无法解析Java中字符串中的字符

Question

import java.util.Scanner;

public class Out {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        int n = input.nextInt();
        String[] arr = new String[n];
        int result = 0;
        for(int i = 0; i < n; i++) {
            arr[i] = input.next();
            System.out.println(arr[i]);
            System.out.println(Double.parseDouble(arr[i].replace(Character.toString(arr[i].charAt(arr[i].length() - 1)), "")));
            System.out.println(Double.parseDouble(Character.toString(arr[i].charAt(arr[i].length() - 1))));
            result += Math.pow(Double.parseDouble(arr[i].replace(Character.toString(arr[i].charAt(arr[i].length() - 1)), "")), Double.parseDouble(Character.toString(arr[i].charAt(arr[i].length() - 1))));


        }
        System.out.println(result);

    }

}

This code is supposed to get a string (eg 567) and raise 56 to the power of 7. It is NOT working only for the case when I have 212. I know it is very easy with arr[i]/10 and arr[i]%10. But I cannot understand the behavior here. I wanted to know why this solution is not working. Thank you!

Answer 1

String.replace will not work here. This function replaces all occurrences of the character in the string.

So for a number like 212, "212".replace("2", "") will result in "1".

See https://docs.oracle.com/javase/8/docs/api/java/lang/String.html#replace-char-char-

Consider using substring:

String s = "212"
System.out.println(s.substring(0, s.length() - 1)); //prints 21
System.out.println(s.substring(s.length()-1)); //prints 2