LinkedHashMap是Map接口的实现类，key以LinkedHashSet存储。

哈希表散列Key，链表维持Key的添加顺序。

 

LinkedHashMap的添加和遍历：

1 public class Demo1 { 2  3     public static void main(String[] args) { 4         /*HashMap
     
       map=new HashMap
      
       (); 5         Student student=new Student(1,"大明",20); 6         Student student1=new Student(1,"大明",20); 7         Student student2=new Student(3,"舔狗",22); 8          9         ArrayList
       
         list=new ArrayList
        
         ();10         list.add("3333");11         list.add("444");12         map.put(student1, list);13         map.put(student2, list); 14         map.put(student, list);15         16         System.out.println(map);*/17         18         LinkedHashMap
         
           linkedHashMap=new LinkedHashMap
          
           ();19 ArrayList
           
             arrayList=new ArrayList
            
             ();20 arrayList.add("333");21 arrayList.add("999");22 arrayList.add("555");23 24 ArrayList
             
               arrayList1=new ArrayList
              
               ();25 arrayList1.add("AAA");26 arrayList1.add("EEE");27 arrayList1.add("QQQ");28 29 linkedHashMap.put("1",arrayList);30 linkedHashMap.put("1",arrayList1);31 32 Set
               
                 keys=linkedHashMap.keySet();33 /*for (String string : keys) {34 System.out.println(string+"="+linkedHashMap.get(string));35 }*/36 java.util.Iterator
                
                  iterator=keys.iterator();37 while(iterator.hasNext()){38 String key=iterator.next();39 System.out.println(key+"="+linkedHashMap.get(key));40 }41 42 43 }44 45 }