Java - 字符串索引超出範圍錯誤

Question

當我嘗試從用戶收集字符串輸入並將其轉換爲字符類型時，我總是收到超出範圍的錯誤。這裏是我的代碼： 編輯：我的問題沒有得到回答。我在我的charAt語句中添加了一個參數，但它仍然不起作用。當我運行它時，它告訴我問題出現在第33行。這個問題不是我得到的任何鏈接的重複。我無法理解這個所謂的類似問題。請問有人能告訴我第33行有什麼問題嗎？

//Arthur Fidas 
import java.util.Scanner; //Needed for Scanner class 
import java.lang.String; 
/** 
    This program computes and displays the shipping charges for Fed Ex. 
*/ 

public class FedEx 
{ 
    public static void main (String[] args) 
    { 
     final double ZONE_A = .6, ZONE_B = 1.0, ZONE_C = 1.25, ZONE_D = 1.4; 
     String input; 
     char zone; 
     String name; 
     double weight; 
     double total = 0.0; 
     int serviceCode; 
     int hazardCode; 
     double hazardCodeCalculation; 

     //Create a Scanner object for keyboard input 
     Scanner keyboard = new Scanner (System.in); 

     //Prompt user for package weight 
     System.out.println("What is the weight of the package?: "); 
     weight = keyboard.nextDouble(); 

     //Prompt user for Zone 
     System.out.print("Enter the zone letter: "); 
     input = keyboard.nextLine(); 
     zone = input.charAt(0); 

     //Calculate zone price 
     switch(zone) 
     { 
      case 'a': 
      case 'A': 
       total = weight*ZONE_A; 
       break; 
      case 'b': 
      case 'B': 
       total = weight*ZONE_B; 
       break; 
      case 'c': 
      case 'C': 
       total = weight*ZONE_C; 
       break; 
      case 'd': 
      case 'D': 
       total = weight*ZONE_D; 
       break; 
      default: 
       System.out.println("Please enter A, B, C, or D."); 
       break; 
     } 

     //Prompt user for service charge 
     System.out.println("Enter the Special Service number: "); 
     serviceCode = keyboard.nextInt(); 

     //Caculate Service Charge 
     if (serviceCode == 1) 
     { 
      total += 0; 
     } 
     else if (serviceCode == 2) 
     { 
      total += 10; 
     } 
     else if (serviceCode == 3) 
     { 
      total += 25; 
     } 
     else 
     { 
      System.out.println("Please enter 1, 2, or 3."); 
     } 
     //Prompt user for Hazard Code 
     System.out.println("Enter the Hazard Code number :"); 
     hazardCode = keyboard.nextInt(); 

     //Calculate Hazard Charge 
     switch(hazardCode) 
     { 
      case 1: 
       total += 0; 
       break; 
      case 2: 
       hazardCodeCalculation = total * .1; 
       total += hazardCodeCalculation; 
       break; 
      case 3: 
       hazardCodeCalculation = total * .25; 
       total += hazardCodeCalculation; 
       break; 
      default: 
       System.out.println("Please enter either 1, 2, or 3."); 
       break; 
     } 
    } 
} 

Answer 1

其實我在代碼部分發現了一些問題。

//Prompt user for Zone 
     System.out.print("Enter the zone letter: "); 
     input = keyboard.nextLine(); 
     zone = input.charAt(); 

首先，您正在使用.nextLine()方法可能會產生問題的字符串輸入。有關更多信息，請參閱this。

另一個問題是，你沒有給區域分配任何字符，而是你應該通過想要的字符在.charAt()方法。

所以你可以在two的方法中做到這一點，以防萬一你想要輸入的第一個字符String。對於另一個字符，改變.charAt()方法中的索引值。

1）

//Prompt user for Zone 
    System.out.print("Enter the zone letter: "); 
    keyboard.nextLine(); //Storing that Enter key Input (Garbage value) 
    input = keyboard.nextLine(); 
    zone = input.charAt(0); 

2）

//Prompt user for Zone 
    System.out.print("Enter the zone letter: "); 
    input = keyboard.next(); //In case your String input doesn't contain Space in between. 
    zone = input.charAt(0); 

如果只想one character爲input拿，你可以把character輸入，而不是String。

//Prompt user for Zone 
    System.out.print("Enter the zone letter: "); 
    zone = keyboard.next().charAt(0); 

更正後的代碼

//Arthur Fidas 
import java.util.Scanner; //Needed for Scanner class 
import java.lang.String; 
/** 
    This program computes and displays the shipping charges for Fed Ex. 
*/ 

public class FedEx 
{ 
    public static void main (String[] args) 
    { 
     final double ZONE_A = .6, ZONE_B = 1.0, ZONE_C = 1.25, ZONE_D = 1.4; 
     String input; 
     char zone; 
     String name; 
     double weight; 
     double total = 0.0; 
     int serviceCode; 
     int hazardCode; 
     double hazardCodeCalculation; 

     //Create a Scanner object for keyboard input 
     Scanner keyboard = new Scanner (System.in); 

     //Prompt user for package weight 
     System.out.println("What is the weight of the package?: "); 
     weight = keyboard.nextDouble(); 

     /*THIS FOLLOWING PORTION CAN BE CHANGED WITH PROVIDED SOLUTIONS, TRY ANY OF THEM*/ 

     //Prompt user for Zone        
     System.out.print("Enter the zone letter: "); 
     input = keyboard.next(); 
     zone = input.charAt(0); 

     /*TILL THIS*/ 

     //Calculate zone price 
     switch(zone) 
     { 
      case 'a': 
      case 'A': 
       total = weight*ZONE_A; 
       break; 
      case 'b': 
      case 'B': 
       total = weight*ZONE_B; 
       break; 
      case 'c': 
      case 'C': 
       total = weight*ZONE_C; 
       break; 
      case 'd': 
      case 'D': 
       total = weight*ZONE_D; 
       break; 
      default: 
       System.out.println("Please enter A, B, C, or D."); 
       break; 
     } 

     //Prompt user for service charge 
     System.out.println("Enter the Special Service number: "); 
     serviceCode = keyboard.nextInt(); 

     //Caculate Service Charge 
     if (serviceCode == 1) 
     { 
      total += 0; 
     } 
     else if (serviceCode == 2) 
     { 
      total += 10; 
     } 
     else if (serviceCode == 3) 
     { 
      total += 25; 
     } 
     else 
     { 
      System.out.println("Please enter 1, 2, or 3."); 
     } 
     //Prompt user for Hazard Code 
     System.out.println("Enter the Hazard Code number :"); 
     hazardCode = keyboard.nextInt(); 

     //Calculate Hazard Charge 
     switch(hazardCode) 
     { 
      case 1: 
       total += 0; 
       break; 
      case 2: 
       hazardCodeCalculation = total * .1; 
       total += hazardCodeCalculation; 
       break; 
      case 3: 
       hazardCodeCalculation = total * .25; 
       total += hazardCodeCalculation; 
       break; 
      default: 
       System.out.println("Please enter either 1, 2, or 3."); 
       break; 
     } 
    } 
}