DateFormat采坑

无意发现一个dateformat的问题

DateFormat dateFormat = new SimpleDateFormat("yyyyMMddHHmmss");
        Date eventDate = dateFormat.parse("2021-01-22 12:34:22");
        System.out.println(dateFormat.format(eventDate));

//结果 ： 20201130220212  

2021年转换成2020年，没有抛出 ParseException 有点费解

看源码解释，默认是lenient的，如果一个格式错误，但是还能继续解析就返回成功，不抛出异常。如果设置成严格setLenient(false)，就会抛出异常

     * <p> By default, parsing is lenient: If the input is not in the form used
     * by this object's format method but can still be parsed as a date, then
     * the parse succeeds.  Clients may insist on strict adherence to the
     * format by calling {@link #setLenient(boolean) setLenient(false)}.

        DateFormat dateFormat = new SimpleDateFormat("yyyyMMddHHmmss");
        dateFormat.setLenient(false);
        Date eventDate = dateFormat.parse("2021-01-22 12:34:22");
        System.out.println(dateFormat.format(eventDate));
//执行结果：

Exception in thread "main" java.text.ParseException: Unparseable date: "2021-01-22 12:34:22"
at java.text.DateFormat.parse(DateFormat.java:366)
at com.idss.test.main(test.java:23)