java - Dijkstra's shortest path algorithm Lars Vogel -

i'm trying implement dijkstra algorithm in java site of lars vogel :
http://www.vogella.com/articles/javaalgorithmsdijkstra/article.html.
there no main function , when create 1 public static void gives me errors non-static variables or classes cannot referenced static context.
have make classes static or there solution?

    package de.vogella.algorithms.dijkstra.test;  import java.util.arraylist; import java.util.linkedlist; import java.util.list;  import org.junit.test;  import de.vogella.algorithms.dijkstra.engine.dijkstraalgorithm; import de.vogella.algorithms.dijkstra.model.edge; import de.vogella.algorithms.dijkstra.model.graph; import de.vogella.algorithms.dijkstra.model.vertex;  import static org.junit.assert.assertnotnull; import static org.junit.assert.asserttrue;   public class testdijkstraalgorithm {     private list<vertex> nodes;   private list<edge> edges;    @test   public void testexcute() {     nodes = new arraylist<>();     edges = new arraylist<>();     (int = 0; < 11; i++) {       vertex location = new vertex("node_" + i, "node_" + i);       nodes.add(location);     }      addlane("edge_0", 0, 1, 85);     addlane("edge_1", 0, 2, 217);     addlane("edge_2", 0, 4, 173);     addlane("edge_3", 2, 6, 186);     addlane("edge_4", 2, 7, 103);     addlane("edge_5", 3, 7, 183);     addlane("edge_6", 5, 8, 250);     addlane("edge_7", 8, 9, 84);     addlane("edge_8", 7, 9, 167);     addlane("edge_9", 4, 9, 502);     addlane("edge_10", 9, 10, 40);     addlane("edge_11", 1, 10, 600);      // lets check location loc_1 loc_10     graph graph = new graph(nodes, edges);     dijkstraalgorithm dijkstra = new dijkstraalgorithm(graph);     dijkstra.execute(nodes.get(0));     linkedlist<vertex> path = dijkstra.getpath(nodes.get(10));      assertnotnull(path);     asserttrue(path.size() > 0);      (vertex vertex : path) {       system.out.println(vertex);     }    }    private void addlane(string laneid, int sourcelocno, int destlocno,       int duration) {     edge lane = new edge(laneid,nodes.get(sourcelocno), nodes.get(destlocno), duration);     edges.add(lane);   }    public  static void main() {       testexcute();   } } 

run directly code:

public static void main() {     new testdijkstraalgorithm().testexcute(); } 

you have create instance of class first. mainmethod static, can't call instance methods (non-static) directly. create instance, call constructor new testdijkstraalgorithm(). there no constructor defined explicitly, default one, without parameters, automatically available.

these oop basics, should read it.

that being said, supposed way call testexecutemethod junit. that's why there @test annotation.