import java.util.*;

class ETable1 implements ETable
{
// Table class with Enumeration, 
// data stored in unordered partly-filled arrays

 private KeyObject[] array;
 private int count;
 final static int MAX=100;

 public ETable1()
 {
  array = new KeyObject[MAX];
 }

 public boolean delete(String key)
 {
  int i;
  for(i=0; i<count&&!array[i].equalKey(key); i++) {}
  if(i<count)
     {
      array[i]=array[count-1];
      count--;
      return true;
     }
  else
     return false;
 }

 public void add(KeyObject obj)
 {
  int i;
  for(i=0; i<count&&!array[i].equalKey(obj); i++) {}
  if(i==count)
     array[count++] = obj;
 }

 public KeyObject retrieve(String key)
 {
  int i;
  for(i=0; i<count&&!array[i].equalKey(key); i++) {}
  if(i==count)
     return null;
  else
     return array[i];
 }

 public Enumeration getEnumeration()
 {
  return new MyEnumeration();
 }

 private class MyEnumeration implements Enumeration
 {
  int current;

  MyEnumeration()
  {
   current=0;
  }

  public boolean hasMoreElements()
  {
   return current<count;
  }

  public Object nextElement()
  {
   return array[current++];
  }
 }
}