Avoid creating duplicated vertices in a digraph (using jgrapht)

Question

I am looking for a way to avoid creating duplicates in my digraph (I use the jgrapht library).

I read several topics that said: directedGraph.setCloneable(false); But this does not seem to be correct, cannot find it in the library documentation, and I get an error message on this line, saying that it does not exist.

I created my schedule using:

public static DirectedGraph<Point, DefaultEdge> directedGraph = new DefaultDirectedGraph<Point, DefaultEdge>(DefaultEdge.class);

And then he adds vertices to it based on the fill filling algorithm (adds vertices and edges when the algorithm passes through each point, below is part of it):

// Up
    xToFillNext = x-1;
    yToFillNext = y;
    if (xToFillNext==targetX && yToFillNext==targetY && !forbiddenDirection.equals(Direction.UP)) {
      Point myPoint = new Point(x, y);
      Point myNextPoint = new Point(xToFillNext, yToFillNext);

      directedGraph.addVertex(myPoint);
      directedGraph.addVertex(myNextPoint);
      directedGraph.addEdge(myPoint, myNextPoint);
      return true;
    } else if (xToFillNext>=0 && originValue==matrix[xToFillNext][yToFillNext] && !forbiddenDirection.equals(Direction.UP)) {  
      Point myPoint = new Point(x, y);
      Point myNextPoint = new Point(xToFillNext, yToFillNext);

      directedGraph.addVertex(myPoint);
      directedGraph.addVertex(myNextPoint);
      directedGraph.addEdge(myPoint, myNextPoint);   
      fillingReachedTargetPosition = 
        fillReachesTargetPosition(matrix, xToFillNext, yToFillNext, targetX, targetY, fillValue, Direction.DOWN );
      if (fillingReachedTargetPosition) {
        return true;
      }
    }

But when I print a list of vertices, there are duplicates from which I need to either get rid of or avoid creating them. Is there any way to do this?

EDIT: I created a Point class:

public static class Point {

  public int x;
  public int y;

  public  Point(int x, int y) 
  {

    this.x = x;
    this.y = y;
  }
  @Override
    public String toString() {
    return ("[x="+x+" y="+y+"]");
  }
}

Answer 1

, equals hashCode. Ohterwise JVM , (==), Point .

. (- )

@Override
public int hashCode() {
    int hash = 7;
    hash = 71 * hash + this.x;
    hash = 71 * hash + this.y;
    return hash;
}



@Override
public boolean equals(Object other) 
{
    if (this == other)
       return true;

    if (!(other instanceof Point))
       return false;

    Point otherPoint = (Point) other;
    return otherPoint.x == x && otherPoint.y == y;
}

Answer 2

:

import org.jgrapht.DirectedGraph;
import org.jgrapht.graph.DefaultDirectedGraph;
import org.jgrapht.graph.DefaultEdge;

import java.awt.Point;

public class JgraphtTest {
    public static void main(String[] args) {
        DirectedGraph<Point, DefaultEdge> directedGraph = new DefaultDirectedGraph<Point, DefaultEdge>(DefaultEdge.class);
        Point zero = new Point(0, 0), zero2 = new Point(0, 0), one = new Point(1, 1), two = new Point(2, 2);
        directedGraph.addVertex(zero);
        directedGraph.addVertex(one);
        directedGraph.addVertex(two);
        directedGraph.addVertex(zero2);   // should be a dup
        directedGraph.addEdge(zero, one);
        directedGraph.addEdge(one, two);
        directedGraph.addEdge(zero2, one); // should be a dup

        for (Point vertex : directedGraph.vertexSet()) {
            System.out.format("vertex: %s\n", vertex);
        }
        for (DefaultEdge edge : directedGraph.edgeSet()) {
            System.out.format("edge: %s\n", edge);
        }
    }
}

:

vertex: java.awt.Point[x=0,y=0]
vertex: java.awt.Point[x=1,y=1]
vertex: java.awt.Point[x=2,y=2]
edge: (java.awt.Point[x=0,y=0] : java.awt.Point[x=1,y=1])
edge: (java.awt.Point[x=1,y=1] : java.awt.Point[x=2,y=2])

, , Point, equals hashCode. , DirectedGraph , .