如何制作简化分数的 Java 方法？

Question

我写了一个分数类，但在简化时遇到了麻烦。

当我制作 Fraction 对象时，一切正常，我只是觉得我的逻辑在简化方面很混乱。

（num和den分别是类中的分子和分母的私有变量）

这是我的 GCD 和 Simplify 方法：

/**
 * Returns the absolute value of the greatest common divisor of this
 * fraction's numerator and denominator. If the numerator or denominator is
 * zero, this method returns 0. This method always returns either a positive
 * integer, or zero.
 * 
 * @return Returns the greatest common denominator
 */
private int gcd() {
    int s;
    if (num > den)
        s = den;
    else
        s = num;
    for (int i = s; i > 0; i--) {
        if ((num % i == 0) && (den % i == 0))
            return i;
    }
    return -1;
}

/**
 * Changes this fraction's numerator and denominator to "lowest terms"
 * (sometimes referred to as a "common fraction"), by dividing the numerator
 * and denominator by their greatest common divisor. This includes fixing
 * the signs. For example, if a fraction is 24/-18, this method will change
 * it to -4/3. If the numerator or denominator of the fraction is zero, no
 * change is made.
 */
public void simplify() {

    if (isZero() == false) {// Making sure num or den is not zero.
        this.fixSigns(); // Fix signs first

        if (gcd() > 1) {
            this.num = num / gcd();
            this.den = num / gcd();
        }
    }
}

Answer 1

我马上看到两件事：您将num 除以gcd() 两次，分别是分子和分母。此外，一旦您更改了分子，那么对gcd() 的调用结果可能会发生变化。调用“gcd”一次，存储结果，稍后使用：

int gcd = gcd();
if (gcd > 1) {
   this.num = this.num / gcd;
   this.den = this.den / gcd;
}

此外，还有更有效的获取最大公约数的方法：Wikipedia's page。请参阅该页面上的 Euclid 算法。