java - 窃听了我自己的 If-Else 语句

Question

所以我是一名正在学习 Java 的学生。我目前正忙于一项作业，但我一直被一些 if-else 逻辑所困。

我的作业要求我编写一个包含有理数(例如 72/14)的类文件，显示它，将其分解为最低形式(在本例中为 36/7)，将有理数显示为 double 值，最后显示最大公因数。我坚持的事实是我的代码没有筛选出这样一个事实，例如，72/13 是有理数可以变成的最小值，但我明白了，所以它不会崩溃，但反过来我将其换成 72/14 的值(value)搜索，但无法正常工作。

我的代码:

public class QTwoAssiThree
{
    private int numerator;
    private int denominator;

    public void writeOutput()
    {
        if (getGCD(numerator, denominator) >= 2)
        {
            System.out.println(toString() + " is the simplified rational number.");
            System.out.println(getValue() + " is the value of the two rational numbers as one number.");
            System.out.println((getGCD(numerator, denominator) * 2) + " is the largest common factor.");
        }
        else if (getGCD(numerator, denominator) == 1)
        {
            System.out.println(getValue() + " is the value of the two rational numbers as one number.");
            System.exit(0);
        }       
    }
    public QTwoAssiThree()
    {
        numerator = 0;
        denominator = 0;
    }
    public QTwoAssiThree(int initialNum, int initialDenom)
    {
        if (denominator % 2 == 0)
        { 
            numerator = initialNum;
            if (initialDenom > 0)
            {
                denominator = initialDenom;
                System.out.println(toString() + " is the rational number entered.");
                simplify(numerator, denominator);
            }
            else
            {
                System.out.println("Invalid value added as the denominator! Only positive integers should be used.");
                System.exit(0);
            }
        }
        else if (denominator % 2 == 1)
        {
            System.out.println(toString() + " is what was entered, and is already in its simplest form.");
        }   
    }
    private void simplify(int newNum, int newDenom)
    {
        numerator = newNum / getGCD(newNum, newDenom);
        denominator = newDenom / getGCD(newNum, newDenom);
    }
    private static int getGCD(int x, int y)
    {
        int difference = x % y;

        return difference;
    }
    private double getValue()
    {
        double doubleValue = (double)numerator / (double)denominator;

        return doubleValue;
    }
    public String toString()
    {
        String fraction = Integer.toString(numerator) + "/" + Integer.toString(denominator);

        return fraction;
    }
}

现在，请忽略我在知识渊博的 Java 程序员等级上仍然有些低的事实。我将不胜感激任何关于此的指示，因为我被卡住了并且无法真正弄清楚如何设置它。我在两个地方使用 if-else 来查看它是否有效，第一个是: public void writeOutput() 和 public QTwoAssiThree(int initialNum, int initialDenom) 构造函数。最初那里没有任何 if-else 语句，虽然代码确实有效，但不适用于非奇数整数。

public class QTwoAssiThreeDemo
{
    public static void main(String[] args)
    {
        QTwoAssiThree rationalNumbers = new QTwoAssiThree(72, 14);

        rationalNumbers.writeOutput();
    }
}

用于演示全类。

基本上我的输出应该如下所示:

    72/14 is the rational number entered.
    36/7 is the simplified rational number.
    5.142857143 is the value of the two rational numbers as one number.
    2 is the largest common factor.

和

    72/13 is what was entered,  and is already in its simplest form.
    5.538461538 is the value of the two rational numbers as one number.

代码未经优化，看起来很丑，我知道，但如果有任何帮助，我们将不胜感激，在提交作业之前，我会仔细检查一下，让它看起来更漂亮一些。

Answer 1

需要修改的代码(IMO):

1. 构造函数只能用于初始化对象
2. 已更改 GCD引用链接后的功能
3. 您可以在构造函数中添加简化函数(因为它会重新初始化值)
4. 使用 try 和 catch block 来检查它们是否是有效输入，否则抛出 Exceptions

修改后的代码:

public class QTwoAssiThree {
    private int numerator;
    private int denominator;

    public void writeOutput() {

        System.out.println(toString() + " is the rational number entered.");
        if (simplify(numerator, denominator)>1)
            System.out.println(toString()+ " is the simplified rational number.");
        else
            System.out.println(toString()+ " is what was entered, and is already in its simplest form.");
        System.out .println(getValue() +" is the value of the two rational numbers as one number.");
    }

    public QTwoAssiThree() {
        numerator = 0;
        denominator = 0;
    }

    public QTwoAssiThree(int initialNum, int initialDenom) {

        numerator = initialNum;
        denominator = initialDenom;
        if (initialDenom <= 0) {
            System.out
                    .println("Invalid value added as the denominator! Only positive integers should be used.");
            System.exit(0);
        }
    }

    private int simplify(int newNum, int newDenom) {
        int gcd = getGCD(newNum, newDenom);
        numerator = newNum / gcd;
        denominator = newDenom / gcd;
        return gcd;
    }

    private static int getGCD(int x, int y) {

        if (y == 0) {
            return x;
        }
        return getGCD(y, x % y);
    }

    private double getValue() {
        double doubleValue = (double) numerator / (double) denominator;

        return doubleValue;
    }

    public String toString() {
        String fraction = Integer.toString(numerator) + "/"
                + Integer.toString(denominator);

        return fraction;
    }
}