Java：线程“main”中的异常java.lang.StringIndexOutOfBoundsException：字符串索引超出范围： [英] Java : Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range:

问题描述

初学者，任何人都可以帮我弄清楚我们在做什么。我试图读取一个String并将String的每个字符存储在一个数组中。

Am a beginner, could anyone help me figure out what us going on. Am Trying to read a String and store each character of the String in an Array.

import java.util.Scanner;

public class CoreMainDigitExtractor {

    static Scanner inputString = new Scanner(System.in);

    public static void main(String[] args) {


        digitExtractor ExtracDig = new digitExtractor();

        System.out.println("Enter a String to Extract and Display Vertically in Reverse Order : ");
        String input1 = inputString.nextLine();
        System.out.println("User input String is : " + input1);
        System.out.println("Calling Method 'OrderByMaths' in Object 'ExtracDig' of Class 'digitExtractor', with User Input String....'"+input1+"'");    
        ExtracDig.OrderbyMaths(input1);

    }

}




public class digitExtractor {

    int tNumber;

    public digitExtractor() {
        // TODO Auto-generated constructor stub
    }

    public void OrderbyMaths(String numberSequence) {
        System.out.println("OrderbyMatch : Inside Method 'OrderbyMaths'....");
        System.out.println("OrderbyMatch : Initializing a variable of type int 'tNumberLength'.");
        int tNumberLength = numberSequence.length();
        System.out.println("OrderbyMatch : Variable Initialized of type int 'tNumberLength'.");
        System.out.println("OrderbyMaths : Capture length of User Input String into Variable 'tNumberLength'.");
        System.out.println("OrderbyMaths : The length of User Input String in Variable 'tNumberLength' is '" + tNumberLength + "'.");
        System.out.println("OrderbyMatch : Initializing an Array of type int 'arrNumberSequence'; with Size of Array equal to 'tNumberLength'.");
        char arrNumberSequence[] = new char[tNumberLength];
        System.out.println("OrderbyMatch : Initialized Array 'arrNumberSequence' with Size '" + arrNumberSequence.length + "'");
        int i = 0;

        while (i <= arrNumberSequence.length){
            arrNumberSequence[i] = numberSequence.charAt(i);
            System.out.println("OrderbyMatch : Value in Array Slot '"+arrNumberSequence[i]+"' is '"+ numberSequence.charAt(i)+"'");
            i++;    

        }

    }   

}

输出

输入一个字符串以反向顺序提取并垂直显示：

Enter a String to Extract and Display Vertically in Reverse Order :

HACK

用户输入字符串是：HACK

User input String is : HACK

在类'digitExtractor的对象'ExtracDig'中调用方法'OrderByMaths' '，用户输入字符串....'HACK'

Calling Method 'OrderByMaths' in Object 'ExtracDig' of Class 'digitExtractor', with User Input String....'HACK'

OrderbyMatch：内部方法'OrderbyMaths'....

OrderbyMatch : Inside Method 'OrderbyMaths'....

OrderbyMatch：初始化int'tNumberLength'类型的变量。

OrderbyMatch : Initializing a variable of type int 'tNumberLength'.

OrderbyMatch：变量初始化类型为int'tNumberLength'。

OrderbyMatch : Variable Initialized of type int 'tNumberLength'.

OrderbyMaths：将用户输入字符串的长度捕获到变量'tNumberLength'。

OrderbyMaths : Capture length of User Input String into Variable 'tNumberLength'.

OrderbyMaths：变量'tNumberLength'中用户输入字符串的长度为'4'。

OrderbyMaths : The length of User Input String in Variable 'tNumberLength' is '4'.

OrderbyMatch：初始化int'arrNumberSequence'类型的数组;数组大小等于'tNumberLength'。

OrderbyMatch : Initializing an Array of type int 'arrNumberSequence'; with Size of Array equal to 'tNumberLength'.

OrderbyMatch：初始化数组'arrNumberSequence'，大小'4'

OrderbyMatch : Initialized Array 'arrNumberSequence' with Size '4'

OrderbyMatch：数组插槽中的值'H'是'H'

OrderbyMatch : Value in Array Slot 'H' is 'H'

OrderbyMatch：数组插槽中的值'A'是'A'

OrderbyMatch : Value in Array Slot 'A' is 'A'

OrderbyMatch：数组插槽中的值'C'是'C'

OrderbyMatch : Value in Array Slot 'C' is 'C'

OrderbyMatch：数组插槽中的值'K'是'K'

OrderbyMatch : Value in Array Slot 'K' is 'K'

线程main中的异常java.lang.StringIndexOutOfBoundsException：字符串索引超出范围：4
at java.lang.String.charAt（Unknown Source）
at digitExtractor.OrderbyMaths（digitExtractor.java:23）
at CoreMainDigitExtractor.main（CoreMainDigitExtractor.java:16）

Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: 4 at java.lang.String.charAt(Unknown Source) at digitExtractor.OrderbyMaths(digitExtractor.java:23) at CoreMainDigitExtractor.main(CoreMainDigitExtractor.java:16)

问候

Dwenish

推荐答案

对于字符串 HACK 我们有 .length 4 。 Java中的索引从0开始，所以我们有

For the string HACK we have a .length of 4. Indexes in Java start at 0 so we have

['H','A','C','K']
  ^   ^   ^   ^ 
  0   1   2   3

所以，请在你的while循环 i = 4

So lets say in your while loop i=4

while (i <= arrNumberSequence.length)
while (is 4 less than or equal to 4? yes 4==4 so continue with the loop) 

当我们尝试访问 charAt（4）时，它不是我们字符串的有效索引

When we try to access charAt(4) it is not a valid index for our string

['H','A','C','K']
  ^   ^   ^   ^   ^
  0   1   2   3   4

因此我们得到例外

java.lang.StringIndexOutOfBoundsException: String index out of range: 4

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