Java determines whether a string is a legal date

Determine whether a string like "2018-02-30" is a correct and reasonable date: (Recommended: java video tutorial)

 //假设传入的日期格式是yyyy-MM-dd HH:mm:ss, 也可以传入yyyy-MM-dd，如2018-1-1或者2018-01-01格式
 
    public static boolean isValidDate(String strDate) {
        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        try {
            // 设置lenient为false. 否则SimpleDateFormat会比较宽松地验证日期，比如2018-02-29会被接受，并转换成2018-03-01 
            
            format.setLenient(false);
            Date date = format.parse(strDate);
            
            //判断传入的yyyy年-MM月-dd日 字符串是否为数字
            String[] sArray = strDate.split("-");
            for (String s : sArray) {
                boolean isNum = s.matches("[0-9]+");
                //+表示1个或多个（如"3"或"225"），*表示0个或多个（[0-9]*）（如""或"1"或"22"），?表示0个或1个([0-9]?)(如""或"7")
                if (!isNum) {
                    return false;
                }
            }
        } catch (Exception e) {
            // e.printStackTrace();
            // 如果throw java.text.ParseException或者NullPointerException，就说明格式不对
            return false;
        }
 
        return true;
    }

SimpleDateFormat class

SimpleDateFormat is a concrete class for formatting and parsing dates in a locale-dependent manner, which allows formatting (date → text), parsing ( text → date) and normalization. SimpleDateFormat enables the selection of any user-defined date/time format pattern.

The SimpleDateFormat class mainly has the following three construction methods.

SimpleDateFormat(): Constructs SimpleDateFormat with the default format and default locale.

SimpleDateFormat(String pattern): Constructs SimpleDateF ormat with the specified format and default locale.

SimpleDateFormat(String pattern,Locale locale): Constructs SimpleDateF ormat with the specified format and the specified locale.

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