Pizza Fridge

Hi
I have to writ an new class for a project named "PizzaFride" in this
project are the 2 classes "Pizza" and PizzaFridg"
already given. Here are they:

/**
 * Class that represents a Pizza.
 *
 * @author David Schuler
 *
 */
public class Pizza {

    /**
     * Number of days the pizza is durable.
     */
    private int durableDays;

    /**

{
        return String.format("Pizza %s (noch %d Tage haltbar)", description,
                durableDays);
    }

    /**
     * Returns the number of days the pizza is durable.
     *
     * @return The number of days the pizza is durable
     */
    public int getDurableDays() {
        return durableDays;
    }

}

And the other class:

import java.util.ArrayList;
import java.util.List;

/**
 * Class that represents an intelligent pizza fridge, which keeps
track of the
 * durability of the contained pizzas.
 *
 * @author David Schuler
 *
 */
public class PizzaFridge {

    private List<Pizza> contents = new ArrayList<Pizza>();

    /**
     * Add a pizza to the fridge.
     */
    public void addPizza(Pizza item) {
        contents.add(item);
    }

    /**
     * Prints the contents of the fridge to the System.out.
     */
    public void printContent() {
        if (contents.size() == 0) {
            System.out.println("Der K=FChlschrank ist leer");
            return;
        }
        System.out.println("Der K=FChlschrank enth=E4lt:");
        for (Pizza item : contents) {
            System.out.println("\t" + item);
        }
    }

    /**
     * @return The pizza with the lowest number of durable days.
     */
    public Pizza whichPizzaShouldIEat() {
        if (contents.size() == 0) {
            return null;
        }
        Pizza pizzaToConsume = contents.get(0);
        int min = pizzaToConsume.getDurableDays();
        for (Pizza item : contents) {
            if (min > item.getDurableDays())
            {
                pizzaToConsume = item;
                min = pizzaToConsume.getDurableDays();
                System.out.println("Diese Pizza sollte als n=E4chstes
gegessen werden:");
                System.out.println(pizzaToConsume);
                preparePizza(pizzaToConsume); // i have paste this
line
           }

        }
        return pizzaToConsume;

    }

    /**
     * If the pizza is contained in the fridge it automatically
removed from the
     * fridge and then prepared. Otherwise an error message is given.
     *
     * @param pizza
     * The Pizza to prepare.
     */
    public void preparePizza(Pizza Pizza) {
        if (contents.contains(Pizza)) {
            contents.remove(Pizza);
            System.out.println("Diese Pizza wurde zubereitet:");
            System.out.println(Pizza);
        } else {
            System.out
                    .println("Diese Pizza ist nicht (mehr) im
K=FChlschrank enthalten");
        }
    }

}

My task was it to write a new class with the method usePizzaFridge().
This class should add 3 new pizzas and find out witch of this pizzas
should eat first. This pizza have to prepare.
My new class works only with th following text:

public class Joe
{

    private PizzaFridge PizzaFridge;
    private Pizza Pizza;

    public Joe()
    {

    }

    public void usePizzaFridge()
    {

        PizzaFridge = new PizzaFridge();
        Pizza = new Pizza (20, "Quattro Stagioni");
        PizzaFridge.addPizza(Pizza);
        Pizza = new Pizza (3, "Margherita");
        PizzaFridge.addPizza(Pizza);
        Pizza = new Pizza (17, "Pizza Napoli");
        PizzaFridge.addPizza(Pizza);
        PizzaFridge.printContent();
        PizzaFridge.whichPizzaShouldIEat();
        PizzaFridge.printContent();

    }

}

But if i change the durable days of the margherita pizza, for example
to 30 days the programm doesn't react and
prepare again the margherita pizza.
I hope someone can help me! thx!

(and sorry for my bad english)