Class UnboundedEnv

java.lang.Object
  |
  +--SquareEnvironment
        |
        +--UnboundedEnv

All Implemented Interfaces:

Environment

public class UnboundedEnv

extends SquareEnvironment

AP® Computer Science Marine Biology Simulation:
The UnboundedEnv class models an unbounded, two-dimensional, grid-like environment containing locatable objects. For example, it could be an environment of fish for a marine biology simulation.

Modification History: - Created to support multiple environment representations: this class represents a second implementation of the Environment interface.

The UnboundedEnv class is copyright© 2002 College Entrance Examination Board (www.collegeboard.com).

Version:

1 July 2002

See Also:

Locatable, Location

Constructor Summary

UnboundedEnv()
Constructs an empty UnboundedEnv object.

Method Summary

void	add(Locatable obj) Adds a new object to this environment at the location it specifies.
Locatable[]	allObjects() Returns all the objects in this environment.
protected int	indexOf(Location loc) Get the index of the object at the specified location.
boolean	isEmpty(Location loc) Determines whether a specific location in this environment is empty.
boolean	isValid(Location loc) Verifies whether a location is valid in this environment.
int	numCols() Returns number of columns in this environment.
int	numObjects() Returns the number of objects in this environment.
int	numRows() Returns number of rows in this environment.
Locatable	objectAt(Location loc) Returns the object at a specific location in this environment.
void	recordMove(Locatable obj, Location oldLoc) Updates this environment to reflect the fact that an object moved.
void	remove(Locatable obj) Removes the object from this environment.
java.lang.String	toString() Creates a single string representing all the objects in this environment (not necessarily in any particular order).

Methods inherited from class SquareEnvironment

getDirection, getNeighbor, neighborsOf, numAdjacentNeighbors, numCellSides, randomDirection

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

UnboundedEnv

public UnboundedEnv()

Constructs an empty UnboundedEnv object.

Method Detail

numRows

public int numRows()

Returns number of rows in this environment.

Returns:

the number of rows, or -1 if the environment is unbounded

numCols

public int numCols()

Returns number of columns in this environment.

Returns:

the number of columns, or -1 if the environment is unbounded

isValid

public boolean isValid(Location loc)

Verifies whether a location is valid in this environment.

Parameters:

loc - location to check

Returns:

true if loc is valid; false otherwise

numObjects

public int numObjects()

Returns the number of objects in this environment.

Returns:

the number of objects

allObjects

public Locatable[] allObjects()

Returns all the objects in this environment.

Returns:

an array of all the environment objects

isEmpty

public boolean isEmpty(Location loc)

Determines whether a specific location in this environment is empty.

Parameters:

loc - the location to test

Returns:

true if loc is a valid location in the context of this environment and is empty; false otherwise

objectAt

public Locatable objectAt(Location loc)

Returns the object at a specific location in this environment.

Parameters:

loc - the location in which to look

Returns:

the object at location loc; null if loc is empty

toString

public java.lang.String toString()

Creates a single string representing all the objects in this environment (not necessarily in any particular order).

Overrides:

toString in class java.lang.Object

Returns:

a string indicating all the objects in this environment

add

public void add(Locatable obj)

Adds a new object to this environment at the location it specifies. (Precondition: obj.location() is a valid empty location.)

Parameters:

obj - the new object to be added

Throws:

java.lang.IllegalArgumentException - if the precondition is not met

remove

public void remove(Locatable obj)

Removes the object from this environment. (Precondition: obj is in this environment.)

Parameters:

obj - the object to be removed

Throws:

java.lang.IllegalArgumentException - if the precondition is not met

recordMove

public void recordMove(Locatable obj,
                       Location oldLoc)

Updates this environment to reflect the fact that an object moved. (Precondition: obj.location() is a valid location and there is no other object there. Postcondition: obj is at the appropriate location (obj.location()), and either oldLoc is equal to obj.location() (there was no movement) or oldLoc is empty.)

Parameters:

obj - the object that moved

oldLoc - the previous location of obj

Throws:

java.lang.IllegalArgumentException - if the precondition is not met

indexOf

protected int indexOf(Location loc)

Get the index of the object at the specified location.

Parameters:

loc - the location in which to look

Returns:

the index of the object at location loc if there is one; -1 otherwise