题解 | #计算某字符出现次数#

import java.io.*;

// 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) {
        // 创建一个{BufferedReader}读取字符输入的类，用{InputStreamReader}字节流转为{BufferedReader}字符流的类接受{System.in}标准输入流

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        try {
//            System.out.println("请输入一个由字母、数字和空格组成的字符串：");
            String inputString = br.readLine();

//            System.out.println("请输入一个字符：");
            char targetChar = (char) br.read(); // 读取单个字符

            int count = countCharacterOccurrences(inputString.toLowerCase(), Character.toLowerCase(targetChar));
//            System.out.println("字符 '" + targetChar + "' 在输入字符串中出现的次数为：" + count);
            System.out.println(count);

            br.close();
        } catch (IOException e) {
            System.out.println("发生输入输出异常：" + e.getMessage());
        }
    }

    public static int countCharacterOccurrences(String inputString,
            char targetChar) {
        int count = 0;

        for (int i = 0; i < inputString.length(); i++) {
            char currentChar = inputString.charAt(i);
            if (currentChar == targetChar) {
                count++;
            }
        }

        return count;
    }
}