Question

我正在尝试创建一个代码来确定电话帐单的费用。

到目前为止，这是我的代码

import java.util.Scanner;
public class PhoneBill
{
  public static void main(String[] args)
  {
  // Create Scanner
  Scanner input = new Scanner (System.in);

  //Declare variables
  double minutes, nightm, daym, totalminutes, totalcost, daycost, nightcost;
  int account;

  //Obtain account number
  System.out.println("Enter your account number: ");
  account = input.nextInt(); 

  //Determine service
  System.out.println("Enter r for regular service or p for premium service: ");
  char service = input.next(".").charAt(0);

  //Logic for regular service
  if (service == 'r')
     System.out.println("Enter number of minutes talked: ");
     minutes = input.nextDouble();

     if (minutes >= 50)
     totalcost = (10.00 + ((minutes - 50) * 0.20));

     else
     totalcost = (10.00);

  //Logic for premium service
  else if (service == 'p')
     System.out.println("Enter number of minutes used from 6:00AM to 6:00PM");
     daym = input.nextDouble();

     System.out.println("Enter number of minutes used from 6:00PM to 6:00AM");
     nightm = input.nextDouble();

  //Obtain cost for daytime minutes
     if (daym < 75)
        daycost = 0;
     else
        daycost = ((daym - 75) * .10);

  //Obtain cost for night minutes
     if (nightm < 100)
        nightcost = 0;
     else
        nightcost = ((nightm - 100) * .05);

  //Obtain total cost of premium service

  totalcost = daycost + nightcost;      

  //Display account
  System.out.println ("The account number is: " + account);

  //Display service type
  if (service == 'r')
     System.out.println ("You have selected regular service");

  else if (service == 'p')
     System.out.println ("You have selected premium service");

  //Display results
  if (service == 'r')
     System.out.println ("Total minutes used is " + minutes);
     System.out.println ("Total ammount due is $" + totalcost);     
  else if (service == 'p')
     System.out.println ("Minutes used during the day is: " + daym);
     System.out.println ("Minutes used during the night is: " + nightm);
     System.out.println ("Total minutes used is: " + (daym + nightm));
     System.out.println ("The amount due is: $" + totalcost);
  }
}

我觉得我很亲密，但它一直给我这个错误

PhoneBill.java:41: error: 'else' without 'if'
      else if (service == 'p')

PhoneBill.java:78: error: 'else' without 'if'
      else if (service == 'p')

我有上述陈述的陈述，但它仍然告诉我，我没有。

我没看到什么？

Answer 1

如果内部代码块超过一行，则需要在If Else语句中使用括号。我总是使用括号来提高代码的可读性。

      Scanner input = new Scanner (System.in);

      //Declare variables
      double minutes=0, nightm=0, daym=0, totalminutes=0, totalcost=0, daycost=0, nightcost=0;
      int account;

      //Obtain account number
      System.out.println("Enter your account number: ");
      account = input.nextInt(); 

      //Determine service
      System.out.println("Enter r for regular service or p for premium service: ");
      char service = input.next(".").charAt(0);

      //Logic for regular service
      if (service == 'r'){
         System.out.println("Enter number of minutes talked: ");
         minutes = input.nextDouble();

         if (minutes >= 50)
         totalcost = (10.00 + ((minutes - 50) * 0.20));

         else
         totalcost = (10.00);

      //Logic for premium service
      }else if (service == 'p'){
         System.out.println("Enter number of minutes used from 6:00AM to 6:00PM");
         daym = input.nextDouble();

         System.out.println("Enter number of minutes used from 6:00PM to 6:00AM");
         nightm = input.nextDouble();

      //Obtain cost for daytime minutes
         if (daym < 75)
            daycost = 0;
         else
            daycost = ((daym - 75) * .10);

      //Obtain cost for night minutes
         if (nightm < 100)
            nightcost = 0;
         else
            nightcost = ((nightm - 100) * .05);
      }
      //Obtain total cost of premium service

      totalcost = daycost + nightcost;      

      //Display account
      System.out.println ("The account number is: " + account);

      //Display service type
      if (service == 'r'){
         System.out.println ("You have selected regular service");

      }else if (service == 'p'){
         System.out.println ("You have selected premium service");
      }
      //Display results
      if (service == 'r'){
         System.out.println ("Total minutes used is " + minutes);
         System.out.println ("Total ammount due is $" + totalcost);     
      }else if (service == 'p'){
         System.out.println ("Minutes used during the day is: " + daym);
         System.out.println ("Minutes used during the night is: " + nightm);
         System.out.println ("Total minutes used is: " + (daym + nightm));
         System.out.println ("The amount due is: $" + totalcost);
      }

Answer 2

如果您要在if/else if/else语句下有多行，则需要使用大括号{}：

if (service == 'r') {
    // your code
} else if (service == 'p') {
    // your code
}

我个人总是使用它们，但是有些人喜欢将它们排除在单行之外。

Answer 3

您的代码中的错误是您没有为if，else和else if语句打开花括号。如果不包括指示if语句要覆盖的大括号，则if语句将仅执行其后的第一行（假设if语句为true）。尝试添加花括号以涵盖if else语句的范围，并检查代码是否有效。

Answer 4

你只是挂了基本语法

if（case）语句如果

下面只有一个条件，则不带括号

if(case)
    dothis();

如果有多行需要if语句执行，则需要用大括号括起来。

if(case){
    dothis();
    dothat();
}

这告诉程序在满足大小写时调用dothis（）和dothat（）。

我建议关闭括号中的所有if / else语句，因为它可以帮助您完全避免这个问题。

告诉变量尚未初始化

4 个答案: