Grid World

Question 1

Location class constructor:

Answer 1

public Location(int row, int col)

Question 2

Location accessor methods:

Answer 2

public int getRow();

public int getCol();

Question 3

Location objects are _______

Answer 3

immutable. Once created, a Location object CANNOT change.

Question 4

Location implements ________ and provides a _________ method that compares locations first by ____ and then, if equal, by _____.

Answer 4

Comparable, compareTo, row, column. Location also overrides Object’s equals method in a manner consistent with compareTo.

Question 5

Location’s toString method converts a ____ into a ____

Answer 5

location, string

Question 6

The Location class defines eight public constants:

Answer 6

public static final int NORTH = 0;
public static final int NORTHEAST = 45;
public static final int EAST = 90;
public static final int SOUTHEAST = 135;
public static final int SOUTH = 180;
public static final int SOUTHWEST = 225;
public static final int WEST = 270;
public static final int NORTHWEST = 315;

Question 7

Seven more constants represent turns, with right turns being ______ and left turns _____

Answer 7

positive, negative.

public static final int AHEAD = 0;

Question 8

Location’s getAdjacentLocation(int dir) method:

Answer 8

returns the location that is adjacent to this location in the compass direction dir. Locations that touch in a corner are considered adjacent.

Question 9

Location’s getDirectionToward(Location other) method:

Answer 9

returns the compass direction (in degrees) from this location to other.

Question 10

Grid int numRows() method:

Answer 10

returns the number of rows for a bounded grid; -1 for an unbounded grid

Question 11

Grid int numCols() method:

Answer 11

returns the number of columns for a bounded grid; -1 for an unbounded grid

Question 12

Grid boolean isValid(Location loc) method:

Answer 12

returns true if loc is valid in this grid (always true for an unbounded grid). DOES NOT tell whether or not the space is occupied

Question 13

Grid E get(Location loc) method:

Answer 13

returns the object at loc (or null if loc is empty)

Question 14

Grid E put(Location loc, E obj) method:

Answer 14

puts obj at loc and returns the object previously at loc (or null if loc was empty)

Question 15

Grid E remove(Location loc) method:

Answer 15

Removes the object at loc and returns that object (or null if loc was empty)

Question 16

Grid ArrayList getOccupiedLocations() method:

Answer 16

returns the list of all occupied locations in the grid

Question 17

Grid ArrayList getValidAdjacentLocations(Location loc) method:

Answer 17

Returns a list of all valid locations adjacent to loc

Question 18

Grid ArrayList getEmptyAdjacentLocations(Location loc) method:

Answer 18

returns a list of all valid empty locations adjacent to loc

Question 19

Grid ArrayList getOccupiedAdjacentLocations(Location loc) method:

Answer 19

returns a list of all valid occupied locations adjacent to loc

Question 20

Grid ArrayList getNeighbors(Location loc) method:

Answer 20

returns a list of all objects in the occupied locations adjacent to loc