All the classes intentionally are placed under the same package to hide the implementation from the user.

The user could use only the methods defined in the Graph interface plus the Edge, WeightedEdge and Vertex classes.

Gradle Lombok plugin was used to avoid writing boilerplate code.

1. Directed
2. Undirected
3. Directed Weighted
4. Undirected Weighted

1. Directed Unweighted UnweightedGraph<Integer> graph = UnweightedGraph.newDirected();

2. Undirected Unweighted UnweightedGraph<Integer> graph = UnweightedGraph.newUndirected();

3. Directed Weighted WeightedGraph<Integer> graph = WeightedGraph.newDirected();

4. Undirected Weighted WeightedGraph<Integer> graph = WeightedGraph.newUndirected();

A new vertex could be added as follows: graph.addVertex(1)

Depending on a graph type a new edge could be added either via graph.addEdge(1, 2) or graph.addEdge(1, 2, weight)

In order to find a path call graph.getPath(3,5) where 3 and 5 are vertices values. It will return a collection of edges which lie on the path.

• a) For Unweighted graphs the simple DFS traverse is used to perform searching, see SimplePathFindingStrategy

• b) For Weighted graphs a simplified implementation of Bellman–Ford algorithm is used, see BellmanFordPathFindingInWeightedGraphStrategy

  TODO: At the moment a simplified version of negative cycle detection is used

Graph.hasCycles() returns true if the given graph contains a cycle.

Graph.transform() allows transforming every Vertices' value according to the user-defined function

We assume that there are multiple readers and a very few writers so ReentrantReadWriteLock (see AbstractGraph class) is used to provide fast reading along with some level of consistency in the case when the graph or its vertices are being changed.

Edge - is an immutable class

Vertex - can be changed from the inside the package only. The value of Vertex could be immutable class so 'volatile' wouldn't be enough.

See the Graph interface for more methods and tests for more information on usage.