날짜 계산

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Calendar;

public class Test {
  public static void main(String[] args) {
    try {
      String dateString = "200906090200";

      SimpleDateFormat formatter = new SimpleDateFormat ("yyyyMMddHHmm");
      Date date = formatter.parse(dateString);
      Calendar calendar = Calendar.getInstance();

 

      // 15분전
      calendar.setTime(date);
      calendar.add(Calendar.MINUTE, -15);
      System.out.println(formatter.format(calendar.getTime()));

 

      //  1일전
      calendar.setTime(date);
      calendar.add(Calendar.DAY_OF_MONTH, -1);
      System.out.println(formatter.format(calendar.getTime()));

 

      //  7일전
      calendar.setTime(date);
      calendar.add(Calendar.DAY_OF_MONTH, -7);
      System.out.println(formatter.format(calendar.getTime()));
    } catch(Exception e) {
      e.printStackTrace();
    }
  }
}