Java8的Lambda遍历两个List匹配数据方式

/**

      *  通过遍历两个List中按id属性相等的归结到resultList中

      * @param oneList

      * @param twoList

      */

     public static List<Map<Object, Object>> compareListHitData(List<Map<Object, Object>> oneList, List<Map<Object, Object>> twoList) {

         List<Map<Object, Object>> 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).collect(Collectors.toList());

         return resultList;

     }

public static void main(String[] args) {

         List<Map<Object, Object>> oneList = new ArrayList<>();

         Map<Object, Object> oneMap = new HashMap<>();

         oneMap.put( "id" , 111 );

         oneMap.put( "userName" , "何金荣" );

         Map<Object, Object> twoMap = new HashMap<>();

         twoMap.put( "id" , 222 );

         twoMap.put( "userName" , "Hejinrong" );

         oneList.add(oneMap);

         oneList.add(twoMap);

         List<Map<Object, Object>> twoList = new ArrayList<>();

         Map<Object, Object> threeMap = new HashMap<>();

         threeMap.put( "id" , 111 );

         threeMap.put( "userName" , "何金荣" );

         Map<Object, Object> fourMap = new HashMap<>();

         fourMap.put( "id" , 333 );

         fourMap.put( "userName" , "Hejinrong" );

         twoList.add(threeMap);

         twoList.add(fourMap);

         List<Map<Object, Object>> resultList = compareListHitData(oneList, twoList);

         System.out.println(resultList);

     }

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<AwardInfo> prizeRecords = new ArrayList<AwardInfo>( 6 );

         List<StockInfo> stockDTOList = new ArrayList<StockInfo>();

         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<AwardInfo> resultList1 = prizeRecords.stream()

                 .map(map -> stockDTOList.stream()

                         .filter(m -> !Objects.equals(m.getStockNo(), map.getStockNo()))

                         .findFirst().map(m -> {

                             return map;

                         }).orElse( null ))

                 .filter(Objects::nonNull).collect(Collectors.toList());

         /**

          * 求差集：失败结果参考

          * [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'},

          * AwardInfo{userId='null', stockNo='5', thirdStockNo='null'},

          * AwardInfo{userId='null', stockNo='6', thirdStockNo='null'}]

          */

         System.out.println(resultList1.toString());

        /* List<AwardInfo> list2 = prizeRecords.stream()

                 .filter(map -> stockDTOList.stream().anyMatch(map1 -> map.getStockNo().equals(map1.getStockNo())))

                 .forEach(map -> {

                     map.setThirdStockNo(map1.getThirdStockNo());

                 });*/

         List<AwardInfo> resultList2 = prizeRecords.stream().map(m->{

             stockDTOList.stream().filter(m2->Objects.equals(m.getStockNo(), m2.getStockNo()))

                     .forEach(s-> m.setThirdStockNo(s.getThirdStockNo()));

             return m;

         }).collect(Collectors.toList());

         /**

          * stockNo=4,5,6的结果没去掉！

          * [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());

         List<AwardInfo> list3 = prizeRecords.stream()

                 .map(map -> stockDTOList.stream()

                         .filter(m -> Objects.equals(m.getStockNo(), map.getStockNo()))

                         .findFirst().map(m -> {

                             map.setThirdStockNo(m.getThirdStockNo());

                             return map;

                         }).orElse( null ))

                 .filter(Objects::nonNull).collect(Collectors.toList());

         /**

          * stockNo=4,5,6的结果已去掉

          * [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;

         }

         @Override

         public String toString() {

             return "StockInfo{" +

                     "stockNo='" + stockNo + '\ '' +

                     ", stockName='" + stockName + '\ '' +

                     ", 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;

         }

         @Override

         public String toString() {

             return "AwardInfo{" +

                     "userId='" + userId + '\ '' +

                     ", stockNo='" + stockNo + '\ '' +

                     ", thirdStockNo='" + thirdStockNo + '\ '' +

                     '}' ;

         }

     }

}