TreeMap，HashMap，LinkedHashMap区别

TreeMap，HashMap，LinkedHashMap之间的区别和TreeSet，HashSet，LinkedHashSet之间的区别相似。

TreeMap：内部排序，内部使用了红黑树排序

HashMap：无序。

LinkedHashMap：顺序存取，内部是单向链表存储数据

 1 Map<String,String> map1=new LinkedHashMap<String,String>();
 2     Map<String,String> map2 = new TreeMap<>();
 3     Map<String,String> map3 = new HashMap<>();
 4     map1.put("d","111");
 5     map1.put("c","222");
 6     map1.put("a","333");
 7 
 8     map2.put("d","111");
 9     map2.put("c","222");
10     map2.put("a","333");
11 
12     map3.put("d","111");
13     map3.put("c","222");
14     map3.put("a","333");
15 
16 
17     System.out.print(map1.toString());
18     System.out.print("\n");
19     System.out.print(map2.toString());
20     System.out.print("\n");
21     System.out.print(map3.toString());
22        

输出：

{d=111, c=222, a=333}
{a=333, c=222, d=111}
{a=333, c=222, d=111}