Class Lane

java.lang.Object

Lane

public class Lane
extends java.lang.Object

Represents a lane as an array of Vehicles. A position in the lane may be occupied by a vehicle or free (contains null). Vehicles enter the lane at the high index of the array end exit from index 0.

Constructor Summary

Constructors

Constructor and Description
Lane(int length) Constructs a lane with a specified capacity.

Method Summary

Modifier and Type	Method and Description
Vehicle	getFirst() Access method for the vehicle in the first position.
boolean	lastFree() Checks if the last position is free.
static void	main(java.lang.String[] args) Demonstrates the use of the the class and it's methods.
int	numberOfVehicles() Counts the number of Vehicles on the lane.
void	putLast(Vehicle v) Put a vehicle in the last position.
Vehicle	removeFirst() Removes the first vehicle (index 0) from the lane and makes it empty.
void	step() Advances all except the first vehicle one position provided the target position is free.
java.lang.String	toString() A string representation of the lane.

Methods inherited from class java.lang.Object

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

Constructor Detail

Lane

public Lane(int length)

Constructs a lane with a specified capacity.

Parameters:

length - The length (capacity) of the lane in number of vehicles

Method Detail

toString

public java.lang.String toString()

A string representation of the lane.

Overrides:

toString in class java.lang.Object

Returns:

The string representation

step

public void step()

Advances all except the first vehicle one position provided the target position is free. The process starts in the low end (i. e. at index 1).

Example: The follwing two lines shows the result of a call to toString before and after a call to step()

    <XX  X   X X X  XX>
    <XX X   X X X  XX >
 

removeFirst

public Vehicle removeFirst()

Removes the first vehicle (index 0) from the lane and makes it empty.

Returns:

The removed vehicle or null if the position was empty

getFirst

public Vehicle getFirst()

Access method for the vehicle in the first position.

Returns:

A reference to the vehicle in the first position

lastFree

public boolean lastFree()

Checks if the last position is free.

Returns:

true if the last position is free (null) else false.

putLast

public void putLast(Vehicle v)

Put a vehicle in the last position.

Parameters:

v - Vehicle to be put in the last position

Throws:

java.lang.RuntimeException - if the last position is not free

numberOfVehicles

public int numberOfVehicles()

Counts the number of Vehicles on the lane.

Returns:

The number of Vehicles

main

public static void main(java.lang.String[] args)

Demonstrates the use of the the class and it's methods.