Question

我是一名新手程序员。我正在尝试创建一个接受String的类，返回一个有理数，我打算用这个类进行基本的数学计算（+ - * /）。我将我的字段设置为public并添加了一个接受字符串的构造函数，然后测试一个数字是否为十进制数，如果是十进制则将其转换为rational，如果不是则将其转换为相同。但是，当我尝试编译时，我收到此错误：“类，接口或枚举预期”我检查我的{}并且它们似乎都已到位..这是我的代码

import java.lang.*; 
public class RationalNumbers{

    double numarator; 
    double denominator; 

    public RationalNumbers (String(val)){
        numerator = Integer.parseInt(val); 
        for (int i = 1; i< val.length(); i++){
            if(Val.charAt(i) == '.'){
                numerator = Math.round((numerator * Math.pow(10,(numeratorAsString.length() - (i+ 1))))); 
                denominator =  Math.pow(10,(numeratorAsString.length() - (i+ 1)));

            }else {
                numerator = numarator * 1;
                denominator = 1; 
            }
        } 
    }
    public String toString(){
        return "(" + numarator + " " + denominator + ")";
    }
}

Answer 1

将public RationalNumbers (String(val)){更改为

public RationalNumbers (String val){

Answer 2

/**
 * extends the functionality of the Date() object to include a function called addDays that adds days to
 * a javascript date based on an integer
 * @param days
 * @returns {Date}
 */
Date.prototype.addDays = function(days){

  var dat = new Date(this.valueOf());
  dat.setDate(dat.getDate() + days);
  return dat;
};

应该声明为

public RationalNumbers (String(val)){

Answer 3

String(val)请勿在{{1}}中包装变量名称，只需说()

在构造函数中使用循环 - java

3 个答案: