如何计算序列在Java字符串中出现的次数？

public class CountOccurrences {
    public static void main(String[] args) {
        String str = "这是一个测试字符串，测试字符串中的序列出现的次数。";
        String subStr = "测试";
        int count = countOccurrences(str, subStr);
        System.out.println("序列出现的次数：" + count);
    }

    public static int countOccurrences(String str, String subStr) {
        int count = 0;
        int index = str.indexOf(subStr);
        while (index != -1) {
            count++;
            index = str.indexOf(subStr, index + 1);
        }
        return count;
    }
}