Question

我对＆＃34; documentLength＆＃34;有一个问题。变量。当我将参数输入到方法中时，它是93.但由于某种原因它会改变。输入参数也是一个int变量。

我调用了Word类，其中的方法就是来自类的checkWord中的OccupOfDocument，如下所示：

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

occupationOfDocument看起来像这样

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
}

此方法返回＆＃34; 0＆＃34;，但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RUN-TIME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 这是数学的一行，我宣布和初始化职业

我知道它说我要除以0.我只是不明白它是如何发生的。

如果我输入数字而不是变量＆＃34; documentLength＆＃34;，脚本会按预期执行

感谢您的帮助;）

需要帮助的IT学生

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，你将8乘以3并得到24，然后你将整数除以93 - 这就得到0。

如果您修改

行

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

将产生适当的结果。详细了解type conversion and type widening以获取更多背景信息。

Answer 2

你在第一个场景中进行整数除法，例如4/3 = 1，在你的情况下是24/93 = 0，如果你想把它作为一个double，你需要为int值添加一个强制转换：

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

应该是安全的。至于你明确告诉程序

的第二个错误

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

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

整数/双重交互的意外结果 - 在除法运算后返回零

2 个答案: