Java Data Type - 如何获取该日期附近的数据

import java.util.Calendar;
import java.util.Date;

public class Main {

  public static void main(String[] args) {
    System.out.println(round2Day(new Date()));
  }

  public static Date round2Day(Date date) {
    Calendar cal = Calendar.getInstance();
    cal.setTime(date);
    cal.set(Calendar.HOUR_OF_DAY, 0);
    cal.set(Calendar.MINUTE, 0);
    cal.set(Calendar.SECOND, 0);
    cal.set(Calendar.MILLISECOND, 0);
    return cal.getTime();
  }
}