java - 麻烦简化java中的分数

Question

我正在尝试编写一个程序，它接受两个分数，然后对它们进行加、减、乘和除，然后在必要时将它们放入最简单的形式。

我遇到的唯一问题是分数没有简化，我不确定为什么。

例如，现在当我运行分数 3/4 和 1/4 时，它会给出以下答案:加法:4/4减法:2/4乘法:3/16划分:12/4

我希望加法为 1/1，减法为 1/2，除法为 3/1。下面是我的代码。

import java.util.*;
public class RationalNumber
{
private int numerator;
private int denominator;//instance variables
//constructor
public RationalNumber()
{
    numerator = 0;
    denominator = 1;
}

public RationalNumber(int num, int den)
{
    setNumerator(num);
    setDenominator(den);
    int gcf= greatestCommonFactor(num, den);

    num = num/gcf;
    den = den/gcf;
    /*num = num/(greatestCommonFactor(num, den));
    den = den/(greatestCommonFactor(num, den));*/
}

//getters
public int getDenominator()
{
    return denominator;
}

public int getNumerator()
{
    return numerator;
}

//setters
public void setNumerator(int num)
{
    numerator = num;
}

public void setDenominator(int den)
{
    denominator = den;
}

//adds the rational numbers
public RationalNumber add(RationalNumber two)
{
    RationalNumber add = new RationalNumber();
    if(getDenominator() == two.getDenominator())
    {
        int newNum = numerator + two.numerator;//simply adds the numerators if the denominators are the same
        /*newNum = newNum/(greatestCommonFactor(newNum, denominator));
        int newDen = denominator/(greatestCommonFactor(newNum, denominator));//simplification*/
        return new RationalNumber(newNum, denominator);
    }
    else
    {
        int newDen = getDenominator() * two.getDenominator();
        int leftNum = getNumerator() * two.getDenominator();
        int rightNum = getDenominator() * two.getNumerator();//cross multiplication

        /*int newNum = (leftNum + rightNum)/(greatestCommonFactor((leftNum + rightNum), getDenominator()));//simplification
        newDen = denominator/(greatestCommonFactor(newNum, getDenominator()));*/

        return new RationalNumber(leftNum + rightNum, newDen);
    }
}

//subtracts the rational numbers, same math as the add method but with subtraction signs
public RationalNumber sub(RationalNumber two)
{
    RationalNumber sub = new RationalNumber();

    if(this.getDenominator() == two.getDenominator())
    {
        int newNum = this.numerator - two.numerator;
        return new RationalNumber(newNum, this.getDenominator());
    }
    else
    {
        int newDen = this.getDenominator() * two.getDenominator();
        int leftNum = this.getNumerator() * two.getDenominator();
        int rightNum = this.getDenominator() * two.getNumerator();
        return new RationalNumber(leftNum - rightNum, newDen);
    }

}

//multiplies the two rational numbers
public RationalNumber mult(RationalNumber two)
{
    RationalNumber mult = new RationalNumber();
    mult.denominator = denominator * two.denominator;
    mult.numerator = numerator * two.numerator;

    return mult;
}

//divides the rational numbers
public RationalNumber div(RationalNumber two)
{
    RationalNumber div = new RationalNumber();
    div.denominator = denominator * (two.numerator);
    div.numerator = numerator * two.denominator;//multiply by reciprocal in order to divide

    return div;
}

//returns the reciprocal of a rational number
public RationalNumber reciprocal(RationalNumber two)
{
    RationalNumber reciprocal = new RationalNumber();
    reciprocal.denominator = numerator;
    reciprocal.numerator = denominator;
    return reciprocal;
}

//returns the inverse of a rational number
public RationalNumber inverse(RationalNumber two)
{
    RationalNumber inverse = new RationalNumber();
    inverse.numerator = (numerator*-1);
    return inverse;
}

//finds the greatest common factor, used in simplifying
public int greatestCommonFactor(int num, int den)
{
    for(int i = (Math.max(num,den)/2)+1; i > 0; i--)
    {
        if((num/i) == Math.round(num/i) && (den/i) == Math.round(den/i))
            return i;//loop finds the GCF by finding if numerator & denominator divided by i is an even number
    }
    return 1;
}

public String toString()
{
    return numerator + "/" + denominator;//prints the numerator and denominator as a string
}
}

Answer 1

您的 greatestCommonFactor 函数给我错误的结果。尝试用这个测试(这是使用 Euclid 的方法):

//finds the greatest common factor, used in simplifying
public int greatestCommonFactor(int num, int den)
{
    if(den == 0){
        return num;
    }
    return greatestCommonFactor(den, num % den);
}

此外，您不要将numerator 或denominator 设置为它们的简化形式:

public RationalNumber(int num, int den)
{
    //setNumerator(num);
    //setDenominator(den);
    int gcf= greatestCommonFactor(num, den);
    setNumerator(num/gcf);
    setDenominator(den/gcf);
}