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

/**
 * This class represents a coin.  Only a single Coin
 * with a particular value can be created. This class 
 * implements the multiton design pattern.
 * 
 * @author Franck van Breugel
 */
public class Coin
{
    private int value;
    
    /**
     * The unique instances.
     */
    private static Map<Integer, Coin> instance = new HashMap<Integer, Coin>();
    
    /**
     * Initializes the coin.
     */
    private Coin(int value) 
    {
	this.setValue(value);
    } 

    /**
     * Returns the value of this coin.
     * 
     * @return the value of this coin.
     */
    public int getValue()
    {
	return this.value;
    }

    /**
     * Sets the value of this coin to the given value.
     * 
     * @param value the new value of this coin.
     */
    private void setValue(int value)
    {
	this.value = value;
    }

    /**
     * Returns the coin with the given value.
     * 
     * @return the coin with the given value.
     */
    public static Coin getInstance(int value)
    {
	if (!Coin.instance.containsKey(value))
	{
	    Coin.instance.put(value, new Coin(value));
	}
	return Coin.instance.get(value);
    }
}