Java 中排序日期

2025年5月13日 | 阅读 4 分钟

Collection 类中 Comparator 机制的一部分 sort() 方法，用于按降序对数据进行排序。

如果我们希望在通用场景下实现此目标，同时考虑要排序的对象是用户定义的边界条件，我们可以使用 Comparator 接口。下面将讨论这两种方法，其中用户定义的类型也用于生成对象。

在 Java 中，有多种方法可以按日期对 ArrayList 进行排序。可以通过使用 Comparable<> 接口或 Collections.sort() 方法来完成；我们可以使用以下任何一种方法。

Comparator 接口
sort() 方法

1. Comparator 接口

使用 Comparator 接口按日期对 ArrayList 元素进行排序的 Java 程序。

SortDate1.java

import java.util.*;
class DateI
{
	String date; 
	/* Constructor */
	DateI(String date)
	{
		/* This keyword is used to refer current object */
		this.date = date;
	}
}
class sortCompare implements Comparator<DateI> 
{
	// Method of this class
	@Override
	public int compare(DateI a, DateI b)
	{
		/* Returns sorted data in ascending order */
		return a.date.compareTo(b.date);
	}
}
public class SortDate1 
{
	/* Driver Code */
	public static void main(String args[])
	{
		ArrayList<DateI> dates = new ArrayList<>();
		/* Adding data to the ArrayList */
		dates.add(new DateI("2021-05-14"));
		dates.add(new DateI("2019-06-24"));
		dates.add(new DateI("1998-02-20"));
		dates.add(new DateI("1999-04-26"));
		/* Sort the ArrayList with Collections.sort() method */
		Collections.sort(dates, new sortCompare());
		System.out.println("Dates sorted in Ascending Order");
		for (DateI d : dates) 
		{
			System.out.println(d.date);
		}
	}
}

输出

Dates sorted in Ascending Order
1998-02-20
1999-04-26
2019-06-24
2021-05-14

让我们看另一个例子。

SortDate2.java

import java.util.*;
class DateI 
{
	String date;
	/* Constructor */
	DateI(String date)
	{
        /* This keyword is used to refer current object */
		this.date = date;
	}
}
class sortCompare implements Comparator<DateI> 
{
	@Override
	// Method of this class
	public int compare(DateI a, DateI b)
	{
		/* Returns sorted data in Descending order */
		return b.date.compareTo(a.date);
	}
}
public class SortDate2 {
	/* Driver Code */
	public static void main(String args[])
	{
		ArrayList<DateI> dates = new ArrayList<>();
		/* Adding data to the ArrayList */
		dates.add(new DateI("2021-05-14"));
		dates.add(new DateI("2019-06-24"));
		dates.add(new DateI("1998-02-20"));
		dates.add(new DateI("1999-04-26"));
        /* Sort the ArrayList with Collections.sort() method */
		Collections.sort(dates, new sortCompare());
		System.out.println("Dates sorted in Descending Order");
    
		for (DateI d : dates) 
		{
			System.out.println(d.date);
		}
	}
}

输出

Dates sorted in Descending Order
2021-05-14
2019-06-24
1999-04-26
1998-02-20

2. sort() 方法

使用 Collections.sort() 方法按日期对 ArrayList 元素进行排序的 Java 程序

SortDate3.java

import java.util.*;
public class SortDate3 
{
	/* Driver Code */
	public static void main(String[] args)
	{
		/* Creating an ArrayList of String to store the Dates */
		ArrayList<String> datesList = new ArrayList<>();
		/* Adding date to ArrayList using standard add() method */
		datesList.add("2020-03-25");
		datesList.add("2019-01-27");
		datesList.add("2020-03-26");
		datesList.add("2020-02-26");
		// Display message only
		System.out.println(
			"Dates Object before sorting : ");
		/* Iterating in the ArrayList using for each loop */
		for (String dates : datesList) {
			// Printing the data from the list
			System.out.println(dates);
		}
		/* Sorting the ArrayList using Collections.sort() method */
		Collections.sort(datesList);
		// Display message only
		System.out.println("Dates Object after sorting : ");
		/* Iterating in the ArrayList using for-each loop */
		for(String dates : datesList) {
			/* Printing the data from the list */
			System.out.println(dates);
		}
	}
}

输出

Dates Object before sorting: 
2020-03-25
2019-01-27
2020-03-26
2020-02-26
Dates Object after sorting: 
2019-01-27
2020-02-26
2020-03-25
2020-03-26

SortDate4.java

import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
 
public class SortDate4
{
/* Driver Code */
public static void main(String[] args) 
{
//java 8
sortDateTimeObject();
sortDateTimeText();
}
 
private static void sortDateTimeObject() {
List<LocalDateTime>dateTimeList=new ArrayList<LocalDateTime>();
dateTimeList.add(LocalDateTime.of(2012, 05, 12, 5, 16));
dateTimeList.add(LocalDateTime.of(2014, 03, 23, 11, 26));
dateTimeList.add(LocalDateTime.of(2011, 02, 13, 9, 36));
dateTimeList.add(LocalDateTime.of(2013, 11, 12, 5, 16));
dateTimeList.add(LocalDateTime.of(2017, 8, 11, 21, 26));
dateTimeList.add(LocalDateTime.of(2016, 9, 05, 19, 36));
 
DateTimeFormatter dateTimeFormatter = DateTimeFormatter
                .ofPattern("MM/dd/yyyy '@'hh:mm a");
System.out.println("---> Date & Time Object List Before Sort (MM/dd/yyyy '@'hh:mm a)");
for(LocalDateTime dateTime:dateTimeList)
{
System.out.println(dateTime.format(dateTimeFormatter));
}
// LocalDateTime  internally having Comparable interface no need additional Comparator
Collections.sort(dateTimeList);
 
System.out.println("---> Date & Time Object List After Sort (MM/dd/yyyy '@'hh:mm a)");
for(LocalDateTime dateTime:dateTimeList)
{
System.out.println(dateTime.format(dateTimeFormatter));
}
 
}
 
private static void sortDateTimeText()
{
List<String>dateStrList=new ArrayList<String>();
// MM/dd/yyyy '@'hh:mm a
dateStrList.add("01/21/2014 @03:13 PM");
dateStrList.add("01/21/2011 @04:37 PM");
dateStrList.add("01/21/2012 @10:41 AM");
dateStrList.add("01/21/2013 @10:48 AM");
dateStrList.add("01/22/2015 @06:16 AM");
dateStrList.add("01/22/2013 @06:19 AM");
dateStrList.add("01/21/2018 @05:19 PM");
dateStrList.add("01/21/2013 @05:19 PM");
 
System.out.println("---> Date & Time List Before Sort (MM/dd/yyyy '@'hh:mm a)");
for(String dateStr:dateStrList)
System.out.println(dateStr);
 
//Sort String Date
Collections.sort(dateStrList, new Comparator<String>() {
DateFormat f = new SimpleDateFormat("MM/dd/yyyy '@'hh:mm a");
@Override
public int compare(String o1, String o2) {
try {
  return f.parse(o1).compareTo(f.parse(o2));
    } catch (ParseException e) {
      throw new IllegalArgumentException(e);
    }
}
});
 
System.out.println("---> Date & Time List After Sort (MM/dd/yyyy '@'hh:mm a)");
for(String dateStr:dateStrList)
System.out.println(dateStr);
 }
}

输出

---> Date & Time Object List Before Sort (MM/dd/yyyy '@'hh:mm a)
05/12/2012 @05:16 AM
03/23/2014 @11:26 AM
02/13/2011 @09:36 AM
11/12/2013 @05:16 AM
08/11/2017 @09:26 PM
09/05/2016 @07:36 PM
---> Date & Time Object List After Sort (MM/dd/yyyy '@'hh:mm a)
02/13/2011 @09:36 AM
05/12/2012 @05:16 AM
11/12/2013 @05:16 AM
03/23/2014 @11:26 AM
09/05/2016 @07:36 PM
08/11/2017 @09:26 PM
---> Date & Time List Before Sort (MM/dd/yyyy '@'hh:mm a)
01/21/2014 @03:13 PM
01/21/2011 @04:37 PM
01/21/2012 @10:41 AM
01/21/2013 @10:48 AM
01/22/2015 @06:16 AM
01/22/2013 @06:19 AM
01/21/2018 @05:19 PM
01/21/2013 @05:19 PM
---> Date & Time List After Sort (MM/dd/yyyy '@'hh:mm a)
01/21/2011 @04:37 PM
01/21/2012 @10:41 AM
01/21/2013 @10:48 AM
01/21/2013 @05:19 PM
01/22/2013 @06:19 AM
01/21/2014 @03:13 PM
01/22/2015 @06:16 AM
01/21/2018 @05:19 PM

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Java 中排序日期

1. Comparator 接口

2. sort() 方法

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1. Comparator 接口

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