题解 | #计算某字符出现次数#

import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String str = scanner.nextLine();//输入字符串
        char c = scanner.next().charAt(0);//输入一个字符

        int ret = test(str, c);
        System.out.println(ret);
    }

    public static int test(String str, char c) {
        //不区分大小写，那我可以先把他们都转为一个形式，比如都小写
        String str2 = str.toLowerCase();//字符串转成小写
        Character[] arr = new Character[str2.length()];
        for (int i = 0; i < str2.length(); i++) {
            arr[i] = str2.charAt(i);
        }//目的就是把输入的字符串变成字符数组
        //arr[str2.length()]=str2.charAt(str2.length());//会数组越界
        char c2 = Character.toLowerCase(c);//一个字符变小写
        //开始比较，如果相等，则count+1
        int count = 0;
        for (int i = 0; i < arr.length; i++) {
            if (c2 == arr[i]) {
                count++;
            }
        }
        return count;
    }
}