Java 需要帮助编译此迭代和接口程序吗
我试图编写这个java程序,让用户输入两个有理数,然后从选项菜单中请求计算某种函数a。我被困在几个地方,不知道还能做什么。我需要一些指导。它不会编译。表示构造函数Rational未定义,最后一个默认值是无效标签。这是两个类文件,驱动程序文件使用Rational文件。这两个文件都被上传并用文本分隔。需要帮助吗Java 需要帮助编译此迭代和接口程序吗,java,inheritance,interface,compiler-errors,Java,Inheritance,Interface,Compiler Errors,我试图编写这个java程序,让用户输入两个有理数,然后从选项菜单中请求计算某种函数a。我被困在几个地方,不知道还能做什么。我需要一些指导。它不会编译。表示构造函数Rational未定义,最后一个默认值是无效标签。这是两个类文件,驱动程序文件使用Rational文件。这两个文件都被上传并用文本分隔。需要帮助吗 import java.util.Scanner; import java.util.*; public class RationalDriver{ public static
import java.util.Scanner;
import java.util.*;
public class RationalDriver{
public static void main(String[] args){
int rationalNum1, rationalDen1, rationalNum2, rationalDen2;
Scanner in = new Scanner(System.in);
// first rational
System.out.println(" Input first rational number for the Numerator");
rationalNum1 = in.nextInt();
System.out.println(" Input first rational number for the Denominator");
rationalDen1 = in.nextInt();
if (rationalDen1 == 0){
System.out.println(" Cannont divide by zero ");
System.out.println(" please re enter another number ");
}
System.out.println("Rational Number #1 = ("+rationalNum1+"/"+rationalDen1+")");
//Displays 1st Rational Number
// second rational
System.out.println(" Input 2nd rational number for the 2nd Numerator");
rationalNum2 = in.nextInt();
System.out.println(" Input 2nd rational number for the 2nd Denominator");
rationalDen2 = in.nextInt();
if (rationalDen2 == 0){
System.out.println("Cannont divide by zero");
System.out.println(" please re enter another number");
}
System.out.println("Rational Number #2 = ("+rationalNum2+"/"+rationalDen2+")");
//Displays 2nd Rational Number
Rational r1 = new Rational ( rationalNum1, rationalDen1);
Rational r2 = new Rational ( rationalNum2, rationalDen2);
// System.out.println;//toString
}
public void display_menu() //menu options
{
System.out.print(" Enter the corresponding number for the desired action ");
System.out.println("1) Addition\n2) 2) Subtraction\n3) 3) Multiplication\n4) 4)Division\n5) 5) Test for Eqaulity\n6) 6) Change 1st rational number\n7) 7) Change 2nd rational number");
}
public void question()
{
System.out.println("Do you want to exit? [y/n]"); // ask user if they want to quit with yes or no option
Scanner q = new Scanner(System.in);
switch (q.nextInt())
{
case 'y' :
System.out.println ("Thank you and goodbye.");
break;
case 'n' :
InputMenu();
break;
default:
System.err.println ( "Unrecognized option" );
break;
}
}
public void InputMenu() // keys for the menu
{
Scanner in = new Scanner(System.in);
display_menu();
switch (in.nextInt())
{
case 1: //addition
System.out.println ( "1" );
System.out.println( "("+rationalNum1+"/"+rationalDen1+")"+ " + " + " ("+rationalNum2+"/"+rationalDen2+")" + "=" + r1.add(r2));
break;
case 2: //subtraction
System.out.println ( "2" );
System.out.println( "("+rationalNum1+"/"+rationalDen1+")"+ " - " + "("+rationalNum2+"/"+rationalDen2+")" + "=" + r1.subtract(r2));
break;
case 3: //mulitplication
System.out.println ( "3" );
System.out.println( "("+rationalNum1+"/"+rationalDen1+")"+ " * " + " ("+rationalNum2+"/"+rationalDen2+")" + "=" + r1.multiply(r2));
break;
case 4: //division
System.out.println ( "4" );
System.out.println( "("+rationalNum1+"/"+rationalDen1+")"+ " / " + "("+rationalNum2+"/"+rationalDen2+")" + "=" + r1.divide(r2));
break;
case 5: //compare to
System.out.println ( "5" );
question();
break;
case 6: //change the 1st Rational Number
System.out.println ( "6" );
Scanner in = new Scanner(System.in);
System.out.println(" Input first rational number for the Numerator");
rationalNum1 = in.nextInt();
System.out.println(" Input first rational number for the Denominator");
rationalDen1 = in.nextInt();
if (rationalDen1 == 0){
System.out.println(" Cannont divide by zero");
System.out.println(" please re enter another number");
}
break;
case 7: //change the 2nd Rational Number
System.out.println ( "7" );
System.out.println(" Input 2nd rational number for the 2nd Numerator");
rationalNum2 = in.nextInt();
System.out.println(" Input 2nd rational number for the 2nd Denominator");
rationalDen2 = in.nextInt();
if (rationalDen2 == 0){
System.out.println("Cannont divide by zero");
System.out.println(" please re enter another number");
break;
default:
System.err.println ( "Unrecognized option" );
break;
}
}
}
}
这是rational的类文件
public class Rational{
private int Numerator;
private int Denominator;
//constructors
public Rational(){
Numerator = 1;
Denominator = 1 ;
}
//setters
//a-numerator
//b-denmonator
//c other.getNumerator
//d-other.getDenominator
public void add (Rational other){ // (ad + bc) / bd
Numerator = (Numerator*other.getDenominator() + Denominator*other.getNumerator());
Denominator = (Denominator*other.getDenominator());
//Normalize();
}
public void subtract (Rational other){ // (ad-bc) / bd
Numerator = (Numerator*other.getDenominator() - Denominator*other.getNumerator());
Denominator = (Denominator*other.getDenominator());
//Normalize();
}
public void multiply (Rational other){ // ac/db
Numerator = (Numerator*other.getNumerator() / other.getDenominator()* Denominator);
// Normalize();
}
public void divide (Rational other){//
}
public int getNumerator(){
return Numerator;
}
public int getDenominator(){
return Denominator;
}
//toString
//public String toString(){
//return toString()+ (rationalNum1 + "/" + rationalDen1);
}
在你的主要课程中,你有:
Rational r1 = new Rational ( rationalNum1, rationalDen1);
Rational r2 = new Rational ( rationalNum2, rationalDen2);
您正在将2个整数传递给接收void的构造函数,因此您必须更改(Rational类的)构造函数,如下所示:
public Rational(int rationalNumber, int rationalDen){
Numerator = rationalNumber;
Denominator = rationalDen;
}
希望它有帮助,让我知道它是否有效,或者是否有更多的错误
编辑:扫描仪和打印错误。
你有这个:
public void question()
{
System.out.println("Do you want to exit? [y/n]"); // ask user if they want to quit with yes or no option
Scanner q = new Scanner(System.in);
switch (q.nextInt()) // here you are assuming that you are reading a int in step
{ // of a string
case 'y' : // ' ' arent used for strings...
System.out.println ("Thank you and goodbye.");
break;
case 'n' :
InputMenu();
break;
default:
System.err.println ( "Unrecognized option" );
break;
}
}
因此,您需要的是:
public void question()
{
System.out.println("Do you want to exit? [y/n]"); // ask user if they want to quit with yes or no option
Scanner q = new Scanner(System.in);
switch (q.nextLine()) // change nextInt to nextLine, that is the string method
{ // of a string
case "y" : //change ' ' to " "
System.out.println ("Thank you and goodbye.");
break;
case "n" : //change ' ' to " "
InputMenu();
break;
default:
System.err.println ( "Unrecognized option" );
break;
}
}
希望有帮助:)
编辑3:
您的代码中有:`
公营部门{
公共静态void main(字符串[]args){
因此,您可以做的是:
public class RationalDriver{
private static int rationalNum1, rationalDen1, rationalNum2, rationalDen2;
public static void main(String[] args){
// your main
}
我所做的是将仅存在于主变量中的局部变量转换为全局变量,这样当您想要更改它们的值或给它们一个值时,您只需执行以下操作:
rationalNum1 = your valor;
请注意,如果您使用任何变量而没有使用值初始化它,您将得到一个空点异常…您需要创建一个构造函数
Rational(int-rationalNum1,int-rationalDen1){}
在您的程序中,您使用了构造函数Rational(rationalNum1,rationalDen1)
当您只声明了默认构造函数public Rational()
,它不接受任何参数
一个类可以有多个构造函数,它们根据接受的参数的类型和数量来区分
例如
与
Class A(int c, int b);
但不是
Class(int a, float d)
不要上传代码,并期望人们阅读它,并试图推断出你所坚持的内容。告诉我们你遇到的具体问题。@BobbyDigital它不会编译。说构造函数Rational未定义,最后一个默认值是无效的labelIt完美工作,最后一件事是我对这个默认值有问题:System.err.println(“Unrecogned option”);break;}这有点帮助,但我现在的问题是,我的所有有理数m1有理数1等在case块下都不能解析为变量。我添加了一段新代码,只需将int-有理数m1,有理数1,有理数m2,有理数2;从main()移到如果您有更多问题,请告诉我,我可能明天才能回答,但我会回答:)好运气,我将如何设置rationalNum1=您的值;以及。我正在使用用户输入的值
Class A(int c, int b);
Class(int a, float d)