	public void setNumerator(long numerator) {
		Numerator = numerator;
	}

	public long getDenominator() {
		return Denominator;
	}

	public void setDenominator(long denominator) {
		Denominator = denominator;
	}

	private Fraction change() {
		long gcd = this.gcd(this.Numerator, this.Denominator);
		this.Numerator /= gcd;
		this.Denominator /= gcd;
		return this;
	}

	/**
	 * 最大公因数
	 * 
	 * @param a
	 * @param b
	 * @return
	 */
	private long gcd(long a, long b) {
		long mod = a % b;
		if (mod == 0) {
			return b;
		} else {
			return gcd(b, mod);
		}
	}

	/**
	 * 四则运算
	 * @return
	 */
	public Fraction add(Fraction second) {
		return new Fraction(this.Numerator * second.Denominator + second.Numerator * this.Denominator,
				this.Denominator * second.Denominator);
	}

	public Fraction sub(Fraction second) {
		return new Fraction(this.Numerator * second.Denominator - second.Numerator * this.Denominator,
				this.Denominator * second.Denominator);
	}

	public Fraction multiply(Fraction second) {
		return new Fraction(this.Numerator*second.Numerator,
				this.Denominator * second.Denominator);
	}

	public Fraction devide(Fraction second) {
		return new Fraction(this.Numerator*second.Denominator,
				this.Denominator * second.Numerator);
	}

	@Override
	public String toString() {
		return String.format("{%d/%d}", this.Numerator, this.Denominator);
	}
	public static void main(String[] args) {
		Fraction a = new Fraction(7, 32);
		Fraction b = new Fraction(13, 32);
		System.out.println(a.add(b));
	}
}