public static String toCamelCase(CharSequence str, char symbol) {
        if (null == str || str.length() == 0) {
            return null;
        }
        int length = str.length();
        StringBuilder sb = new StringBuilder(length);
        boolean upperCase = false;
        for (int i = 0; i < length; ++i) {
            char c = str.charAt(i);
            if (c == symbol) {
                upperCase = true;
            } else if (upperCase) {
                sb.append(Character.toUpperCase(c));
                upperCase = false;
            } else {
                sb.append(c);
            }
        }
        return sb.toString();
    }
@Test
    public void toCamelCase() {
        String string = "str_str";
        String s = StringUtil.toCamelCase(string, StringUtil.UNDERLINE);
        Assert.assertEquals("strStr", s);
    }