package com.icil.elsa.test.utils; import java.util.ArrayList; import java.util.Comparator; import java.util.List; import java.util.Map; import java.util.TreeSet; import java.util.stream.Collectors; import org.junit.Test; import groovy.transform.ToString; import lombok.Data; /** * 用 java8 对 list 按照多个字段进行去重 id , message ,orderNO 去重 * 对对象 MilestonesValidTO 按照 field * 参考1:https://blog.csdn.net/robotfive/article/details/89200294 * 参考2:https://blog.csdn.net/weixin_39643007/article/details/90511098 * @throws Exception */ public class GroupBYTest { @Data @ToString public class MilestonesValidTO { private String id; private String message; private String orderNO; private String courierBillNo; private String status; public MilestonesValidTO(String id, String message, String orderNO, String courierBillNo) { super(); this.id = id; this.message = message; this.orderNO = orderNO; this.courierBillNo = courierBillNo; } } /** * 用 java8 对 list 按照多个字段进行去重 id , message ,orderNO 去重 * 对对象 MilestonesValidTO 按照 field * 如果仅仅是去重,推荐使用方式1 * @throws Exception */ /*################# 方式1: 直接重写 comparater 方法 ####################*/ @Test public void testGroupByMutilFiled1() throws Exception { ArrayList<MilestonesValidTO> list = new ArrayList<MilestonesValidTO>(); list.add(new MilestonesValidTO("1","A","sea","2341")); list.add(new MilestonesValidTO("1","A","sea","2341")); list.add(new MilestonesValidTO("3","B","sea","2341")); list.add(new MilestonesValidTO("4","A","sea","2341")); list.add(new MilestonesValidTO("5","C","sea","2341")); List<MilestonesValidTO> lst = list.parallelStream().collect(Collectors.collectingAndThen(Collectors.toCollection( () -> new TreeSet<>(Comparator.comparing(o -> o.getId() + "#" + o.getMessage() + "#" + o.getOrderNO()))), ArrayList<MilestonesValidTO>::new)); lst.forEach(m-> System.err.println(m.toString())); } /** * 用 java8 对 list 按照多个字段进行去重 id , message ,orderNO 去重 * 对对象 MilestonesValidTO 按照 field * 方式2:用于收集,统计,比较合适 * @throws Exception */ /*################# 方式2: Collectors.groupingBy(内嵌groupBy) ####################*/ @Test public void testGroupByMutilFiled2() throws Exception { ArrayList<MilestonesValidTO> list = new ArrayList<MilestonesValidTO>(); list.add(new MilestonesValidTO("1","A","sea","2341")); list.add(new MilestonesValidTO("1","A","sea","2341")); list.add(new MilestonesValidTO("3","B","sea","2341")); list.add(new MilestonesValidTO("4","A","sea","2341")); list.add(new MilestonesValidTO("5","C","sea","2341")); // Map<String, Map<String, Double>> sumCase = statisticalAnalyses.stream() // .collect(Collectors.groupingBy( // StatisticalAnalysis::getCreateTime, // Collectors.groupingBy(StatisticalAnalysis::getHandlingDepartmentName, Collectors.summingDouble(StatisticalAnalysis::getSimplePenaltyAmount)))); Map<String, Map<String, List<MilestonesValidTO>>> collect = list.parallelStream() .collect(Collectors.groupingBy(MilestonesValidTO::getId,Collectors.groupingBy(MilestonesValidTO::getMessage))); collect.forEach((k,v)->{System.err.println("K->"+k+" V-->"+v);}); } }
java8 groupby 对多个字段进行去重, 统计
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转载自www.cnblogs.com/lshan/p/11096289.html
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