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Get Collection of Values from Java Hashtable example

  1. /*
  2.   Get Collection of Values from Java Hashtable example
  3.   This Java Example shows how to get a Collection of values contained in Hashtable
  4.   using values method of Java Hashtable class.
  5. */
  6.  
  7. import java.util.Enumeration;
  8. import java.util.Iterator;
  9. import java.util.Hashtable;
  10. import java.util.Collection;
  11.  
  12. public class GetCollectionOfValuesFromHashtableExample {
  13.  
  14.   public static void main(String[] args) {
  15.    
  16.     //create Hashtable object
  17.     Hashtable ht = new Hashtable();
  18.    
  19.     //add key value pairs to Hashtable
  20.     ht.put("1","One");
  21.     ht.put("2","Two");
  22.     ht.put("3","Three");
  23.    
  24.     /*
  25.       get Collection of values contained in Hashtable using
  26.       Collection values() method of Hashtable class
  27.     */
  28.    
  29.     Collection c = ht.values();
  30.    
  31.     System.out.println("Values of Collection created from Hashtable are :");
  32.     //iterate through the collection
  33.     Iterator itr = c.iterator();
  34.     while(itr.hasNext())
  35.       System.out.println(itr.next());
  36.      
  37.     /*
  38.        Please note that resultant Collection object is backed by the Hashtable.
  39.        Any value that is removed from Collection will also be removed from
  40.        original Hashtable object. The same is not the case with the element
  41.        addition.
  42.     */
  43.    
  44.     //remove One from collection
  45.     c.remove("One");
  46.    
  47.     //print values of original values of Hashtable
  48.     System.out.println("Hashtable values after removal from Collection are :");
  49.     Enumeration e = ht.elements();
  50.     while(e.hasMoreElements())
  51.       System.out.println(e.nextElement());
  52.   }
  53. }
  54.  
  55. /*
  56. Output would be
  57. Values of Collection created from Hashtable are :
  58. Three
  59. Two
  60. One
  61. Hashtable values after removal from Collection are :
  62. Three
  63. Two
  64. */

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