package net.datastructures;
/**
 * An interface for a map which binds a key uniquely to a value.
 * @author Michael Goodrich
 */
//begin#fragment Map
// A simple Map interface
public interface Map<K,V> {
  /** Returns the number of items in the map. */ 
  public int size();
  /** Returns whether the map is empty. */
  public boolean isEmpty();
  /** 
    * If there is an entry with the specified key, replaces the value of
    * this entry with the specified value and returns the old value. Else,
    * adds a new entry with the specified key and value and returns null.
    */
  public V put(K key, V value) throws InvalidKeyException;
  /** 
   * Returns the value of the entry containing the given key.  Returns
   * null if no such entry exists.
   */
  public V get(K key) throws InvalidKeyException;
  /** 
   * If there is an entry with the specified key, removes this entry and
   * returns its value. Else, returns null.
   */
  public V remove(K key) throws InvalidKeyException;
  /** Returns an iterable object containing all the keys in the map. */
  public Iterable<K> keySet();
  /** Returns an iterable object containing all the values in the map. */
  public Iterable<V> values();
  /** Returns an iterable object containing all the entries in the map. */
  public Iterable<Entry<K,V>> entrySet();  
}
//end#fragment Map