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

Map<String,String> map1=new LinkedHashMap<String,String>();
    Map<String,String> map2 = new TreeMap<>();
    Map<String,String> map3 = new HashMap<>();
    map1.put("d","111");
    map1.put("c","222");
    map1.put("a","333");

    map2.put("d","111");
    map2.put("c","222");
    map2.put("a","333");

    map3.put("d","111");
    map3.put("c","222");
    map3.put("a","333");


    System.out.print(map1.toString());
    System.out.print("\n");
    System.out.print(map2.toString());
    System.out.print("\n");
    System.out.print(map3.toString());
       

输出：

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