Java:如何处理字符串索引超出范围错误？

Question

我是 Java 新手，不知道如何解决这个问题:线程“main”中的异常 java.lang.StringIndexOutOfBoundsException:字符串索引超出范围:1

完整代码如下:

public static void main(String[] args) {

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

    //Step 1:  Ask user to enter first and last name
    System.out.println("\nPlease enter your first and last name: ");
    String name = input.nextLine();
    String major = "";
    String classification = "";

    //Step 2: Ask user to enter two characters
    System.out.println("\nPlease enter two characters (1st character represents   the major and 2nd character represents the classification): ");
    char ch = input.next().charAt(0);
    char ch1 = input.nextLine().charAt(1);

    //Step 3:  Print statement 
    switch(ch) {
        case 'i': major = "Information Technology"; break;
        case 'c': major = "Computer Science"; break; 
        case 'm': major = "Mathematics"; break;
        case 'p': major = "Physics"; break;    
        case 'b': major = "Biology"; break;
        case 'e': major = "Engineering"; break;
        case 'h': major = "History"; break; 
        case 'j': major = "Journalism"; break;
        case 'a': major = "Art and Design"; break;
        case 'l': major = "Literature"; break;
        case 's': major = "Sport Medicine"; break;
        default: System.out.println("\nInvalid Major Code");
            System.out.println("Please enter a character followed by an integer!");
        break;
    }//end of switch

    //Step 3:  Print statement 
    switch(ch1) {
        case '1': classification = "Freshman"; break;
        case '2': classification = "Sophmore"; break;
        case '3': classification = "Junior"; break;
        case '4': classification = "Senior"; break;    
        case '5': classification = "Graduate"; break;
        default: System.out.println("\nInvalid Classification Code");
            System.out.println("Please enter a character followed by an integer!");
            break;
    }//end of switch

    System.out.println("\nMajor and classification is: " + major + "" + classification);
    System.out.println("\nThank You!");
}//end of main

任何帮助将不胜感激。

Answer 1

尝试更改您的代码，以便它首先检查输入的长度，然后再引用字符串的索引。类似于以下内容:

 //Step 2: Ask user to enter two characters
System.out.println("\nPlease enter two characters (1st character represents   the major and 2nd character represents the classification): ");
String inputNext = input.next();
String inputNextLine;
if(inputNext.length>0 && inputNextLine.length>0){
char ch = inputNext;
char ch1 = inputNextLine;


//Step 3:  Print statement 
switch(ch) 
{
    case 'i': major = "Information Technology";
    break;
    case 'c': major = "Computer Science";
    break;
    case 'm': major = "Mathematics";
    break;
    case 'p': major = "Physics";
    break;    
    case 'b': major = "Biology";
    break;
    case 'e': major = "Engineering";
    break;
    case 'h': major = "History";
    break; 
    case 'j': major = "Journalism";
    break;
    case 'a': major = "Art and Design";
    break;
    case 'l': major = "Literature";
    break;
    case 's': major = "Sport Medicine";
    break;

    default: System.out.println("\nInvalid Major Code");
    System.out.println("Please enter a character followed by an integer!");
    break;

}//end of switch

//Step 3:  Print statement 
switch(ch1)
{
    case '1': classification = "Freshman";
    break;
    case '2': classification = "Sophmore";
    break;
    case '3': classification = "Junior";
    break;
    case '4': classification = "Senior";
    break;    
    case '5': classification = "Graduate";
    break;
}
}