Package lejos.robotics.pathfinding

Class RandomSelfGeneratingNode

java.lang.Object

lejos.robotics.pathfinding.Node

lejos.robotics.pathfinding.RandomSelfGeneratingNode

public class RandomSelfGeneratingNode
extends Node

This Node is able to randomly generate its own neighbors via the getNeighbors() method. The number of neighbors and possible distances to the neighbors are determined in the constructor. The first instance of this node is generally the start node used in algorithms. The goal node is just a regular node that is automatically linked to this set when the dynamically created nodes come within range of the goal node. Note: Because the nodes are randomly generated, there is no guarantee they will come within range of the goal node and successfully link up. However, in practice they will always connect if you use enough connections (minimum 3-4) and a long enough maxDist.

Field Summary

Fields

Modifier and Type	Field and Description
private int	connections
private boolean	firstCall firstCall indicates if getNeighbors() has been called yet.
private static Node	goal
private float	maxDist

Fields inherited from class lejos.robotics.pathfinding.Node

MULTIPLIER, x, y

Constructor Summary

Constructors

Constructor and Description
RandomSelfGeneratingNode(float x, float y, float maxDist, int connections) Creates a node that will randomly generate 'connections' number of neighbors when getNeighbors() is called.
RandomSelfGeneratingNode(float x, float y, float maxDist, int connections, Node goal) Creates a node that will randomly generate 'connections' number of neighbors when getNeighbors() is called.

Method Summary

Modifier and Type	Method and Description
java.util.Collection<Node>	getNeighbors() When this method is called the first time, it randomly generates a set of neighbors according to the parameters in the constructor.

Methods inherited from class lejos.robotics.pathfinding.Node

addNeighbor, calculateG, calculateH, getF_Score, getG_Score, getPredecessor, neighbors, removeNeighbor, setG_Score, setH_Score, setPredecessor

Methods inherited from class java.lang.Object

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

Field Detail

firstCall

private boolean firstCall

firstCall indicates if getNeighbors() has been called yet. false = has been called

connections

private int connections

maxDist

private float maxDist

goal

private static Node goal

Constructor Detail

RandomSelfGeneratingNode

public RandomSelfGeneratingNode(float x,
                                float y,
                                float maxDist,
                                int connections)

Creates a node that will randomly generate 'connections' number of neighbors when getNeighbors() is called. These neighbors will be within range of 'maxDist'.

Parameters:

x - The x coordinate of this node.

y - The y coordinate of this node.

maxDist - The maximum x or y distance to create new nodes randomly.

connections - The number of neighbors to randomly generate and connect with.

RandomSelfGeneratingNode

public RandomSelfGeneratingNode(float x,
                                float y,
                                float maxDist,
                                int connections,
                                Node goal)

Creates a node that will randomly generate 'connections' number of neighbors when getNeighbors() is called. These neighbors will be within range of 'maxDist'.

Parameters:

x - The x coordinate of this node.

y - The y coordinate of this node.

maxDist - The maximum x or y distance to create new nodes randomly.

connections - The number of neighbors to randomly generate and connect with.

goal - The goal node which is added to this set and connected to any nodes within range.

Method Detail

getNeighbors

public java.util.Collection<Node> getNeighbors()

When this method is called the first time, it randomly generates a set of neighbors according to the parameters in the constructor. It then calls addNeighbor() for each one. The next time getNeighbors() is called it will return the same set of neighbors it initially generated. Each of these neighbors is a RandomSelfGeneratingNode too, so when their neighbors are requested they will also self-generate a set of neighbors. Each random node will also add the "parent" node to its list of neighboring nodes. If a goal node was added, it checks if the node is within maxDist of the goal node. If it is, both the goal node and this node add each other as neighbors.

Overrides:

getNeighbors in class Node

Returns:

a collection of RandomSelfGeneratingNode objects.