Adjacency list representation of directed graph in ruby

Ruby program for Adjacency list representation of directed graph. Here problem description and explanation.

#    Ruby Program for 
#    Directed graph representation using adjacency list
class AjlistNode 
	# Define the accessor and reader of class AjlistNode
	attr_reader :id, :next
	attr_accessor :id, :next
	#  Vertices node key
	def initialize(id) 
		#  Set value of node key
		self.id = id
		self.next = nil
	end

end

class Vertices 
	# Define the accessor and reader of class Vertices
	attr_reader :data, :next, :last
	attr_accessor :data, :next, :last
	def initialize(data) 
		self.data = data
		self.next = nil
		self.last = nil
	end

end

class Graph 
	# Define the accessor and reader of class Graph
	attr_reader :size, :node
	attr_accessor :size, :node
	#  Number of Vertices
	def initialize(size) 
		#  Set value
		self.size = size
		self.node = Array.new(size) {nil}
		self.setData()
	end

	#  Set initial node value
	def setData() 
		if (self.size <= 0) 
			print("\nEmpty Graph\n")
		else
 
			index = 0
			while (index < self.size) 
				#  Set initial node value
				self.node[index] = Vertices.new(index)
				index += 1
			end

		end

	end

	#  Connect two nodes
	def connect(start, last) 
		edge = AjlistNode.new(last)
		if (self.node[start].next == nil) 
			self.node[start].next = edge
		else
 
			#  Add edge at the end
			self.node[start].last.next = edge
		end

		#  Get last edge 
		self.node[start].last = edge
	end

	#   Handling the request of adding new edge
	def addEdge(start, last) 
		if (start >= 0 && start < self.size && 
            last >= 0 && last < self.size) 
			#  Safe connection
			self.connect(start, last)
		else
 
			#  When invalid nodes
			print("\nHere Something Wrong\n")
		end

	end

	def printGraph() 
		if (self.size > 0) 
			index = 0
			#  Print graph ajlist Node value
			while (index < self.size) 
				print("\nAdjacency list of vertex ", index ," :")
				temp = self.node[index].next
				while (temp != nil) 
					#  Display graph node 
					print("  ", self.node[temp.id].data)
					#  visit to next edge
					temp = temp.next
				end

				index += 1
			end

		end

	end

end

def main() 
	#  5 implies the number of nodes in graph
	g = Graph.new(5)
	#  Connect node with an edge
	g.addEdge(0, 1)
	g.addEdge(1, 2)
	g.addEdge(1, 4)
	g.addEdge(2, 0)
	g.addEdge(2, 3)
	g.addEdge(4, 3)
	#  print graph element
	g.printGraph()
end

main()

Output

Adjacency list of vertex 0 :  1
Adjacency list of vertex 1 :  2  4
Adjacency list of vertex 2 :  0  3
Adjacency list of vertex 3 :
Adjacency list of vertex 4 :  3