需要帮助修复这段代码

Question

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

public Number(int numerator, int denominator) { 
    this.numerator = numerator; 
    this.denominator = denominator; 
} 

public Number() { 
    this.numerator = 0; 
    this.denominator = 1; 
} 

public int getDenominator() { 
    return denominator; 
} 

public int getNumerator() { 
    return numerator; 
} 

public String toString() { 
    if (numerator == 0) { 
     return "0"; 
    } else if (denominator == 1) { 
     return denominator + ""; 
    } 
    return numerator + "/" + denominator; 
} 

public Number subtract(Number other) { 
    numerator = (this.getNumerator() * other.getDenominator()) - (other.getNumerator() * this.getDenominator()); 
    denominator = this.getDenominator() * other.getDenominator(); 

    return this; 
} 

//// 
public class test { 
public static void main(String[] args) { 
    Number n1 = new Number(1, 2); 
    Number n2 = new Number(3, 5); 
    Number n4 = new Number(7, 40); 
    Number test = n2.subtract(n1); 
    System.out.println(test); 
    Number test2 = n4.subtract(n1); 
    System.out.println(test2); 
    Number test3 = n1.subtract(n4); 
    System.out.println(test3); 
    Number test4 = n2.subtract(n1); 
    System.out.println(test4); 

} 
} 

我遇到了number subtract（）方法的问题。当我从客户端调用它的时候，它在某些时候会有效，但是在几次连续的调用之后，我得到了意想不到的输出。前两个电话工作正常，然后我开始得到的结果是远离。我知道我在减法（）方法中丢失了一些东西，只是不确定它是什么。

任何帮助，将不胜感激。

Answer 1

如果在对象上使用减法，则将最后一行更改为return this。顺便说一句，你的比例类型的减法是错误的。

Answer 2

我最终解决了自己的问题，但我很感谢大家的帮助。我知道这可能不是解决这个问题的最有效的方法，但我只是第一年的CS学生。如果任何人有任何建议来清除这个代码，我很乐意听到它。谢谢！

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

public Number(int numerator, int denominator) { 
    reduce(numerator, denominator); 
} 

public Number() { 
    this.numerator = 0; 
    this.denominator = 1; 
} 

public int getDenominator() { 
    return denominator; 
} 

public int getNumerator() { 
    return numerator; 
} 

public String toString() { 
    if (numerator == 0) { 
     return "0"; 
    } else if (denominator == 1) { 
     return numerator + ""; 
    } 
    return numerator + "/" + denominator; 
} 

public Number add(RationalNumber other) { 
    int numerator1 = (numerator * other.getDenominator()) + (other.getNumerator() * denominator); 
    int denominator1 = denominator * other.getDenominator(); 

    return new Number(numerator1, denominator1); 
} 

public Number subtract(RationalNumber other) { 
    int numerator1 = (numerator * other.getDenominator()) - (other.getNumerator() * denominator); 
    int denominator1 = denominator * other.getDenominator(); 

    return new Number(numerator1, denominator1); 
} 

public Number multiply(RationalNumber other) { 
    int numerator1 = numerator * other.getNumerator(); 
    int denominator1 = denominator * other.getDenominator(); 

    return new Number(numerator1, denominator1); 
} 

public Number divide(RationalNumber other) { 
    int numerator1 = numerator * other.getDenominator(); 
    int denominator1 = denominator * other.getNumerator(); 

    return new Number(numerator1, denominator1); 
} 

private void reduce(int numerator, int denominator) { 
    int factor = 1; 
    int temp = 0; 
    if (Math.abs(numerator) > Math.abs(denominator)) { 
     temp = Math.abs(numerator); 
    } else if (Math.abs(denominator) > Math.abs(numerator)) { 
     temp = Math.abs(denominator); 
    } 
    for (int i = temp; i > 0; i --) { 
     if ((numerator %i == 0) && (denominator %i == 0)) { 
      factor = i; 
      i = 0; 
     } 
    } 
    numerator = numerator/factor; 
    denominator = denominator/factor; 
    rightForm(numerator, denominator); 
} 
private void rightForm(int numerator, int denominator) { 
    if (numerator > 0 && denominator < 0) { 
     this.numerator = numerator - numerator - numerator; 
     this.denominator = Math.abs(denominator); 
    } else if (numerator < 0 && denominator < 0) { 
     this.numerator = Math.abs(numerator); 
     this.denominator = Math.abs(denominator); 
    } else { 
     this.numerator = numerator; 
     this.denominator = denominator; 
    } 
} 

}