【Java】list按照元素对象的指定多个字段属性进行排序

介绍一种通用的Java列表排序方法,适用于任意类型的列表元素,支持按照多个属性进行排序,包括数字、字符串、日期等,无需数据库二次查询,提升系统性能。

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ListUtils.java---功能类

import java.lang.reflect.Field;
import java.text.NumberFormat;
import java.util.Date;
import java.util.List;

/**
 * @ Author:yl1794
 * @ Date:2019/7/3 16:51
 *
 * 在数据库中查出来的列表中,往往需要对不同的字段重新排序。 一般的做法都是使用排序的字段,重新到数据库中查询。
 * 如果不到数据库查询,直接在第一次查出来的list中排序,无疑会提高系统的性能。 下面就写一个通用的方法,对list排序,
 *
 * 至少需要满足以下5点:
 *
 * ①.list元素对象类型任意
 * 		---->使用泛型解决
 *
 * ②.可以按照list元素对象的任意多个属性进行排序,即可以同时指定多个属性进行排序
 * 		--->使用java的可变参数解决
 *
 * ③.list元素对象属性的类型可以是数字(byte、short、int、long、float、double等,包括正数、负数、0)、字符串(char、String)、日期(java.util.Date)
 * 		--->对于数字:统一转换为固定长度的字符串解决,比如数字3和123,转换为"003"和"123" ;再比如"-15"和"7"转换为"-015"和"007"
 * 		--->对于日期:可以先把日期转化为long类型的数字,数字的解决方法如上
 *
 * ④.list元素对象的属性可以没有相应的getter和setter方法
 * 		--->可以使用java反射进行获取private和protected修饰的属性值
 *
 * ⑤.list元素对象的对象的每个属性都可以指定是升序还是降序
 * 	  	-->使用2个重写的方法(一个方法满足所有属性都按照升序(降序),另外一个方法满足每个属性都能指定是升序(降序))
 *
 *
 */
public class ListSortUtils {
    /**
     * 对list的元素按照多个属性名称排序,
     * list元素的属性可以是数字(byte、short、int、long、float、double等,支持正数、负数、0)、char、String、java.util.Date
     *
     * @param list list对象
     * @param isAsc true升序,false降序
     * @param sortnameArr list元素的属性名称
     */
    public static <E> void sort(List<E> list, final boolean isAsc, final String... sortnameArr) {
        list.sort((a, b) -> {
            int ret = 0;
            try {
                for (String aSortnameArr : sortnameArr) {
                    ret = ListSortUtils.compareObject(aSortnameArr, isAsc, a, b);
                    if (0 != ret) {
                        break;
                    }
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
            return ret;
        });
    }

    /**
     * 给list的每个属性都指定是升序还是降序
     *
     * @param list list对象
     * @param sortnameArr  参数数组
     * @param typeArr      每个属性对应的升降序数组, true升序,false降序
     */

    public static <E> void sort(List<E> list, final String[] sortnameArr, final boolean[] typeArr) {
        if (sortnameArr.length != typeArr.length) {
            throw new RuntimeException("属性数组元素个数和升降序数组元素个数不相等");
        }
        list.sort((a, b) -> {
            int ret = 0;
            try {
                for (int i = 0; i < sortnameArr.length; i++) {
                    ret = ListSortUtils.compareObject(sortnameArr[i], typeArr[i], a, b);
                    if (0 != ret) {
                        break;
                    }
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
            return ret;
        });
    }

    /**
     * 对2个对象按照指定属性名称进行排序
     *
     * @param sortname 属性名称
     * @param isAsc true升序,false降序
     * @param a
     * @param b
     * @return
     * @throws Exception
     */
    private static <E> int compareObject(final String sortname, final boolean isAsc, E a, E b) throws Exception {
        int ret;
        Object value1 = ListSortUtils.forceGetFieldValue(a, sortname);
        Object value2 = ListSortUtils.forceGetFieldValue(b, sortname);
        String str1 = value1.toString();
        String str2 = value2.toString();
        if (value1 instanceof Number && value2 instanceof Number) {
            int maxlen = Math.max(str1.length(), str2.length());
            str1 = ListSortUtils.addZero2Str((Number) value1, maxlen);
            str2 = ListSortUtils.addZero2Str((Number) value2, maxlen);
        } else if (value1 instanceof Date && value2 instanceof Date) {
            long time1 = ((Date) value1).getTime();
            long time2 = ((Date) value2).getTime();
            int maxlen = Long.toString(Math.max(time1, time2)).length();
            str1 = ListSortUtils.addZero2Str(time1, maxlen);
            str2 = ListSortUtils.addZero2Str(time2, maxlen);
        }
        if (isAsc) {
            ret = str1.compareTo(str2);
        } else {
            ret = str2.compareTo(str1);
        }
        return ret;
    }

    /**
     * 给数字对象按照指定长度在左侧补0.
     *
     * 使用案例: addZero2Str(11,4) 返回 "0011", addZero2Str(-18,6)返回 "-000018"
     *
     * @param numObj 数字对象
     * @param length 指定的长度
     * @return
     */
    private static String addZero2Str(Number numObj, int length) {
        NumberFormat nf = NumberFormat.getInstance();
        // 设置是否使用分组
        nf.setGroupingUsed(false);
        // 设置最大整数位数
        nf.setMaximumIntegerDigits(length);
        // 设置最小整数位数
        nf.setMinimumIntegerDigits(length);
        return nf.format(numObj);
    }

    /**
     * 获取指定对象的指定属性值(去除private,protected的限制)
     *
     * @param obj 属性名称所在的对象
     * @param fieldName 属性名称
     * @return
     * @throws Exception
     */
    private static Object forceGetFieldValue(Object obj, String fieldName) throws Exception {
        // 若是取父类的属性,则可以用obj.getClass().getSuperclass().getDeclaredField()
        Field field = obj.getClass().getDeclaredField(fieldName);
        Object object = null;
        boolean accessible = field.isAccessible();
        if (!accessible) {
            // 如果是private,protected修饰的属性,需要修改为可以访问的
            field.setAccessible(true);
            object = field.get(obj);
            // 还原private,protected属性的访问性质
            field.setAccessible(accessible);
            return object;
        }
        object = field.get(obj);
        return object;
    }
}

 UserInfo.java

package com;
 
import java.text.SimpleDateFormat;
import java.util.Date;
/**
 * 
 * @author yinaibang
 *
 */
public class UserInfo implements java.io.Serializable {
 
	private static final long serialVersionUID = -3522051445403971732L;
 
	private Integer userId;
	private String username;
	private Date birthDate;
	private Integer age;
	private float fRate;
	private char ch;
 
	public Date getBirthDate() {
		return birthDate;
	}
 
	public String getBirthDatestr() {
		SimpleDateFormat formater = new SimpleDateFormat("yyyy-MM-dd");
		return formater.format(getBirthDate());
	}
 
	public UserInfo(Integer userId, String username, Date birthDate, Integer age, float fRate, char ch) {
		super();
		this.userId = userId;
		this.username = username;
		this.birthDate = birthDate;
		this.age = age;
		this.fRate = fRate;
		this.ch = ch;
	}
 
	@Override
	public String toString() {
		return "UserInfo [userId=" + userId + ", \tusername=" + username + ", \tbirthDate=" + getBirthDatestr()
				+ ", \tage=" + age + ", fRate=" + fRate + ", ch=" + ch + "]";
	}
 
}

 Test.java---测试类

package com;
 
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.List;
 
import com.enable.common.utils.ListUtils;
 
/**
 * 
 * @author yinaibang
 *
 */
public class Test {
 
	public static void main(String[] args) throws Exception {
 
		Test testObj = new Test();
 
		List<UserInfo> list = new ArrayList<UserInfo>();
		// public UserInfo(Integer userId, String username, Date birthDate,Integer age, float fRate, char ch)
		SimpleDateFormat formater = new SimpleDateFormat("yyyy-MM-dd");
		UserInfo user1 = new UserInfo(3, "bbb", formater.parse("1980-12-01"), 1, 1.2f, 'a');
		UserInfo user2 = new UserInfo(0, "126", formater.parse("1900-10-11"), 03, -3.6f, 'c');
		UserInfo user3 = new UserInfo(12, "5", formater.parse("1973-08-21"), 15, 9.32f, 'f');
		UserInfo user4 = new UserInfo(465, "1567", formater.parse("2012-01-26"), 20, 12.56f, '0');
		UserInfo user5 = new UserInfo(2006, "&4m", formater.parse("2010-05-08"), 100, 165.32f, '5');
		UserInfo user6 = new UserInfo(5487, "hf67", formater.parse("2016-12-30"), 103, 56.32f, 'm');
		UserInfo user7 = new UserInfo(5487,"jigg", formater.parse("2000-10-16"), 103, 56.32f, 'm');
		UserInfo user8 = new UserInfo(5487, "jigg", formater.parse("1987-07-25"), 103, 56.32f, 'm');
 
		list.add(user1);
		list.add(user2);
		list.add(user3);
		list.add(user4);
		list.add(user5);
		list.add(user6);
		list.add(user7);
		list.add(user8);
 
		System.out.println("\n-------原来序列-------------------");
		testObj.printfUserInfoList(list);
 
		// 按userId升序、username降序、birthDate升序排序
		String [] sortNameArr = {"userId","username","birthDate"};
		boolean [] isAscArr = {true,false,true};
		ListUtils.sort(list,sortNameArr,isAscArr);
		System.out.println("\n--------按按userId升序、username降序、birthDate升序排序(如果userId相同,则按照username降序,如果username相同,则按照birthDate升序)------------------");
		testObj.printfUserInfoList(list);
		
		// 按userId、username、birthDate都升序排序
		ListUtils.sort(list, true, "userId", "username","birthDate");
		System.out.println("\n--------按userId、username、birthDate排序(如果userId相同,则按照username升序,如果username相同,则按照birthDate升序)------------------");
		testObj.printfUserInfoList(list);
 
		// 按userId、username都倒序排序
		ListUtils.sort(list, false, "userId", "username");
		System.out.println("\n--------按userId和username倒序(如果userId相同,则按照username倒序)------------------");
		testObj.printfUserInfoList(list);
 
		// 按username、birthDate都升序排序
		ListUtils.sort(list, true, "username", "birthDate");
		System.out.println("\n---------按username、birthDate升序(如果username相同,则按照birthDate升序)-----------------");
		testObj.printfUserInfoList(list);
 
		// 按birthDate倒序排序
		ListUtils.sort(list, false, "birthDate");
		System.out.println("\n---------按birthDate倒序-----------------");
		testObj.printfUserInfoList(list);
 
		// 按fRate升序排序
		ListUtils.sort(list, true, "fRate");
		System.out.println("\n---------按fRate升序-----------------");
		testObj.printfUserInfoList(list);
 
		// 按ch倒序排序
		ListUtils.sort(list, false, "ch");
		System.out.println("\n---------按ch倒序-----------------");
		testObj.printfUserInfoList(list);
 
	}
 
	private void printfUserInfoList(List<UserInfo> list) {
		for (UserInfo user : list) {
			System.out.println(user.toString());
		}
	}
}

运行结果

-------原来序列-------------------
UserInfo [userId=3, 	username=bbb, 	birthDate=1980-12-01, 	age=1, fRate=1.2, ch=a]
UserInfo [userId=0, 	username=126, 	birthDate=1900-10-11, 	age=3, fRate=-3.6, ch=c]
UserInfo [userId=12, 	username=5, 	birthDate=1973-08-21, 	age=15, fRate=9.32, ch=f]
UserInfo [userId=465, 	username=1567, 	birthDate=2012-01-26, 	age=20, fRate=12.56, ch=0]
UserInfo [userId=2006, 	username=&4m, 	birthDate=2010-05-08, 	age=100, fRate=165.32, ch=5]
UserInfo [userId=5487, 	username=hf67, 	birthDate=2016-12-30, 	age=103, fRate=56.32, ch=m]
UserInfo [userId=5487, 	username=jigg, 	birthDate=2000-10-16, 	age=103, fRate=56.32, ch=m]
UserInfo [userId=5487, 	username=jigg, 	birthDate=1987-07-25, 	age=103, fRate=56.32, ch=m]
 
--------按按userId升序、username降序、birthDate升序排序(如果userId相同,则按照username降序,如果username相同,则按照birthDate升序)------------------
UserInfo [userId=0, 	username=126, 	birthDate=1900-10-11, 	age=3, fRate=-3.6, ch=c]
UserInfo [userId=3, 	username=bbb, 	birthDate=1980-12-01, 	age=1, fRate=1.2, ch=a]
UserInfo [userId=12, 	username=5, 	birthDate=1973-08-21, 	age=15, fRate=9.32, ch=f]
UserInfo [userId=465, 	username=1567, 	birthDate=2012-01-26, 	age=20, fRate=12.56, ch=0]
UserInfo [userId=2006, 	username=&4m, 	birthDate=2010-05-08, 	age=100, fRate=165.32, ch=5]
UserInfo [userId=5487, 	username=jigg, 	birthDate=1987-07-25, 	age=103, fRate=56.32, ch=m]
UserInfo [userId=5487, 	username=jigg, 	birthDate=2000-10-16, 	age=103, fRate=56.32, ch=m]
UserInfo [userId=5487, 	username=hf67, 	birthDate=2016-12-30, 	age=103, fRate=56.32, ch=m]
 
--------按userId、username、birthDate排序(如果userId相同,则按照username升序,如果username相同,则按照birthDate升序)------------------
UserInfo [userId=0, 	username=126, 	birthDate=1900-10-11, 	age=3, fRate=-3.6, ch=c]
UserInfo [userId=3, 	username=bbb, 	birthDate=1980-12-01, 	age=1, fRate=1.2, ch=a]
UserInfo [userId=12, 	username=5, 	birthDate=1973-08-21, 	age=15, fRate=9.32, ch=f]
UserInfo [userId=465, 	username=1567, 	birthDate=2012-01-26, 	age=20, fRate=12.56, ch=0]
UserInfo [userId=2006, 	username=&4m, 	birthDate=2010-05-08, 	age=100, fRate=165.32, ch=5]
UserInfo [userId=5487, 	username=hf67, 	birthDate=2016-12-30, 	age=103, fRate=56.32, ch=m]
UserInfo [userId=5487, 	username=jigg, 	birthDate=1987-07-25, 	age=103, fRate=56.32, ch=m]
UserInfo [userId=5487, 	username=jigg, 	birthDate=2000-10-16, 	age=103, fRate=56.32, ch=m]
 
--------按userId和username倒序(如果userId相同,则按照username倒序)------------------
UserInfo [userId=5487, 	username=jigg, 	birthDate=1987-07-25, 	age=103, fRate=56.32, ch=m]
UserInfo [userId=5487, 	username=jigg, 	birthDate=2000-10-16, 	age=103, fRate=56.32, ch=m]
UserInfo [userId=5487, 	username=hf67, 	birthDate=2016-12-30, 	age=103, fRate=56.32, ch=m]
UserInfo [userId=2006, 	username=&4m, 	birthDate=2010-05-08, 	age=100, fRate=165.32, ch=5]
UserInfo [userId=465, 	username=1567, 	birthDate=2012-01-26, 	age=20, fRate=12.56, ch=0]
UserInfo [userId=12, 	username=5, 	birthDate=1973-08-21, 	age=15, fRate=9.32, ch=f]
UserInfo [userId=3, 	username=bbb, 	birthDate=1980-12-01, 	age=1, fRate=1.2, ch=a]
UserInfo [userId=0, 	username=126, 	birthDate=1900-10-11, 	age=3, fRate=-3.6, ch=c]
 
---------按username、birthDate升序(如果username相同,则按照birthDate升序)-----------------
UserInfo [userId=2006, 	username=&4m, 	birthDate=2010-05-08, 	age=100, fRate=165.32, ch=5]
UserInfo [userId=0, 	username=126, 	birthDate=1900-10-11, 	age=3, fRate=-3.6, ch=c]
UserInfo [userId=465, 	username=1567, 	birthDate=2012-01-26, 	age=20, fRate=12.56, ch=0]
UserInfo [userId=12, 	username=5, 	birthDate=1973-08-21, 	age=15, fRate=9.32, ch=f]
UserInfo [userId=3, 	username=bbb, 	birthDate=1980-12-01, 	age=1, fRate=1.2, ch=a]
UserInfo [userId=5487, 	username=hf67, 	birthDate=2016-12-30, 	age=103, fRate=56.32, ch=m]
UserInfo [userId=5487, 	username=jigg, 	birthDate=1987-07-25, 	age=103, fRate=56.32, ch=m]
UserInfo [userId=5487, 	username=jigg, 	birthDate=2000-10-16, 	age=103, fRate=56.32, ch=m]
 
---------按birthDate倒序-----------------
UserInfo [userId=5487, 	username=hf67, 	birthDate=2016-12-30, 	age=103, fRate=56.32, ch=m]
UserInfo [userId=465, 	username=1567, 	birthDate=2012-01-26, 	age=20, fRate=12.56, ch=0]
UserInfo [userId=2006, 	username=&4m, 	birthDate=2010-05-08, 	age=100, fRate=165.32, ch=5]
UserInfo [userId=5487, 	username=jigg, 	birthDate=2000-10-16, 	age=103, fRate=56.32, ch=m]
UserInfo [userId=5487, 	username=jigg, 	birthDate=1987-07-25, 	age=103, fRate=56.32, ch=m]
UserInfo [userId=3, 	username=bbb, 	birthDate=1980-12-01, 	age=1, fRate=1.2, ch=a]
UserInfo [userId=12, 	username=5, 	birthDate=1973-08-21, 	age=15, fRate=9.32, ch=f]
UserInfo [userId=0, 	username=126, 	birthDate=1900-10-11, 	age=3, fRate=-3.6, ch=c]
 
---------按fRate升序-----------------
UserInfo [userId=0, 	username=126, 	birthDate=1900-10-11, 	age=3, fRate=-3.6, ch=c]
UserInfo [userId=3, 	username=bbb, 	birthDate=1980-12-01, 	age=1, fRate=1.2, ch=a]
UserInfo [userId=12, 	username=5, 	birthDate=1973-08-21, 	age=15, fRate=9.32, ch=f]
UserInfo [userId=465, 	username=1567, 	birthDate=2012-01-26, 	age=20, fRate=12.56, ch=0]
UserInfo [userId=5487, 	username=hf67, 	birthDate=2016-12-30, 	age=103, fRate=56.32, ch=m]
UserInfo [userId=5487, 	username=jigg, 	birthDate=2000-10-16, 	age=103, fRate=56.32, ch=m]
UserInfo [userId=5487, 	username=jigg, 	birthDate=1987-07-25, 	age=103, fRate=56.32, ch=m]
UserInfo [userId=2006, 	username=&4m, 	birthDate=2010-05-08, 	age=100, fRate=165.32, ch=5]
 
---------按ch倒序-----------------
UserInfo [userId=5487, 	username=hf67, 	birthDate=2016-12-30, 	age=103, fRate=56.32, ch=m]
UserInfo [userId=5487, 	username=jigg, 	birthDate=2000-10-16, 	age=103, fRate=56.32, ch=m]
UserInfo [userId=5487, 	username=jigg, 	birthDate=1987-07-25, 	age=103, fRate=56.32, ch=m]
UserInfo [userId=12, 	username=5, 	birthDate=1973-08-21, 	age=15, fRate=9.32, ch=f]
UserInfo [userId=0, 	username=126, 	birthDate=1900-10-11, 	age=3, fRate=-3.6, ch=c]
UserInfo [userId=3, 	username=bbb, 	birthDate=1980-12-01, 	age=1, fRate=1.2, ch=a]
UserInfo [userId=2006, 	username=&4m, 	birthDate=2010-05-08, 	age=100, fRate=165.32, ch=5]
UserInfo [userId=465, 	username=1567, 	birthDate=2012-01-26, 	age=20, fRate=12.56, ch=0]

本文转载自:https://blog.youkuaiyun.com/enable1234___/article/details/53224740,有部分修改

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