Java Data Type - 如何获取从当前日期起7天前的日期

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

public class Main {
  public static void main(String[] args) {

    DateTimeFormatter format = DateTimeFormatter
        .ofPattern("yyyy-MM-dd'T'HH:mm:ss'Z'");

    LocalDateTime now = LocalDateTime.now();
    LocalDateTime then = now.minusDays(7);

    System.out.println(String.format("Now:  %s\nThen: %s", now.format(format),
        then.format(format)));

  }
}