How to use Lambda to traverse two List matching data in Java8

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Lambda traverses two List matching data 1. Define a static method / * by traversing two List that are equal by id attribute to resultList * @ param oneList * @ param twoList * / public static List compareListHitData (List oneList, List twoList) {List resultList = oneList.stream (). Map (map-> twoList.stream () .filter (m-> Objects.equals (m.get ("id")) Map.get ("id")) .findFirst () .map (m-> {map.putAll (m)) Return map;}) .orElse (null) .filter (Objects::nonNull) .filter (Collectors.toList ()); return resultList;} 2. Main method testing public static void main (String [] args) {List oneList = new ArrayList (); Map oneMap = new HashMap (); oneMap.put ("id", 111) OneMap.put ("userName", "he Jinrong"); Map twoMap = new HashMap (); twoMap.put ("id", 2222); twoMap.put ("userName", "Hejinrong"); oneList.add (oneMap); oneList.add (twoMap); List twoList = new ArrayList (); Map threeMap = new HashMap (); threeMap.put ("id", 111) ThreeMap.put ("userName", "he Jinrong"); Map fourMap = new HashMap (); fourMap.put ("id", 333); fourMap.put ("userName", "Hejinrong"); twoList.add (threeMap); twoList.add (fourMap); List resultList = compareListHitData (oneList, twoList); System.out.println (resultList);} 3. Output result

Jdk1.8 's stream processing of two List traversal matching data import java.util.ArrayList;import java.util.List;import java.util.Objects;import java.util.stream.Collectors; public class testStream {public static void main (String [] args) {List prizeRecords = new ArrayList (6); List stockDTOList = new ArrayList (); for (int I = 0; I

< 6; i++) { AwardInfo AwardInfo = new AwardInfo(); AwardInfo.setStockNo((i+1)+""); prizeRecords.add(AwardInfo); } for (int i = 0; i < 3; i++) { StockInfo stockDTO = new StockInfo(); stockDTO.setStockNo((i+1)+""); stockDTO.setThirdStockNo("third"+(i+1)); stockDTOList.add(stockDTO); } StockInfo stockDTO1 = new StockInfo(); stockDTO1.setStockNo((44)+""); stockDTO1.setThirdStockNo("third"+44); stockDTOList.add(stockDTO1); StockInfo stockDTO2 = new StockInfo(); stockDTO2.setStockNo((55)+""); stockDTO2.setThirdStockNo("third"+55); stockDTOList.add(stockDTO2); //prizeRecords与stockDTOList求差集 List resultList1 = prizeRecords.stream() .map(map ->

/ * difference set: refer to * [AwardInfo {userId='null', stockNo='1', thirdStockNo='null'}, * AwardInfo {userId='null', stockNo='2', thirdStockNo='null'}, * AwardInfo {userId='null', stockNo='3', thirdStockNo='null'}, * AwardInfo {userId='null', stockNo='4', thirdStockNo='null'} for failure result * AwardInfo {userId='null', stockNo='5', thirdStockNo='null'}, * AwardInfo {userId='null', stockNo='6', thirdStockNo='null'}] * / System.out.println (resultList1.toString ()) * / List resultList2 = prizeRecords.stream (). Map (m-> {stockDTOList.stream (). Filter (M2-> Objects.equals (m.getStockNo (), m2.getStockNo () .forEach (s-> m.setThirdStockNo (s.getThirdStockNo (); return m;}) .destroy (Collectors.toList ()); / * * the result of stockNo=4,5,6 is not removed! * [AwardInfo {userId='null', stockNo='1', thirdStockNo='third1'}, * AwardInfo {userId='null', stockNo='2', thirdStockNo='third2'}, * AwardInfo {userId='null', stockNo='3', thirdStockNo='third3'}, * AwardInfo {userId='null', stockNo='4', thirdStockNo='null'}, * AwardInfo {userId='null', stockNo='5', thirdStockNo='null'}, * AwardInfo {userId='null' StockNo='6', thirdStockNo='null'}] * / System.out.println (resultList2.toString ()) }) .orElse (null)) .filter (Objects::nonNull) .filter (Collectors.toList ()) The result of / * stockNo=4,5,6 has been removed * [AwardInfo {userId='null', stockNo='1', thirdStockNo='third1'}, * AwardInfo {userId='null', stockNo='2', thirdStockNo='third2'}, * AwardInfo {userId='null', stockNo='3', thirdStockNo='third3'}] * / System.out.println (list3.toString ()) } static class StockInfo {private String stockNo; private String stockName; private String thirdStockNo; public String getStockNo () {return stockNo;} public void setStockNo (String stockNo) {this.stockNo = stockNo;} public String getStockName () {return stockName } public void setStockName (String stockName) {this.stockName = stockName;} public String getThirdStockNo () {return thirdStockNo;} public void setThirdStockNo (String thirdStockNo) {this.thirdStockNo = thirdStockNo }} static class AwardInfo {private String userId; private String stockNo; private String thirdStockNo; public String getUserId () {return userId;} public void setUserId (String userId) {this.userId = userId;} public String getStockNo () {return stockNo } public void setStockNo (String stockNo) {this.stockNo = stockNo;} public String getThirdStockNo () {return thirdStockNo;} public void setThirdStockNo (String thirdStockNo) {this.thirdStockNo = thirdStockNo } the above is about the content of this article on "how to use Lambda to traverse two List matching data in Java8". I believe we all have some understanding. I hope the content shared by the editor will be helpful to you. If you want to know more about the relevant knowledge, please follow the industry information channel.