Question

I just tried to get add effect with ConcurrentHashMap<String,String> but the elements order is mixed.
Code like a…

ConcurrentHashMap<String,String>h=new ConcurrentHashMap<String,String>();

        for(int i=0; i<10; i++)
        {           
            h.put(""+Math.random(), ""+i);

        }

        Iterator<String> iterator=h.values().iterator();
        while(iterator.hasNext())
        {
            System.out.println(iterator.next());
        }

… gives in console next values:

9
4
6
2
0
5
1
7
3
8

… so my question is…

is there a way for ConcurrentHashMap to get original elements order if key is some random string?

Thanks

Answer 1

Use LinkedHashMap instead it will preserve the order of insertion

Hash table and linked list implementation of the Map interface, with predictable iteration order.

And use

Collections.synchronizedMap(mapInstance)

See Collections.synchronizedMap(mapINstance);

 Map<K,V> map = Collections.synchronizedMap(new LinkedHashMap());