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Snake.java
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Snake.java
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import java.util.ArrayList;
/**
* Represents the snake object in the game.
* Made up of SnakeTiles.
*
* @author Huy Nguyen
* @version (a version number or a date)
*/
public class Snake
{
private Grid grid;
private Location newLocation;
private ArrayList<SnakeTile> snake;
private Direction direction;
/**
* Creates a snake object with 3 tiles
* @param headTile The head tile of the snake
* @param middleTile The body tile of the snake
* @param tailTile The tail tile of the snake
*/
public Snake(Grid grid, SnakeTile headTile, SnakeTile middleTile, SnakeTile tailTile)
{
this.grid = grid;
newLocation = null;
snake = new ArrayList<SnakeTile>();
snake.add(tailTile);
snake.add(middleTile);
snake.add(headTile);
sane();
}
/**
* Ensures the snake is not empty, and exists on the grid
*/
public void sane()
{
assert snake.isEmpty() != true : "Snake is empty";
assert grid != null: "Grid is null";
}
/**
* Check the location from the given direction to the snake for movement.
* If the required location has a tile that is not edible, return false.
* @return Returns false if location cannot be moved to, true otherwise.
*/
public boolean canMove(Direction direction)
{
sane();
Location headLocation = snake.get(snake.size()-1).getLocation();
assert headLocation != null : "headLocation is null";
newLocation = null;
//Get the location to a given direction of the head of the snake
switch(direction)
{
case NORTH: if(headLocation.getRow() != 0) {
newLocation = grid.getNorthLocation(headLocation);
direction = Direction.NORTH;
}
else {
return false;
}
break;
case SOUTH: if(headLocation.getRow() != grid.getSize()-1) {
newLocation = grid.getSouthLocation(headLocation);
direction = Direction.SOUTH;
}
else {
return false;
}
break;
case EAST: if(headLocation.getCol() != grid.getSize()-1) {
newLocation = grid.getEastLocation(headLocation);
direction = Direction.EAST;
}
else {
return false;
}
break;
case WEST: if(headLocation.getCol() != 0) {
newLocation = grid.getWestLocation(headLocation);
direction = Direction.WEST;
}
else {
return false;
}
break;
}
//Determines whether the snake can move to specified tile
if(newLocation != null) {
Tile tile = grid.getTileAt(newLocation);
if(tile == null){
return true;
}
else if(tile instanceof FruitTile){
return true;
}
else {
return false;
}
}
else {
return false;
}
}
/**
* Move the snake to the next location
* @return If the snake eats a fruit during this step, return true. Otherwise false.
*/
public boolean move()
{
sane();
Tile tile = grid.getTileAt(newLocation);
//Blank space
if(tile == null) {
//Make new head tile of snake
SnakeTile newHeadTile = new SnakeTile(grid, newLocation);
snake.add(newHeadTile);
//Remove old tail tile of snake
SnakeTile tailTile = snake.get(0);
Location loc = tailTile.getLocation();
grid.clearTileAt(loc);
snake.remove(0);
return false;
}
//Finds a fruit
else if (tile instanceof FruitTile) {
//Clear the fruit from grid
grid.clearTileAt(tile.getLocation());
//Replace fruit with snake tile
SnakeTile newHeadTile = new SnakeTile(grid, newLocation);
snake.add(newHeadTile);
return true;
}
return false;
}
/**
* Returns the snake as an ArrayList of SnakeTiles
*/
public ArrayList<SnakeTile> getSnakeTiles()
{
sane();
return snake;
}
}