java 中map去重合并

例如创建一个如下map对象Map >，外层的map对象的key重复一个或多次，现在需要将相同key的value全部整合在TreeMap里面去，保证外层的key唯一。需求是由于treeMap里面的key是一个时间戳，目标需要截取treemap里面的一个时间段的值。

(本人的GitHub链接https://github.com/Donjhon/spring-boot-demo.git，现在还在发展期，将自己工作学习的点滴共享出来)

   实现代码如下所示：

 

1. package com.pcitc.imp.example.util;
2. import java.util.HashMap;
3. import java.util.IdentityHashMap;
4. import java.util.Iterator;
5. import java.util.Map;
6. import java.util.Map.Entry;
7. import java.util.TreeMap;
8. public class MapTest {
9. public static void main(String[] args) {
10. Map<Object, TreeMap<String, Object>> tree = new IdentityHashMap<>();
11. TreeMap<String, Object> test0 = new TreeMap<>();
12. test0.put("11:01", 111);
13. test0.put("11:02", 222);
14. TreeMap<String, Object> test1 = new TreeMap<>();
15. test1.put("11:03", 333);
16. test1.put("11;04", 444);
17. String str1 = new String("1");
18. String str2 = new String("1");
19. String str3 = new String("2");
20. String str4 = new String("2");
21. tree.put(str1, test0);
22. tree.put(str2, test1);
23. tree.put(str3, test0);
24. tree.put(str4, test1);
25. System.out.println(tree);
26. Map<Object, TreeMap<String, Object>> map000 = mapK(tree);
27. System.out.println(map000);
28. }
29. @SuppressWarnings("rawtypes")
30. public static Map<Object, TreeMap<String, Object>> mapK(Map<Object, TreeMap<String, Object>> map) {
31. Map<Object, TreeMap<String, Object>> tree = new HashMap<>();
32. for (Entry<Object, TreeMap<String, Object>> vo : map.entrySet()) {
33. Object key1 = vo.getKey();
34. if (!tree.containsKey(key1)) {
35. tree.put(key1, vo.getValue());
36. } else {
37. TreeMap<String, Object> map1 = vo.getValue();
38. Iterator<?> iter = map1.entrySet().iterator();
39. while (iter.hasNext()) {
40. Map.Entry entry = (Map.Entry) iter.next();
41. String key = (String) entry.getKey();
42. Object integ = (Integer) entry.getValue();
43. tree.get(key1).put(key, integ);
44. }
45. }
46. }
47. return tree;
48. }
49. }