区别
Map map11122=new HashMap();
map11122.put("1", "A");
Map map11133=null;
map11133=map11122;
System.out.println("11111---"+map11133.toString());
Map map111221=new HashMap();
map111221.put("1", "A");
Map map111331=new HashMap();
map111331=map111221;
System.out.println("22222---"+map111331.toString());