整数/双重交互的意外结果-除法运算后返回零

Question

我对“ documentLength”变量有疑问。 当我将参数输入到方法中时，它是93。但是由于某种原因，它会更改。 输入参数也是一个int变量。

我将这个类称为Word，然后将其从main中的checkWord类中的职业中的方法称为：

double occupation = word.get(1).occupationOfDocument(documentLength); // line 83 in run-time below

职业文档

public double occupationOfDocument(int documentLength){
    int length = getLength(); //equals 8 when I run the program
    int occurances = getOccurances(); //equals 3 when I run the program
    System.out.println(documentLength); //Prints 93 as expected

    double occupation = ((length * occurances)/documentLength)*100; //equals 0 somehow (probably division by)

    return occupation; //expected around 25.8
}

该方法返回“ 0”，但是如果我将代码更改为此，

private int documentLength = 0;
public double occupationOfDocument(int documentLength){
    int length = getLength(); //equals 8 when I run the program
    int occurances = getOccurances(); //equals 3 when I run the program
    documentLength = this.documentLength;
    System.out.println(documentLength); //Prints 0 somehow

    double occupation = ((length * occurances)/documentLength)*100; //equals 0 somehow (probably divisjon by 0)

    return occupation; //expected around 25.8
}

我收到以下运行时错误：

 Exception in thread "main" java.lang.ArithmeticException: / by zero at Word.occupationOfDocument(Word.java:44) at checkWord.main(checkWord.java:83) 

Word.java:44这是数学行，我在其中声明和初始化职业

我知道它表示我被0除。我只是不知道它是如何发生的。

如果我输入数字而不是变量“ documentLength”，则脚本将按预期运行

感谢您的帮助;）

IT学生需要帮助

Answer 1

public double occupationOfDocument(int documentLength){
  int length = getLength(); //equals 8 when I run the program
  int occurances = getOccurances(); //equals 3 when I run the program
  System.out.println(documentLength); //Prints 93 as expected

  double occupation = ((length * occurances)/documentLength)*100; //equals 0 somehow (probably division by)

  return occupation; //expected around 25.8

}

在这里，您将8乘以3并得到24，然后将整数除以93-得到0。

如果您修改该行

double occupation = ((double) (length * occurances)/documentLength)*100; 

将会产生适当的结果。 了解有关类型转换和类型扩展以获得更多上下文的更多信息。

Answer 2

您在第一种情况下进行整数除法，这意味着例如4/3 = 1 ，在您的情况下为24/93 = 0如果要使其为双24/93 = 0则需要在int值上添加24/93 = 0 ：

double occupation = (((double)(length * occurances))/((double)documentLength))*100;

应该是安全的。 至于第二个错误，您明确告诉程序

documentLength = this.documentLength; //this.documentLength = 0 as you defined above

double occupation = ((length * occurances)/documentLength)*100;