日期格式化问题

Posted 2020-11-25 cstdio1

代码如下

sdf.format(date)将日期类型转为指定格式字符串

sdf.parse(str)将字符串类型转为Date类型

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Collections;
import java.util.Comparator;
import java.util.Date;
import java.util.LinkedList;
import java.util.List;

    public class test {
    
    public static void main(String[] args) throws ParseException {
    List <Date> dates = new LinkedList<>();
    SimpleDateFormat sdf= new SimpleDateFormat("yyyy-mm-dd");
    
    String s1 = "2019-08-10 22:18:22";
    String s2 = "2018-08-10 22:18:22";
    String s3 = "2017-08-10 22:19:22";
    String s4 = "2025-01-10 22:19:22";
    String []s={s1,s2,s3,s4};
    //转日期
    dates.add(sdf.parse(s1));
    dates.add(sdf.parse(s2));
    dates.add(sdf.parse(s3));
    dates.add(sdf.parse(s4));
    //转日期，sdf.parse
    //转格式化，sdf.format
    //集合排序
//  Collections.sort(dates,(l,r)->{
//      return sdf.format(r).compareTo(sdf.format(l));
//  });
    
    
    //普通数组排序
//  Arrays.sort(s,(l,r)->{
//      return l.compareToIgnoreCase(r);
//  });
    
    //集合排序，直接倒置
    Collections.sort(dates,Comparator.reverseOrder());
    for(Date date:dates){
        System.out.println(sdf.format(date));
    }
    
    System.out.println(sdf.format(dates.get(0)).getClass());
    
//  dates.forEach(x->System.out.println(sdf.format(x)));
    

}

}

输出