如何统计一个字符串中某个字符出现的次数

将字符串直接进行遍历或者将字符串转变为字符数组，然后进行遍历：

public static void main(String[] args) {
    String str = "ABCDEFABC";
    char searchChar = 'B';

    int count = 0;
    char[] charArray = str.toCharArray();
    for (char item : charArray) {
        if (item == searchChar) {
            count++;
        }
    }
    System.out.println("字符" + searchChar + "出现的次数为" + count);
}

 换一种思路：使用replace()方法，很好理解，并且高效。

public static void main(String[] args) {
    String str = "ABCDEFABC";
    String searchChar = "B";
    int count = 0;

    int origialLength = str.length();
    str = str.replace(searchChar, "");
    int newLength = str.length();

    count = origialLength - newLength;

    System.out.println("字符" + searchChar + "出现的次数为" + count);
}