遍历List集合按照某属性分类放到Map 

 1 import com.google.common.collect.Maps;
 2 import org.apache.commons.lang3.StringUtils;
 3  
 4 import java.lang.reflect.Method;
 5 import java.util.ArrayList;
 6 import java.util.List;
 7 import java.util.Map;
 8  
 9 public class ListChangeMapUtils {
10  
11     public static <T> Map<String, List<T>> objStringAndListToMapClassificationByName(List<T> list, String name) {
12         Map<String, List<T>> resultMap = Maps.newHashMap();
13         for (T obj : list) {
14             try {
15                 Method method = obj.getClass().getMethod("get" + name);
16                 String keyName = (String) method.invoke(obj);
17                 if (StringUtils.isBlank(keyName)) {
18                     continue;
19                 }
20                 List<T> tempList = null;
21                 if (!resultMap.containsKey(keyName)) {
22                     tempList = new ArrayList<>();
23                 } else {
24                     tempList = resultMap.get(keyName);
25                 }
26                 tempList.add(obj);
27                 resultMap.put(keyName, tempList);
28             } catch (Exception e) {
29  
30             }
31         }
32         return resultMap;
33     }
34  
35     public static <T> Map<Long, List<T>> objLongAndListToMapClassificationByName(List<T> list, String name) {
36         Map<Long, List<T>> resultMap = Maps.newHashMap();
37         for (T obj : list) {
38             try {
39                 Method method = obj.getClass().getMethod("get" + name);
40                 Long keyName = (Long) method.invoke(obj);
41                 if (keyName == null) {
42                     continue;
43                 }
44                 List<T> tempList = null;
45                 if (!resultMap.containsKey(keyName)) {
46                     tempList = new ArrayList<>();
47                 } else {
48                     tempList = resultMap.get(keyName);
49                 }
50                 tempList.add(obj);
51                 resultMap.put(keyName, tempList);
52             } catch (Exception e) {
53  
54             }
55         }
56         return resultMap;
57     }
58  
59     public static <T> Map<Integer, List<T>> objIntegerAndListToMapClassificationByName(List<T> list, String name) {
60         Map<Integer, List<T>> resultMap = Maps.newHashMap();
61         for (T obj : list) {
62             try {
63                 Method method = obj.getClass().getMethod("get" + name);
64                 Integer keyName = (Integer) method.invoke(obj);
65                 if (keyName == null) {
66                     continue;
67                 }
68                 List<T> tempList = null;
69                 if (!resultMap.containsKey(keyName)) {
70                     tempList = new ArrayList<>();
71                 } else {
72                     tempList = resultMap.get(keyName);
73                 }
74                 tempList.add(obj);
75                 resultMap.put(keyName, tempList);
76             } catch (Exception e) {
77  
78             }
79         }
80         return resultMap;
81     }
82 }

 

posted @ 2022-08-03 17:04  酷盖的小机灵  阅读(273)  评论(0)    收藏  举报