分数 class 分数 Driver 疑难解答

Question

我在第一学期使用 Java 编程，我们刚刚开始接触 OOP，我运行遇到了我的代码的一个小问题（不足为奇）。需要大师们的帮助才能弄清楚缺少什么，我知道我已经很接近答案了。基本上我得到了一个 driver 分数 class ，我需要自己写 class 。 driver 中的所有内容都必须保持原样。

这是 driver：

import java.util.Scanner;

public class FractionDemo
{

public static void main(String[] args)
{
Scanner stdIn = new Scanner(System.in);
Fraction c, d, x;       // Fraction objects

System.out.println("Enter numerator; then denominator.");
c = new Fraction(stdIn.nextInt(), stdIn.nextInt());
c.print();

System.out.println("Enter numerator; then denominator.");
d = new Fraction(stdIn.nextInt(), stdIn.nextInt());
d.print();

x = new Fraction();     // create a fraction for number 0


System.out.println("Sum:");
x.add(c).add(d);
x.print();

x.printAsDouble();

x = new Fraction(1, 1); // create a fraction for number 1

System.out.println("Product:");
x.multiply(c).multiply(d);
x.print();

x.printAsDouble();

System.out.println("Enter numerator; then denominator.");
x = new Fraction(stdIn.nextInt(), stdIn.nextInt());
x.printAsDouble();

}
} // end main

这是我得到的分数 class。

public class Fraction
{
private int numerator;  // numerator of the fraction
private int denominator;   // denominator of the fraction

//**************************************************

public void Fraction()
{
numerator = 0;
denominator = 1;
}
// default constructor

public void Fraction(int n, int d)
{
numerator = n;
denominator = d;
}
//two parameter constructor

public void print()
{
System.out.println(numerator + "/" + denominator);
} //print fraction as n/d

public void printAsDouble()
{
System.out.printf("%f", numerator/denominator);
} //print fraction as double

public Fraction add(Fraction other)
{
//add
// calling object = calling obj + parameter
int n = this.numerator * other.denominator +
this.denominator * other.numerator;
int d = this.denominator * other.denominator;
this.numerator = n;
this.denominator = d;
return this;
}  
//multiply
public Fraction multiply(Fraction other)
{
int n = this.numerator * other.numerator;
int d = this.denominator * other.denominator;
this.numerator = n;
this.denominator = d;
return this;
}

} // end Fraction class

这是我收到的错误消息：

FractionDemo.java:19: error: constructor Fraction in class Fraction cannot be applied to given types;
    c = new Fraction(stdIn.nextInt(), stdIn.nextInt());
        ^
  required: no arguments
  found: int,int
  reason: actual and formal argument lists differ in length

FractionDemo.java:23: error: constructor Fraction in class Fraction cannot be applied to given types;
    d = new Fraction(stdIn.nextInt(), stdIn.nextInt());
        ^
  required: no arguments
  found: int,int
  reason: actual and formal argument lists differ in length
FractionDemo.java:35: error: constructor Fraction in class Fraction cannot be applied to given types;
    x = new Fraction(1, 1); // create a fraction for number 1
        ^
  required: no arguments
  found: int,int
  reason: actual and formal argument lists differ in length

FractionDemo.java:44: error: constructor Fraction in class Fraction cannot be applied to given types;
    x = new Fraction(stdIn.nextInt(), stdIn.nextInt());
        ^
  required: no arguments
  found: int,int
  reason: actual and formal argument lists differ in length
4 errors

Tool completed with exit code 1

Answer 1

你这样声明你的构造函数：

public void Fraction()
public void Fraction(int n, int d)

构造函数没有 return 类型。声明它们：

public Fraction()
public Fraction(int n, int d)

分数 class 分数 Driver 疑难解答

Fraction class troubleshooting for Fraction Driver

java

oop

driver