HashMap Example
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Here's the HashMap class, converted to using generics:

package examples;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

public class HashMapExample
{
  public static void main(String[] args)
  {
    HashMap<String, String> map = new HashMap<String, String>();
    map.put("Mary", "555-1234");
    map.put("Frank", "555-5678");
    map.put("Joe", "555-9012");
    map.put("Sylvia", "555-3456");
    map.put("Vanessa", "555-7890");
    map.put("Frank", "555-0987");   // Duplicate

    for (Iterator<Map.Entry<String, String>> iter = map.entrySet().iterator(); iter.hasNext(); )
    {
      Map.Entry<String, String> entry = iter.next(); // Note NO required cast
      String key = entry.getKey(); // Note NO required cast
      String value = entry.getValue(); // Note NO required cast
      System.out.println(key + ":" + value);
    }
  }
}

which outputs:

Vanessa:555-7890
Frank:555-0987
Sylvia:555-3456
Mary:555-1234
Joe:555-90

(This is not the same as the original -- it's in a different order -- but since it's a HashMap, the order isn't guaranteed, anyway.)

 

This page was last modified on 27 November, 2007