public static void main(String[] args) {

        System.out.println(isValidDate("2020-12-12 14:30:20", null));//true

        System.out.println(isValidDate("19-12-12 14:30:20", null));//false

        System.out.println(isValidDate("2020/12/12 14:30:20", null));//false

        System.out.println(isValidDate("2020-12-12 14:30", null));//false

    }

    public static boolean isValidDate(String str, String format) {

        if (format == null) {

            format = "yyyy-MM-dd HH:mm:ss";

        }

        boolean convertSuccess = true;

        // 指定日期格式

        SimpleDateFormat sdf = new SimpleDateFormat(format);

        try {

            sdf.setLenient(false);

            sdf.parse(str);

            if (str.length() != format.length()) {

                convertSuccess = false;

            }

        } catch (ParseException e) {

            // 如果throw java.text.ParseException或者NullPointerException，就说明格式不对

            convertSuccess = false;

        }

        return convertSuccess;

    }