java基础，取出字符串前后逗号

根据"，"截取字符串长度，for循环

    @Test
    public void testTiii() {
        String a = "";
        String b = "";
        String c = "hhh";

        //第一
        for (int i = 0; i < 2; i++) {
            a += b + ",";
        }

        //第二
        for (int i = 0; i < 2; i++) {
            a += b + ",";
            b = "ddsd";
        }
        System.out.println("a=" + a);

        //第三
        for (int i = 0; i < 2; i++) {
            a += c + ",";
        }
        System.out.println("a=" + a);


        for (int i = 0; i < a.split(",").length; i++) {
            if (a.startsWith(",")) {
                a = a.substring(1,a.length());
            }
            if (a.endsWith(",")) {
                a = a.substring(0, a.length() - 1);
            }
        }

        System.out.println("a=" + a);

    }