Lambda遍历两个List匹配数据
1. 定义一个静态方法
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
|
/** * 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; } |
2. Main方法测试
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
|
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); } |
3. 输出结果
jdk1.8的stream对两个List遍历匹配数据的处理
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
|
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 + '\'' + '}'; } }} |
以上为个人经验，希望能给大家一个参考，也希望大家多多支持服务器之家。
原文链接：https://blog.csdn.net/IT_hejinrong/article/details/89005790
