一、问题背景
在java的开发过程中，我们往往也需要用对象进行分组进行处理，如何对List进行分组呢？以下我们简单高效的实现分组
二、问题解决
1 //以下WarehouseDeliveryTimeVO的列表中对其属性logisticsModel(物流模式)进行分组，new String[]{}可以按照多个属性进行分组，allTimeVO为其对象列表
2 Map<String,List<WarehouseDeliveryTimeVO>> logisticsModelGoodsMap = Hashlize.hashlizeObjects( allTimeVO,new HashKeyAdapter(new String[]{"logisticsModel"}));
3 //通过迭代可以获取分组后的结果
4 for(String key : logisticsModelGoodsMap.keySet()){
5 List<WarehouseDeliveryTimeVO> timeVO = logisticsModelGoodsMap.get(key);
6 //以下是获取分组后列表的其他业务操作
7 //checkTimeCross(timeVO);
8 }
当然我们也可以按照多个对象的属性进行分组，方法就是在 new String[]{"属性一","属性二"}，即可按照所设置的两个属性进行分组，简单，高效。
用作公共类 超棒！！
涉及的接口 IHashKey
1 package com.xxxx.dsc.application.utils;
2
3 public interface IHashKey {
4 String getKey(Object var1);
5 }接口 ICombine
1 package com.xxxx.dsc.application.utils;
2
3 public interface ICombine {
4 Object combine(Object var1, Object var2);
5 }类 HashKeyAdapter
1 package com.xxxx.dsc.application.utils;
2
3 import java.lang.reflect.InvocationTargetException;
4 import org.apache.commons.beanutils.PropertyUtils;
5 import org.apache.commons.lang3.StringUtils;
6
7 public class HashKeyAdapter implements IHashKey {
8 String[] m_KeyFields;
9 static final String m_FixKey = "FIXKEY#$@";
10
11 public HashKeyAdapter(String[] keyFields) {
12 this.m_KeyFields = keyFields;
13 }
14
15 public String getKey(Object o) {
16 if (this.m_KeyFields != null && this.m_KeyFields.length != 0) {
17 String key = "";
18
19 for(int i = 0; i < this.m_KeyFields.length; ++i) {
20 try {
21 if (StringUtils.isNotEmpty("" + PropertyUtils.getSimpleProperty(o, this.m_KeyFields[i]))) {
22 Object v = PropertyUtils.getSimpleProperty(o, this.m_KeyFields[i]);
23 key = key + (v == null ? "" : v + "");
24 }
25 } catch (IllegalAccessException var5) {
26 throw new RuntimeException(var5.getMessage(), var5);
27 } catch (InvocationTargetException var6) {
28 throw new RuntimeException(var6.getMessage(), var6);
29 } catch (NoSuchMethodException var7) {
30 throw new RuntimeException(var7.getMessage(), var7);
31 }
32 }
33
34 return key;
35 } else {
36 return "FIXKEY#$@";
37 }
38 }
39 }类 Hashlize
1 //
2 // 分组 返回Map
3 // 4
5
6 package com.xxxx.dsc.application.utils;
7
8 import java.util.ArrayList;
9 import java.util.HashMap;
10 import java.util.HashSet;
11 import java.util.LinkedHashMap;
12 import java.util.List;
13 import java.util.Set;
14 import org.apache.commons.collections.CollectionUtils;
15
16 public class Hashlize {
17 public Hashlize() {
18 }
19
20 public static HashMap hashlizeObjects(Object[] objs, IHashKey iHashKey) {
21 if (objs != null && objs.length != 0) {
22 if (iHashKey == null) {
23 throw new RuntimeException("iHashKey cann't be null");
24 } else {
25 HashMap result = new HashMap();
26
27 for(int i = 0; i < objs.length; ++i) {
28 String key = iHashKey.getKey(objs[i]);
29 ArrayList al = (ArrayList)result.get(key);
30 if (al == null) {
31 al = new ArrayList();
32 result.put(key, al);
33 }
34
35 al.add(objs[i]);
36 }
37
38 return result;
39 }
40 } else {
41 return null;
42 }
43 }
44
45 public static HashMap hashlizeObjects(List objs, IHashKey iHashKey) {
46 if (objs != null && !objs.isEmpty()) {
47 if (iHashKey == null) {
48 throw new RuntimeException("iHashKey cann't be null");
49 } else {
50 HashMap result = new HashMap();
51
52 for(int i = 0; i < objs.size(); ++i) {
53 String key = iHashKey.getKey(objs.get(i));
54 ArrayList al = (ArrayList)result.get(key);
55 if (al == null) {
56 al = new ArrayList();
57 result.put(key, al);
58 }
59
60 al.add(objs.get(i));
61 }
62
63 return result;
64 }
65 } else {
66 return null;
67 }
68 }
69
70 public static LinkedHashMap hashlizeObjectsLinked(List objs, IHashKey iHashKey) {
71 if (objs != null && !objs.isEmpty()) {
72 if (iHashKey == null) {
73 throw new RuntimeException("iHashKey cann't be null");
74 } else {
75 LinkedHashMap result = new LinkedHashMap();
76
77 for(int i = 0; i < objs.size(); ++i) {
78 String key = iHashKey.getKey(objs.get(i));
79 ArrayList al = (ArrayList)result.get(key);
80 if (al == null) {
81 al = new ArrayList();
82 result.put(key, al);
83 }
84
85 al.add(objs.get(i));
86 }
87
88 return result;
89 }
90 } else {
91 return null;
92 }
93 }
94
95 public static HashMap hashlizeMap(Object[] objs, IHashKey iHashKey) {
96 if (objs != null && objs.length != 0) {
97 if (iHashKey == null) {
98 throw new RuntimeException("iHashKey cann't be null");
99 } else {
100 HashMap result = new HashMap();
101
102 for(int i = 0; i < objs.length; ++i) {
103 String key = iHashKey.getKey(objs[i]);
104 result.put(key, objs[i]);
105 }
106
107 return result;
108 }
109 } else {
110 return null;
111 }
112 }
113
114 public static HashMap hashlizeMap(List objs, IHashKey iHashKey) {
115 if (objs != null && !objs.isEmpty()) {
116 if (iHashKey == null) {
117 throw new RuntimeException("iHashKey cann't be null");
118 } else {
119 HashMap result = new HashMap();
120
121 for(int i = 0; i < objs.size(); ++i) {
122 String key = iHashKey.getKey(objs.get(i));
123 result.put(key, objs.get(i));
124 }
125
126 return result;
127 }
128 } else {
129 return null;
130 }
131 }
132
133 public static HashMap hashlizeObjects(Object[] objs, IHashKey iHashKey, ICombine iCombine) {
134 if (objs != null && objs.length != 0) {
135 if (iHashKey == null) {
136 throw new RuntimeException("iHashKey cann't be null");
137 } else {
138 HashMap result = new HashMap();
139
140 for(int i = 0; i < objs.length; ++i) {
141 String key = iHashKey.getKey(objs[i]);
142 Object o = result.get(key);
143 result.put(key, iCombine.combine(o, objs[i]));
144 }
145
146 return result;
147 }
148 } else {
149 return null;
150 }
151 }
152
153 public static HashMap hashlizeObjects(List objs, IHashKey iHashKey, ICombine iCombine) {
154 if (objs != null && !objs.isEmpty()) {
155 if (iHashKey == null) {
156 throw new RuntimeException("iHashKey cann't be null");
157 } else {
158 HashMap result = new HashMap();
159 int size = objs.size();
160
161 for(int i = 0; i < size; ++i) {
162 String key = iHashKey.getKey(objs.get(i));
163 Object o = result.get(key);
164 result.put(key, iCombine.combine(o, objs.get(i)));
165 }
166
167 return result;
168 }
169 } else {
170 return null;
171 }
172 }
173
174 public static LinkedHashMap linkedHashlizeObjects(List objs, IHashKey iHashKey, ICombine iCombine) {
175 if (objs != null && !objs.isEmpty()) {
176 if (iHashKey == null) {
177 throw new RuntimeException("iHashKey cann't be null");
178 } else {
179 LinkedHashMap result = new LinkedHashMap();
180 int size = objs.size();
181
182 for(int i = 0; i < size; ++i) {
183 String key = iHashKey.getKey(objs.get(i));
184 Object o = result.get(key);
185 result.put(key, iCombine.combine(o, objs.get(i)));
186 }
187
188 return result;
189 }
190 } else {
191 return null;
192 }
193 }
194
195 public static Set<String> hashlizeSet(List objs, IHashKey iHashKey) {
196 if (CollectionUtils.isEmpty(objs)) {
197 return null;
198 } else if (iHashKey == null) {
199 throw new RuntimeException("iHashKey cann't be null");
200 } else {
201 Set<String> result = new HashSet();
202
203 for(int i = 0; i < objs.size(); ++i) {
204 String key = iHashKey.getKey(objs.get(i));
205 result.add(key);
206 }
207
208 return result;
209 }
210 }
211
212 public static List<String> hashlizeList(List objs, IHashKey iHashKey) {
213 if (CollectionUtils.isEmpty(objs)) {
214 return null;
215 } else if (iHashKey == null) {
216 throw new RuntimeException("iHashKey cann't be null");
217 } else {
218 List<String> result = new ArrayList();
219
220 for(int i = 0; i < objs.size(); ++i) {
221 String key = iHashKey.getKey(objs.get(i));
222 result.add(key);
223 }
224
225 return result;
226 }
227 }
228 }
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