Write a Graph class in Java.  This class should represent undirected graphs. You can choose one of the representations from graph exercises, eg object model, sets of nodes and edges, adjacency matrix, or so on, whichever you feel most comfortable with. ● Include comments in your Java file to explain

1. Write a Graph class in Java. 
This class should represent undirected graphs. You can choose one of the representations
from graph exercises, eg object model, sets of nodes and edges, adjacency matrix, or so
on, whichever you feel most comfortable with.
● Include comments in your Java file to explain how nodes and edges are represented.
● Assume that only one edge can exist between two nodes.
● Assume that it is possible to have an edge connecting a node to itself, ie that a node
can be connected to itself via an edge.
● Because edges are undirected, an edge between v and w is also one between w and v.
● Your constructor method should take one parameter: the number of nodes of the
graph.

Add a method to your class: boolean addEdge that takes two parameters, v and
w (representing two modes v and w which are connected together by the edge
being added). 

If successful, the method should return true. The method should return false when it is
unsuccessful, which is in the following cases: the edge is already in the graph, or it is an edge
from or to a non existent node.