Traversal of the Java map object

In general, the most common implementation class for a map is HashMap.

The traversal of a map is also an iterative

1. Use entries to traverse in the For-each loop (both key and value are taken)

New Hashmap<string, string>();      for (map.entry<string, string>map.entryset ()) {        System.out.println(entry.getkey () + ", Value:" +  entry.getvalue ());    }

2. Traverse keys or values (value or Fetch key) in the For-each loop

New Hashmap<string, string>();     // Fetch key    for  Map.keyset ()) {        System.out.println ("key:" + key);   }    //Fetch value    for  map.values ()) {        System.out.println ("value:" + value);  }  

3. Using iterator traversal

New Hashmap<string, string>();    Iterator<map.entry<string, string>> entries =  map.entryset (). Iterator ();      while (Entries.hasnext ()) {        map.entry<string, string> Entry = entries.next ();      System.out.println ("Key:" + entry.getkey () + ", Value:" + Entry.getvalue ());    }

4. Key to find the value traversal get (key), it is generally known that a key directly get the value, no longer loop traversal.

Traversal of the Java map object