java list 多条件排序_List＜Map＞ 多字段排序
package com.example.test;
import com.beust.jcommander.internal.Lists;
import com.beust.jcommander.internal.Maps;
import com.example.utils.DateUtil;
import org.junit.Test;
import java.util.*;
import java.util.stream.Collectors;
/**
* @author
* @Description
* @create 2020-07-29 17:58
*/
public class CommonTest {
class PojoTest {
private int num;
private Date date;
public PojoTest(int num, Date date) {
this.num = num;
this.date = date;
}
public int getNum() {
return num;
}
public void setNum(int num) {
this.num = num;
}
public Date getDate() {
return date;
}
public void setDate(Date date) {
this.date = date;
}
@Override
public String toString() {
return "PojoTest{" +
"num=" + num +
", date=" + date +
'}';
}
}
@Test
public void test() {
List pojos = Lists.newArrayList(
new PojoTest(10, DateUtil.formatStringToDate("2020-07-30", "yyyy-MM-dd")),
new PojoTest(10, DateUtil.formatStringToDate("2020-07-29", "yyyy-MM-dd")),
new PojoTest(16, DateUtil.formatStringToDate("2020-07-28", "yyyy-MM-dd")),
new PojoTest(16, DateUtil.formatStringToDate("2020-07-30", "yyyy-MM-dd")),
new PojoTest(20, DateUtil.formatStringToDate("2020-07-31", "yyyy-MM-dd"))
);
System.err.println("===================0======================");
// stream.sorted 类中单个字段排序
List pojoTests = pojos.stream().sorted(Comparator.comparing(PojoTest::getDate)).collect(Collectors.toList());
pojoTests.forEach(System.err::println);
System.err.println("===================1======================");
// stream.sorted 类中单个字段排序
pojoTests = pojos.stream().sorted(Comparator.comparing(PojoTest::getNum)).collect(Collectors.toList());
pojoTests.forEach(System.err::println);
System.err.println("===================2======================");
// stream.sorted 类中多个字段排序
pojoTests = pojos.stream().sorted(Comparator.comparing(PojoTest::getNum).thenComparing(PojoTest::getDate, Comparator.reverseOrder())).collect(Collectors.toList());
pojoTests.forEach(System.err::println);
System.err.println("===================3======================");
// list.sort 类中多个字段排序
pojos.sort(Comparator.comparing(PojoTest::getNum).thenComparing(PojoTest::getDate, Comparator.reverseOrder()));
pojos.forEach(System.err::println);
System.err.println("===================4======================");
List maps = Lists.newArrayList(
Maps.newHashMap("aa", 10, "bb", DateUtil.formatStringToDate("2020-07-30", "yyyy-MM-dd")),
Maps.newHashMap("aa", 10, "bb", DateUtil.formatStringToDate("2020-07-29", "yyyy-MM-dd")),
Maps.newHashMap("aa", 16, "bb", DateUtil.formatStringToDate("2020-07-28", "yyyy-MM-dd")),
Maps.newHashMap("aa", 16, "bb", DateUtil.formatStringToDate("2020-07-30", "yyyy-MM-dd")),
Maps.newHashMap("aa", 20, "bb", DateUtil.formatStringToDate("2020-07-31", "yyyy-MM-dd"))
);
// List 使用sorted排序时，单个字段排序没有问题, 但是使用thenComparing排序多个字段就会出现问题，似乎是无法确认类型的问题，详细原因我也不是太清楚，有大佬知道的话麻烦可以在评论里说下，谢谢
maps = maps.stream().sorted(Comparator.comparing(a -> Long.parseLong(a.get("aa") + ""))).collect(Collectors.toList());
maps.forEach(System.err::println);
System.err.println("===================5======================");
// maps = maps.stream().sorted(Comparator.comparing(a -> Long.parseLong(a.get("aa") + "")).thenComparing(Comparator.comparing(a -> (Date) a.get("bb"), Comparator.reverseOrder()))).collect(Collectors.toList());
// 上面那种方式没法排序，但是直接使用list的sort排序却是可以的
Comparator aa = Comparator.comparing(a -> Long.parseLong(a.get("aa") + ""));
Comparator bb = Comparator.comparing(a -> (Date) a.get("bb"), Comparator.reverseOrder());
maps.sort(aa.thenComparing(bb));
maps.forEach(System.err::println);
}
}