用Java尝试写BF字符串匹配问题，出现错误

Question

 import java.util.Scanner;

public class BF {
    public static void main(String[] args) {
        String S = new String();           //主串S
        String T = new String();           //模式串T
        int pos;
        int result;

        Scanner console = new Scanner(System.in);
        S = console.nextLine();
        T = console.nextLine();
        pos = console.nextInt();

        System.out.printf("%s\n", S);
        System.out.printf("%s\n", T);
        System.out.printf("%d\n", pos);

        result = Index(S, T, pos);

        System.out.printf("%d\n", result);
    }

    private static int Index(String S, String T, int pos){
        int i = pos;
        int j = 1;

        while(i <= S.length() && j <= T.length()){
            if(S.charAt(i) == T.charAt(j)){       //char.At方法是取出字符串中的字符
                i++;
                j++;
            }
            else{
                i = i-j+2;
                j = 1;
            }
        }

        if(j > T.length()){
            return i-T.length();
        }
        else{
            return 0;
        }
    }
}

Answer 1

你这个是角标越界异常。i <= S.length() && j <= T.length()是有问题的，字符串角标是从0开始的，所以你要改成i < S.length() && j <T.length()或者
i <= S.length()-1 && j <= T.length()-1就可以了