title: Retrieving key from value in hashtable in Java
body: <p>I am a new bie to the world of collections but still, In my below class I have hashtable as I have to choose hashtable and I want to retrieve the key basis on the value , below is my class..</p>
  
  <pre><code>public class KeyFromValueExample
   {
  public static void main(String args[]) 
  {
  Hashtable table = new Hashtable();
          table.put("Sony", "Bravia");
          table.put("Samsung", "Galaxy");
          table.put("Nokia", "Lumia");
  System.out.println("does hash table has Lumia as value : " + table.containsValue("Lumia"));
          System.out.println("does hash table Lumia as key : " + table.containsKey("Lumia"));
  
          //finding key corresponding to value in hashtable - one to one mapping
          String key= null;
          String value="Lumia";
          for(Map.Entry entry: table.entrySet()){
              if(value.equals(entry.getValue())){
                  key = entry.getKey();
                  break; //breaking because its one to one map
              }
          }
          System.out.println("got key from value in hashtable key:  "+ key +" value: " + value);
  
  //finding key corresponding to value in hashtable - one to many mapping
          table.put("HTC", "Lumia");
          Set keys = new HashSet();
  
          for(Map.Entry entry: table.entrySet()){
              if(value.equals(entry.getValue())){
                  keys.add(entry.getKey()); //no break, looping entire hashtable
              }
          }
          System.out.println("keys : " + keys +" corresponding to value in hash table:  "+ value);
  </code></pre>
  
  <p>Output :-</p>
  
  <pre><code>does hash table has Lumia as value : true
  does hash table has Lumia as key : false
  got key from value in hashtable key:  Nokia value: Lumia
  keys : [Nokia, HTC] corresponding to value in hash talbe:  Lumia
  </code></pre>
  
  <p>Now please advis is there any other better way to achieve the same thing, Please advise if other better alternatives are there.</p>