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Simple Java Hashtable example

  1. /*
  2.   Simple Java Hashtable example
  3.   This simple Java Example shows how to use Java Hashtable. It also describes how to
  4.   add something to Hashtable and how to retrieve the value added from Hashtable.
  5. */
  6.  
  7. import java.util.Hashtable;
  8.  
  9. public class SimpleHashtableExample {
  10.  
  11.   public static void main(String[] args) {
  12.     //create object of Hashtable
  13.     Hashtable ht = new Hashtable();
  14.    
  15.     /*
  16.       Add key value pair to Hashtable using
  17.       Object put(Object key, Object value) method of Java Hashtable class,
  18.       where key and value both are objects
  19.       and can not be null.
  20.       put method returns Object which is either the value previously tied
  21.       to the key or null if no value mapped to the key.
  22.     */
  23.    
  24.     ht.put("One", new Integer(1));
  25.     ht.put("Two", new Integer(2));
  26.    
  27.     /*
  28.       Please note that put method accepts Objects. Java Primitive values CAN NOT
  29.       be added directly to Hashtable. It must be converted to corrosponding
  30.       wrapper class first.
  31.     */
  32.    
  33.     //retrieve value using Object get(Object key) method of Java Hashtable class
  34.     Object obj = ht.get("One");
  35.     System.out.println(obj);  
  36.    
  37.     /*
  38.        Please note that the return type of get method is Object. The value must
  39.        be casted to the original class.
  40.     */
  41.   }
  42. }
  43.  
  44. /*
  45. Output of the program would be
  46. 1
  47. */