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 in = new Scanner(System.in);
        String inputStr = in.nextLine(); //字符串
        String inputTarget = in.nextLine(); //目标字符串
        System.out.println(countStr(inputStr, inputTarget));
    }

    private static int countStr(String str, String target) {
        str = str.toLowerCase();
        target = target.toLowerCase();
        String newStr = str.replaceAll(target, ""); //将str中的target全部替换为""
        return str.length() - newStr.length();
    }
}