Соблюдение контракта

Animal.java

package com.example.helloworld;

/**
 * Created by wannabe on 12.04.15.
 */
interface Animal
{
    int getLegsCount();
    animal move();
}

gistfile1.txt

Error:(13, 32) java: cannot find symbol
  symbol:   method getPosition()
  location: variable robert of type com.example.helloworld.animal

Main.java

package com.example.helloworld;

/**
 * Created by wannabe on 12.04.15.
 */
public class Main
{
    public static void main(String[] args)
    {
        animal robert = new Monkey();
        System.out.print(robert.getLegsCount());
        robert.move();
        System.out.print(robert.getPosition());
    }
}

Monkey.java

package com.example.helloworld;

/**
 * Created by wannabe on 12.04.15.
 */
public class Monkey implements Animal
{
    protected int position = 2;
    public int getLegsCount()
    {
        return 2;
    }
    public animal move()
    {
        this.position += 2;
        return this;
    }
    public int getPosition()
    {
        return this.position;
    }
}