DateTimeFormatter Demo

import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;

public class DateFormatter {
    public static void main(String[] args) {
        //DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern("yyyy/mm/dd-hh:mm:ss");
        //2018/06/15-04:06:13
        //DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern("yyyy/MM/dd-hh:mm:ss");
        //2018/10/15-04:06:49
        DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern("yyyy/MM/dd-HH:mm:ss");
        //2018/10/15-16:07:40
        DateTimeFormatter timestampFormatter = DateTimeFormatter.ofPattern("yyyyMMddHHmmss");
        //20181015161416
        LocalDateTime now = LocalDateTime.now();
        String date = dateTimeFormatter.format(now);
        String timestamp = timestampFormatter.format(now);
        System.out.println(date);
        System.out.println(timestamp);
    }
}

So MM stands for month, and mm stands for minute.
HH stands for hour in 24-hour clock, hh stands for hour in 12-hour clock.
Generate a timestamp? Pattern yyyyMMddHHmmss will do.