Greenfoot_Wombat

import greenfoot.*; // (World, Actor, GreenfootImage, and Greenfoot)

/** 
* Wombat. A Wombat moves forward until it hits the edge of the world, at 
* which point it turns left. If a wombat finds a leaf, it eats it. 
* 
* @author Michael Kölling 
* @version 2.0 
*/ 
public class Wombat extends Actor 
{ 
private int leavesEaten;

public Wombat()
{
    leavesEaten = 0;
}

/**
 * Do whatever the wombat likes to to just now.
 */
public void act()
{
    if (foundLeaf()) {
        eatLeaf();
    }
    else if (canMove()) {
        move();
    }
    else {
        turnLeft();
    }
}

/**
 * Move one step forward.
 */
public void move()
{
    move(1);
}

/**
 * Turn left by 90 degrees.
 */
public void turnLeft()
{
    turn(-90);
}

/**
 * Check whether there is a leaf in the same cell as we are.
 * Return true, if there is, false otherwise.
 */
public boolean foundLeaf()
{
    Actor leaf = getOneObjectAtOffset(0, 0, Leaf.class);
    return leaf != null;
}

/**
 * Eat a leaf (if there is one in our cell).
 */
public void eatLeaf()
{
    Actor leaf = getOneObjectAtOffset(0, 0, Leaf.class);
    if (leaf != null) {
        // eat the leaf...
        getWorld().removeObject(leaf);
        leavesEaten = leavesEaten + 1; 
    }
}

/**
 * Set the direction we're facing. The 'direction' parameter must
 * be in the range [0..3].
 */
public void setDirection(int direction)
{
    if ((direction >= 0) && (direction <= 3)) {
        setRotation(direction * 90);
    }
}

/**
 * Test if we can move forward. Return true if we can, false otherwise.
 */
public boolean canMove()
{
    int rotation = getRotation();
    int x = getX();
    int y = getY();
    boolean facingEdge = false;

    switch (rotation) {
        case 0:
            facingEdge = (x == getWorld().getWidth() - 1);
            break;
        case 90:
            facingEdge = (y == getWorld().getHeight() - 1);
            break;
        case 180:
            facingEdge = (x == 0);
            break;
        case 270:
            facingEdge = (y == 0);
            break;
    }

    return !facingEdge;
}

/**
 * Tell how many leaves we have eaten.
 */
public int getLeavesEaten()
{
    return leavesEaten;
}
}