Java 8 LocalDateTime convert date format:

input: 20191024194947087 : length 17

substring: 20191024194947: length 14

output: 2019/04/24 19:49:47

    @Test
    public void dateTimeFormat() {
        String input = "20191024194947087";
        DateTimeFormatter f = DateTimeFormatter.ofPattern("yyyyMMddHHmmss");
        LocalDateTime ldt = LocalDateTime.parse(input.substring(0, 14), f);
        String format = ldt.format(DateTimeFormatter.ofPattern("yyyy/MM/dd HH:mm:ss"));
        Assert.assertEquals("2019/10/24 19:49:47", format);
    }
    // result
    // 2019/10/24 19:49:47

 

input: 20191024194947087 : length 17

substring: 20191024194947 : length 14

output: 2019/10/24

    @Test
    public void dateFormat() {
        String input = "20191024194947087";
        DateTimeFormatter f = DateTimeFormatter.ofPattern("yyyyMMddHHmmss");
        LocalDateTime ldt = LocalDateTime.parse(input.substring(0, 14), f);
        String format = ldt.format(DateTimeFormatter.ofPattern("yyyy/MM/dd"));
        Assert.assertEquals("2019/10/24", format);
    }
    // result
    // 2019/10/24

 

---

2020.04.17 -> format (yyyy-MM-dd) => 2020-04-17

2020.04.17 -> format (yyyy/MM/dd) => 2020/04/17

    private String convertDateFormat(String date, String format) {
        return LocalDate.parse(date, DateTimeFormatter.ofPattern("yyyy.MM.dd")).format(DateTimeFormatter.ofPattern(format));
    }

---

date: 2020-04-17

before: yyyy-MM-dd

after: yyyyMMdd000000 

 

result: 20200417000000

    private String convertDateFormat(String date, String before, String after) {
        return LocalDate.parse(date, DateTimeFormatter.ofPattern(before)).format(DateTimeFormatter.ofPattern(after));
    }