如果其他语句（初学者）

Question

我有一个学校的任务和我的生活我无法弄清楚为什么我的else语句不打印出我需要它的线。如果用户输入1,2,3,4或5以外的任何内容，我需要它输出无效的条目。

这是我到目前为止有：

/** 
*Proj2.java 
*This project will be able to ask the user which category 
    they fall in to and then ask how many tickets they want and 
    if they want parking added. 
    It will then calculate the total cost for all tickets, with discounts 
    and parking. 
*/ 

import java.util.Scanner; 
import java.text.DecimalFormat; 

public class Proj2 { 

    public static void main(String[] args) { 
    { Scanner s = new Scanner (System.in); 

final double general = 80; 
final double parking = 25; 
final double alumniDiscount = .1; 
final double facultyDiscount = .15; 
final double militaryDiscount = .2; 
final double studentDiscount = .5; 
//This declares all the constants for this program 

int numberOfTickets = 0; 
int selection = 0; 
double ticketsPrice = 0; 
double finalCost = 0; 
//declares the variables 

DecimalFormat df = new DecimalFormat("0.00"); 

System.out.println("\n**Welcome to the KSU Homecoming ticketing app for Fall 2014**"); 
System.out.println("\t -----Show your Purple Pride!-----\n\n\n"); 

//this displays the header for the customer 

System.out.println("Please select from the following categories:\n\n" 
+ "1) Student\n" 
+ "2) Alumni\n" 
+ "3) Faculty & Staff\n" 
+ "4) Military\n" 
+ "5) General Public\n"); 

//this list out all the options the customer can choose from 

System.out.print("Selection: "); 
selection = Integer.parseInt (s.nextLine()); 


System.out.print("\nPlease enter the number of tickets you would like to purchase: "); 
numberOfTickets = Integer.parseInt(s.nextLine()); 


System.out.print("\nWould you like to purchase a parking pass for the game?\n" 
+ "Select Y or N: "); 
char parkingChoice= (s.nextLine()).charAt(0); 

//questions for the user to input their answer 


if (selection == 1) { 
ticketsPrice = ((general - (general * studentDiscount)) * numberOfTickets); 
} 

else if (selection == 2) { 
ticketsPrice = ((general - (general * alumniDiscount)) * numberOfTickets); 
} 

else if (selection == 3) { 
ticketsPrice = ((general - (general * facultyDiscount)) * numberOfTickets); 
} 

else if (selection == 4) { 
ticketsPrice = ((general - (general * militaryDiscount)) * numberOfTickets); 
} 

else if (selection == 5) { 
ticketsPrice = general * numberOfTickets; 
} 

else { 
System.out.println("Invalid Category selection"); 
} 


//calculations based on which selection the user chooses 

if (parkingChoice == 'Y' || parkingChoice == 'y') { 
finalCost = ticketsPrice + parking; 
System.out.println("\n\nYou ordered " + numberOfTickets + " tickets" + " with parking for a total  cost of: $" + df.format(finalCost)+"\n"); 
} 
else if (parkingChoice == 'N' || parkingChoice == 'n') { 
finalCost = ticketsPrice; 
System.out.println("\n\nYou ordered " + numberOfTickets + " tickets" + " without parking for a total cost of: $" + df.format(finalCost)+"\n"); 
} 

//whether to add parking or not 


System.out.println("Enjoy the game and a Wildcat Victory!"); 


    } // end main 
} // end class 

} 

它符合和适用于数学，这不是我的错误信息。任何帮助表示赞赏！

Answer 1

如果在请求下一行输入之前验证输入，它是否工作？ （即将输入扫描码与逻辑流程内联地移动）

Answer 2

你的程序工作得很好。我认为这个问题是你要每次输入和时间检查输入的有效性不是之后的所有数据由用户已经输入了：

public static void main(String[] args) 
{ 

    Scanner s = new Scanner(System.in); 

    final double general = 80; 
    final double parking = 25; 
    final double alumniDiscount = .1; 
    final double facultyDiscount = .15; 
    final double militaryDiscount = .2; 
    final double studentDiscount = .5; 
    // This declares all the constants for this program 

    int numberOfTickets = 0; 
    int selection = 0; 
    double ticketsPrice = 0; 
    double finalCost = 0; 
    // declares the variables 

    DecimalFormat df = new DecimalFormat("0.00"); 

    System.out.println("\n**Welcome to the KSU Homecoming ticketing app for Fall 2014**"); 
    System.out.println("\t -----Show your Purple Pride!-----\n\n\n"); 

    // this displays the header for the customer 

    System.out.println("Please select from the following categories:\n\n" + "1) Student\n" + "2) Alumni\n" + "3) Faculty & Staff\n" + "4) Military\n" + "5) General Public\n"); 

    // this list out all the options the customer can choose from 

    System.out.print("\nPlease enter the number of tickets you would like to purchase: "); 
    numberOfTickets = Integer.parseInt(s.nextLine()); 

    if (numberOfTickets < 0) 
    { 
     System.out.println("Invalid number of tickets"); 
     return; 
    } 

    System.out.print("Selection: "); 
    selection = Integer.parseInt(s.nextLine()); 

    // questions for the user to input their answer 

    if (selection == 1) 
    { 
     ticketsPrice = ((general - (general * studentDiscount)) * numberOfTickets); 
    } 

    else if (selection == 2) 
    { 
     ticketsPrice = ((general - (general * alumniDiscount)) * numberOfTickets); 
    } 

    else if (selection == 3) 
    { 
     ticketsPrice = ((general - (general * facultyDiscount)) * numberOfTickets); 
    } 

    else if (selection == 4) 
    { 
     ticketsPrice = ((general - (general * militaryDiscount)) * numberOfTickets); 
    } 

    else if (selection == 5) 
    { 
     ticketsPrice = general * numberOfTickets; 
    } 

    else 
    { 
     System.out.println("Invalid Category selection"); 
     return; 
    } 



    System.out.print("\nWould you like to purchase a parking pass for the game?\n" + "Select Y or N: "); 
    char parkingChoice = (s.nextLine()).charAt(0); 

    if (parkingChoice == 'Y' || parkingChoice == 'y') 
    { 
     finalCost = ticketsPrice + parking; 
     System.out.println("\n\nYou ordered " + numberOfTickets + " tickets" + " with parking for a total  cost of: $" + df.format(finalCost) + "\n"); 
    } 
    else if (parkingChoice == 'N' || parkingChoice == 'n') 
    { 
     finalCost = ticketsPrice; 
     System.out.println("\n\nYou ordered " + numberOfTickets + " tickets" + " without parking for a total cost of: $" + df.format(finalCost) + "\n"); 
    } 
    else 
    { 
     System.out.println("Invalid parking choice"); 
     return; 

    } 
    // whether to add parking or not 

    System.out.println("Enjoy the game and a Wildcat Victory!"); 

} 

PS：这将是这样一些switch更好的多声明:)

编辑：更改代码先设置numberOfTickets。感谢Cyber​​neticTwerkGuruOrc注意到这一点。

Answer 3

只是做一个简单的检查，只要你得到selection输入：

//beginning code goes here 
System.out.print("Selection: "); 
selection = Integer.parseInt (s.nextLine()); 

//simple check 
if(selection < 1 || selection > 5){ 
    System.out.println("Invalid Category selection"); 
}else{ 
    System.out.print("\nPlease enter the number of tickets you would like to purchase: "); 
    numberOfTickets = Integer.parseInt(s.nextLine()); 
    System.out.print("\nWould you like to purchase a parking pass for the game?\n" + "Select Y or N: "); 
    char parkingChoice= (s.nextLine()).charAt(0); 

    switch(selection){ 
     case 1: 
      ticketsPrice = ((general - (general * studentDiscount)) * numberOfTickets); 
      break; 
     case 2: 
      ticketsPrice = ((general - (general * alumniDiscount)) * numberOfTickets); 
      break; 
     case 3: 
      ticketsPrice = ((general - (general * facultyDiscount)) * numberOfTickets); 
      break; 
     case 4: 
      ticketsPrice = ((general - (general * militaryDiscount)) * numberOfTickets); 
      break; 
     case 5: 
      ticketsPrice = general * numberOfTickets; 
      break; 
     default://this case is not needed. i kept it in so its easier to understand. 
      System.out.println("Invalid Category selection"); 
      break; 
    } 

    //calculations based on which selection the user chooses 
    if (parkingChoice == 'Y' || parkingChoice == 'y') { 
     finalCost = ticketsPrice + parking; 
     System.out.println("\n\nYou ordered " + numberOfTickets + " tickets" + " with parking for a total  cost of: $" + df.format(finalCost)+"\n"); 
    } 
    else if (parkingChoice == 'N' || parkingChoice == 'n') { 
     finalCost = ticketsPrice; 
     System.out.println("\n\nYou ordered " + numberOfTickets + " tickets" + " without parking for a total cost of: $" + df.format(finalCost)+"\n"); 
    } 
    //whether to add parking or not 
    System.out.println("Enjoy the game and a Wildcat Victory!"); 
} 
//ending code goes here. 

注意：@ortis原来的答案将无法正常工作（虽然它得到了upvotes：/），因为numberOfTickets ISN” t由用户指定，直到后来在他/她的解决方案中。