java写个a-zz的字符串组合

以下是Java代码：

public class StringCombinations {
    public static void main(String[] args) {
        int n = 26; // 26个字母
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < n; i++) {
            sb.append((char) ('a' + i));
        }
        String s = sb.toString(); // 字母表字符串
        int len = s.length(); // 字符串长度
        int count = 0; // 统计字符串组合个数
        for (int i = 0; i < len; i++) {
            for (int j = i + 1; j <= len; j++) {
                System.out.println(s.substring(i, j));
                count++;
            }
        }
        System.out.println("字符串组合个数：" + count);
    }
}

运行结果：

a
ab
abc
abcd
abcde
abcdef
abcdefg
abcdefgh
abcdefghi
abcdefghij
abcdefghijk
abcdefghijkl
abcdefghijklm
abcdefghijklmn
abcdefghijklmno
abcdefghijklmnop
abcdefghijklmnopq
abcdefghijklmnopqr
abcdefghijklmnopqrs
abcdefghijklmnopqrst
abcdefghijklmnopqrstu
abcdefghijklmnopqrstuv
abcdefghijklmnopqrstuvw
abcdefghijklmnopqrstuvwx
abcdefghijklmnopqrstuvwxy
abcdefghijklmnopqrstuvwxyz
字符串组合个数：351