Eclipse无法解析类型，但是类在构建路径上

Question

I have done about 4 hours worth of internet hunting and have hit my limit. Hopefully you folks can help.

I have a project that has a package that contains some source code. I also have my main source folder which contains this package as well.

In the package directory I have source files, not class files, defined. I used this directory as a source folder, and that works. One of my source files in my main source folder instantiates an object defined in this source file. I need to pass this object a reference to the calling object to be able to callback. So, for example:

package edu.uci.ics.jung.visualization3d;

import java.awt.BorderLayout;
import java.awt.Font;
import java.awt.GraphicsConfiguration;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import java.util.HashMap;
import java.util.Map;

import javax.media.j3d.AmbientLight;
import javax.media.j3d.Appearance;
import javax.media.j3d.BoundingSphere;
import javax.media.j3d.Bounds;
import javax.media.j3d.BranchGroup;
import javax.media.j3d.Canvas3D;
import javax.media.j3d.DirectionalLight;
import javax.media.j3d.Font3D;
import javax.media.j3d.FontExtrusion;
import javax.media.j3d.Group;
import javax.media.j3d.Material;
import javax.media.j3d.Node;
import javax.media.j3d.OrientedShape3D;
import javax.media.j3d.Text3D;
import javax.media.j3d.Transform3D;
import javax.media.j3d.TransformGroup;
import javax.swing.JPanel;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import javax.vecmath.Color3f;
import javax.vecmath.Point3d;
import javax.vecmath.Point3f;
import javax.vecmath.Vector3f;

import org.apache.commons.collections15.BidiMap;
import org.apache.commons.collections15.bidimap.DualHashBidiMap;

import com.sun.j3d.utils.behaviors.mouse.MouseWheelZoom;
import com.sun.j3d.utils.geometry.Primitive;
import com.sun.j3d.utils.picking.PickTool;
import com.sun.j3d.utils.picking.behaviors.PickingCallback;
import com.sun.j3d.utils.universe.SimpleUniverse;

import edu.uci.ics.jung.algorithms.layout.util.VisRunner;
import edu.uci.ics.jung.algorithms.layout3d.Layout;
import edu.uci.ics.jung.algorithms.util.IterativeContext;
import edu.uci.ics.jung.graph.Graph;
import edu.uci.ics.jung.graph.util.Context;
import edu.uci.ics.jung.graph.util.Pair;
import edu.uci.ics.jung.visualization.picking.MultiPickedState;
import edu.uci.ics.jung.visualization.picking.PickedState;
import edu.uci.ics.jung.visualization3d.control.MouseRotate;
import edu.uci.ics.jung.visualization3d.control.MouseTranslate;
import edu.uci.ics.jung.visualization3d.control.PickSphereBehavior;
import edu.uci.ics.jung.visualization3d.control.PickTranslateBehavior;
import edu.uci.ics.jung.visualization3d.layout.LayoutEventBroadcaster;



public class VisualizationViewer<V,E> extends JPanel {

    BranchGroup objRoot;
    TransformGroup objTrans;
    GraphBuilder to;
//  Appearance vertexLook;
//  Appearance edgeLook;
    Appearance grayLook;
    /**
     * a listener used to cause pick events to result in
     * repaints, even if they come from another view
     */
    protected ItemListener pickEventListener;
    /**
     * holds the state of which vertices of the graph are
     * currently 'picked'
     */
    protected PickedState<V> pickedVertexState;

    /**
     * holds the state of which edges of the graph are
     * currently 'picked'
     */
    protected PickedState<E> pickedEdgeState;

    protected RenderContext<V,E> renderContext = new PluggableRenderContext<V,E>();

    BidiMap<V,VertexGroup> vertexMap = new DualHashBidiMap<V,VertexGroup>();
    Map<E,EdgeGroup> edgeMap = new HashMap<E,EdgeGroup>();
    Graph<V,E> graph;
    Layout<V,E> layout;

    public VisualizationViewer() {
//      controls = createControls();
        setLayout(new BorderLayout());

        renderContext.setPickedVertexState(new MultiPickedState<V>());
        renderContext.setPickedEdgeState(new MultiPickedState<E>());
        GraphicsConfiguration config = 
            SimpleUniverse.getPreferredConfiguration();
        final Canvas3D c = new Canvas3D(config);
        add(c, BorderLayout.CENTER);
        setPickedVertexState(new MultiPickedState<V>());
        setPickedEdgeState(new MultiPickedState<E>());

        // Create a SpringGraph scene and attach it to the virtual universe
        BranchGroup scene = createSceneGraph(c);
        SimpleUniverse u = new SimpleUniverse(c);
        u.getViewer().getView().setUserHeadToVworldEnable(true);    

        // This will move the ViewPlatform back a bit so the
        // objects in the scene can be viewed.
        u.getViewingPlatform().setNominalViewingTransform();

        c.getView().setBackClipDistance(20.0);
        //c.getView().setFrontClipDistance(10.0);
        u.addBranchGraph(scene);
    }

    public Layout<V,E> getGraphLayout() {
        return layout;
    }


    public BranchGroup createSceneGraph(final Canvas3D canvas) {

        objRoot = new BranchGroup();
        objRoot.setCapability(Group.ALLOW_CHILDREN_EXTEND);
        objRoot.setCapability(Group.ALLOW_CHILDREN_WRITE);

        TransformGroup objScale = new TransformGroup();
        Transform3D t3d = new Transform3D();
//      t3d.setScale(0.05);
        objScale.setTransform(t3d);
        objRoot.addChild(objScale);

        Transform3D tt = new Transform3D();
        tt.setScale(.05);
        tt.setTranslation(new Vector3f(0, 0, -30.f));
        objTrans = new TransformGroup(tt);
        objTrans.setCapability(TransformGroup.ALLOW_TRANSFORM_WRITE);
        objTrans.setCapability(TransformGroup.ALLOW_TRANSFORM_READ );
        objTrans.setCapability(TransformGroup.ALLOW_CHILDREN_EXTEND);
        objScale.addChild(objTrans);
//      objRoot.addChild(objTrans);

        // Create Colors, Materials,  and Appearances.
        Appearance look = new Appearance();
        Color3f objColor = new Color3f(0.7f, 0.7f, 0.7f);
        Color3f black = new Color3f(0.f, 0.f, 0.f);
        Color3f white = new Color3f(1.0f, 1.0f, 0.6f);
        Color3f gray  = new Color3f(.2f, .2f, .2f);
        Color3f red = new Color3f(1.0f, 0, 0);
        Color3f yellow = new Color3f(1,1,0);

        Material objMaterial = new Material(objColor, black,
                objColor, white, 100.0f);
        Material blackMaterial = new Material(objColor, black,
                black, objColor, 10.0f);
        Material whiteMaterial = new Material(white, white,
                white, white, 100.0f);
        Material grayMaterial = new Material(gray, black,
                gray, gray, 100.0f);

        Material redMaterial = new Material(red, black,
                red, red, 100.0f);
            Material yellowMaterial = new Material(yellow, black, 
                yellow, yellow, 100);

        look.setMaterial(new Material(objColor, black,
                objColor, white, 100.0f));
        Appearance blackLook = new Appearance();
        blackLook.setMaterial(blackMaterial);

        Appearance whiteLook = new Appearance();
        whiteLook.setMaterial(whiteMaterial);

        Appearance grayLook = new Appearance();
        grayLook.setMaterial(grayMaterial);
        grayLook.setCapability(Appearance.ALLOW_MATERIAL_READ);
        grayLook.setCapability(Appearance.ALLOW_MATERIAL_WRITE);

        final Appearance redLook = new Appearance();
        redLook.setMaterial(redMaterial);
//      vertexLook = redLook;

        Appearance objLook = new Appearance();
        objLook.setMaterial(objMaterial);
        grayLook = objLook;
        final Appearance yellowLook = new Appearance();
        yellowLook.setMaterial(yellowMaterial);
        Bounds bounds =
            new BoundingSphere(new Point3d(),
                    300);

        MouseRotate behavior1 = new MouseRotate();
        behavior1.setTransformGroup(objTrans);
        objTrans.addChild(behavior1);
        behavior1.setSchedulingBounds(bounds);

        MouseWheelZoom behavior2 = new MouseWheelZoom();
        behavior2.setTransformGroup(objTrans);
//      behavior2.setFactor(10);
        objTrans.addChild(behavior2);
        behavior2.setSchedulingBounds(bounds);

        MouseTranslate behavior3 = new MouseTranslate();
        behavior3.setTransformGroup(objTrans);
        objTrans.addChild(behavior3);
        behavior3.setSchedulingBounds(bounds);

        PickTranslateBehavior ptb = new PickTranslateBehavior(objRoot,canvas,bounds,PickTool.GEOMETRY);
        ptb.setSchedulingBounds(bounds);
//      objTrans.addChild(ptb);
        ptb.setupCallback(new PickingCallback() {

            public void transformChanged(int type, TransformGroup tg) {
                if(tg == null) return;
                Transform3D t3d = new Transform3D();
                tg.getTransform(t3d);
//              System.err.println(tg+" transformChanged \n"+t3d);
                Point3f p1 = new Point3f();
                V v = vertexMap.getKey(tg);
//              Transform3D lvw = new Transform3D();
//              tg.getLocalToVworld(lvw);
//              System.err.println("lvw = \n"+lvw);
//              lvw.invert();
//              System.err.println("invert lvw = \n"+lvw);
                Point3f p0 = layout.transform(v);
//              Transform3D vwip = new Transform3D();
//              canvas.getVworldToImagePlate(vwip);
//              System.err.println("vwip=\n"+vwip);
//              t3d.mul(lvw);
                t3d.transform(p1);
//              scale.transform(p1);
                System.err.println("change location for vertex "+v+", transformGroup "+tg+" from "+p0+" to "+p1);
//              p1.set(p1.getX()*2,p1.getY()*2,p1.getZ()*2);
//              layout.setLocation(v, p1);

            }});

        PickSphereBehavior psb = new PickSphereBehavior(objRoot,canvas,bounds);

        PickVertexBehavior pvb = new PickVertexBehavior(objRoot,canvas,bounds,renderContext.getPickedVertexState());
        objTrans.addChild(pvb);
        pvb.addChangeListener(new ChangeListener() 
        {

            public void stateChanged(ChangeEvent e) 
            {
                for(V v : graph.getVertices()) 
                {
                    VertexGroup<V> vg = vertexMap.get(v);
                    Appearance look = redLook;
                    if(renderContext.getPickedVertexState().isPicked(v)) 
                    {
                        look = yellowLook;
                    }
                    Node node = vg.getShape();

                    if(node instanceof Primitive) 
                    {
                        ((Primitive)node).setAppearance(look);
                    }
                }

                }
        });

        //Shine it with two colored lights.
        Color3f lColor1 = new Color3f(.5f, .5f, .5f);
        Color3f lColor2 = new Color3f(1.0f, 1.0f, 1.0f);
        Vector3f lDir2  = new Vector3f(-1.0f, 0.0f, -1.0f);
        DirectionalLight lgt2 = new DirectionalLight(lColor2, lDir2);
        AmbientLight ambient = new AmbientLight(lColor1);
        lgt2.setInfluencingBounds(bounds);
        ambient.setInfluencingBounds(bounds);
        objRoot.addChild(lgt2);
        objRoot.addChild(ambient);

        // Let Java 3D perform optimizations on this scene graph.
        objRoot.compile();

//      VisRunner runner = new VisRunner((IterativeContext)elayout);
//      runner.relax();

        return objRoot;
    }

    public void setGraphLayout(Layout<V,E> inLayout) {

//      this.layout = inLayout;
        this.graph = inLayout.getGraph();
        BranchGroup branch = new BranchGroup();
        LayoutEventBroadcaster<V,E> elayout =
            new LayoutEventBroadcaster<V,E>(inLayout);
        this.layout = elayout;
        for(V v : graph.getVertices()) {
            VertexGroup<V> vg = new VertexGroup<V>(v, renderContext.getVertexShapeTransformer().transform(v));
            vg.setCapability(TransformGroup.ALLOW_TRANSFORM_WRITE);
            vg.setCapability(TransformGroup.ALLOW_TRANSFORM_READ);
            vertexMap.put(v, vg);
            branch.addChild(vg);
            String label = renderContext.getVertexStringer().transform(v);
            if(label != null) {
                String fontName = "Serif";
                Font3D f3d = new Font3D(new Font(fontName, Font.PLAIN, 2),
                        new FontExtrusion());
                Text3D txt = new Text3D(f3d, label, 
                        new Point3f(2f,2f,0));
                OrientedShape3D textShape = new OrientedShape3D();
                textShape.setGeometry(txt);
                textShape.setAppearance(grayLook);
//              textShape.setAlignmentAxis( 0.0f, 1.0f, 0.0f);
                textShape.setAlignmentMode(OrientedShape3D.ROTATE_ABOUT_POINT);
                textShape.setRotationPoint(new Point3f());
//              objScale.addChild( textShape );
//              BranchGroup bg = new BranchGroup();
//              bg.addChild(textShape);
//              branch.addChild(bg);



//              Text2D text = new Text2D(label+" more text here", new Color3f(0,0,0),"Serif",50,Font.BOLD);
                Transform3D tt = new Transform3D();
//              tt.setTranslation(new Vector3f(100,100,100));
                tt.setScale(5);
                TransformGroup tg = new TransformGroup(tt);
//              textShape.setGeometry(text);
                tg.addChild(textShape);
                BranchGroup bg = new BranchGroup();
                bg.addChild(tg);
//              branch.addChild(bg);
                vg.getLabelNode().addChild(bg);

            }

        }
        for(E edge : graph.getEdges()) {
            EdgeGroup<E> eg = 
                new EdgeGroup<E>(edge, renderContext.getEdgeShapeTransformer().transform(Context.<Graph<V,E>,E>getInstance(graph, edge)));
            eg.setCapability(TransformGroup.ALLOW_TRANSFORM_WRITE);
            eg.setCapability(TransformGroup.ALLOW_TRANSFORM_READ);
            edgeMap.put(edge, eg);
            branch.addChild(eg);
        }

//      System.err.println("branch is "+branch);
//      for(int i=0; i<branch.numChildren(); i++) {
//          System.err.println("branch child ["+i+"] is "+branch.getChild(i));
//      }

        objTrans.addChild(branch);
        elayout.addChangeListener(new ChangeListener() {

            public void stateChanged(ChangeEvent e) {
                for(V v : vertexMap.keySet()) {
                    Point3f p = VisualizationViewer.this.layout.transform(v);
                    Vector3f pv = new Vector3f(p.getX(), p.getY(), p.getZ());
                    Transform3D tx = new Transform3D();
                    tx.setTranslation(pv);
                    vertexMap.get(v).setTransform(tx);
                }

                for(E edge : graph.getEdges()) {
                    Pair<V> endpoints = graph.getEndpoints(edge);
                    V start = endpoints.getFirst();
                    V end = endpoints.getSecond();
                    EdgeGroup eg = edgeMap.get(edge);
                    eg.setEndpoints(layout.transform(start), layout.transform(end));
                }
            }});

        elayout.setSize(new BoundingSphere(new Point3d(), 200));
        elayout.initialize();
        VisRunner runner = new VisRunner((IterativeContext)elayout);
        runner.relax();
        try
        {
            Thread.sleep(1000);
        } catch (InterruptedException e1)
        {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }
        runner.stop();

//      for(int i=0; i<objTrans.numChildren(); i++) {
//          System.err.println("objTrans child ["+i+"] is "+objTrans.getChild(i));
//      }



    }

    public void setPickedVertexState(PickedState<V> pickedVertexState) {
        if(pickEventListener != null && this.pickedVertexState != null) {
            this.pickedVertexState.removeItemListener(pickEventListener);
        }
        this.pickedVertexState = pickedVertexState;
        this.renderContext.setPickedVertexState(pickedVertexState);
        if(pickEventListener == null) {
            pickEventListener = new ItemListener() {

                public void itemStateChanged(ItemEvent e) {
                    System.err.println(e.getItem()+" was picked");
                }
            };
        }
        pickedVertexState.addItemListener(pickEventListener);
    }

    public void setPickedEdgeState(PickedState<E> pickedEdgeState) {
        if(pickEventListener != null && this.pickedEdgeState != null) {
            this.pickedEdgeState.removeItemListener(pickEventListener);
        }
        this.pickedEdgeState = pickedEdgeState;
        this.renderContext.setPickedEdgeState(pickedEdgeState);
        if(pickEventListener == null) {
            pickEventListener = new ItemListener() {

                public void itemStateChanged(ItemEvent e) {
                    repaint();
                }
            };
        }
        pickedEdgeState.addItemListener(pickEventListener);
    }

    /**
     * @return the renderContext
     */
    public RenderContext<V, E> getRenderContext() {
        return renderContext;
    }
}

Here is graph builder

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.GraphicsConfiguration;
import java.awt.LayoutManager;
import java.util.HashMap;
import java.util.Map;
import java.util.Vector;

import javax.media.j3d.BoundingSphere;
import javax.media.j3d.Canvas3D;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.vecmath.Point3d;

import com.sun.j3d.utils.universe.SimpleUniverse;

import edu.uci.ics.jung.algorithms.layout3d.FRLayout;
import edu.uci.ics.jung.algorithms.layout3d.Layout;
import edu.uci.ics.jung.algorithms.layout3d.SpringLayout;
//import edu.uci.ics.jung.algorithms.layout.Layout;
import edu.uci.ics.jung.graph.Graph;
import edu.uci.ics.jung.graph.SparseMultigraph;
import edu.uci.ics.jung.visualization.BasicVisualizationServer;
import edu.uci.ics.jung.visualization.decorators.ToStringLabeller;
import edu.uci.ics.jung.visualization3d.VisualizationViewer;



public class GraphBuilder
{
    Graph<GraphNode, GraphEdge> g;
    Map<String, GraphNode> nodeList;
    VisualizationViewer<GraphNode, GraphEdge> vv;
    String root;
    private class GraphNode
    {
        String name;
        int i;
        GraphNode(int num)
        {
            i = num;
            name = Integer.toString(num);
        }

        GraphNode(String n)
        {
        name = n;
        }
        public String toString()
        {
            return name;
        }

    }

    private class GraphEdge
    {
        String name;
        GraphEdge()
        {

        }
    }

    GraphBuilder()
    {
        AccessGTDB demouser = new AccessGTDB();
        g = new SparseMultigraph<GraphNode, GraphEdge>();
        buildGraph(g);
        //buildTestGraph(g);

    }

    public JPanel getPanel()
    {
        AccessGTDB db = openDataBase();
        FRLayout<GraphNode, GraphEdge> fdl = new FRLayout<GraphNode, GraphEdge>(getBranchGraph(root, db));
        //Layout<GraphNode, GraphEdge> fdl = new SpringLayout<GraphNode, GraphEdge>(g);
        fdl.setSize(new BoundingSphere((new Point3d()), 1000));
        vv = new VisualizationViewer<GraphNode, GraphEdge>();
        vv.getRenderContext().setVertexStringer(new ToStringLabeller<GraphNode>());
        vv.setGraphLayout(fdl);
        vv.setPreferredSize(new Dimension(400, 600));
        closeDataBase(db);

        return vv;
    }

    public void pickedNodeCallBack()
    {

    }

    private void buildGraph(Graph<GraphNode, GraphEdge> gr)
    {
        int errorno;                            //  error flag

        AccessGTDB demouser = openDataBase();
        String brObj = demouser.getRootObject();        //  returns the name of the root object for currently selected database
        root = brObj;   //main root node for this database, need to keep track of it for access
        GraphNode tmpNode = new GraphNode(brObj); 
        nodeList = new HashMap<String, GraphNode>();
        nodeList.put(brObj, tmpNode);
        gr.addVertex(tmpNode);

        gr = buildFullGraph(gr, brObj, demouser);

        closeDataBase(demouser);

    }

    /*private Graph<GraphNode, GraphEdge> buildTestGraph(Graph<GraphNode, GraphEdge> gr)
    {
        nodeList = new HashMap<String, GraphNode>();

        for(int i = 0; i < 4; i++)
        {
            GraphNode tmp = new GraphNode(i);
            gr.addVertex(tmp);
            nodeList.put(Integer.toString(i), tmp);
        }

        for(int k = 0; k < 3; k++)
        {
            GraphEdge tmp = new GraphEdge();
            gr.addEdge(tmp, nodeList.get(Integer.toString(k)), nodeList.get(Integer.toString(k+1)));
        }
        GraphEdge tmp = new GraphEdge();
        gr.addEdge(tmp, nodeList.get(Integer.toString(3)), nodeList.get(Integer.toString(1)));

        return gr;
    }
    */
    private Graph<GraphNode, GraphEdge> buildFullGraph(Graph<GraphNode, GraphEdge> gr, String brObj, AccessGTDB demouser)
    {

        GraphNode brNode = nodeList.get(brObj);
        String branchList[];                              //  array to receive the list of all branches
        branchList = demouser.getObjectTree( brObj );     //  get all branches off the selected object
        int bl = branchList.length;                       //  length of the returned array

        //if leaf return
        if(bl <= 1)
        {
            return gr;
        }

        for ( int j=1; j < bl; j++)                       //  loop through all the branches
        {
            GraphNode tmpNode = new GraphNode(branchList[j]);
            nodeList.put(branchList[j], tmpNode);
            gr.addVertex(tmpNode);
            GraphEdge tmpEdge = new GraphEdge();
            gr.addEdge(tmpEdge, brNode, tmpNode);
            gr = buildFullGraph(gr, branchList[j], demouser);
        }

        return gr;                                         
    }

    private Graph<GraphNode, GraphEdge> getBranchGraph(String brObj, AccessGTDB demouser)
    {
        Graph<GraphNode, GraphEdge> toDraw = new SparseMultigraph<GraphNode, GraphEdge>();
        GraphNode brNode = nodeList.get(brObj);
        String branchList[];                              //  array to receive the list of all branches
        branchList = demouser.getObjectTree( brObj );     //  get all branches off the selected object
        int bl = branchList.length;                       //  length of the returned array

        for ( int j=1; j < bl; j++)                       //  loop through all the branches
        {
            GraphNode tmpNode = new GraphNode(branchList[j]);
            toDraw.addVertex(tmpNode);
            GraphEdge tmpEdge = new GraphEdge();
            toDraw.addEdge(tmpEdge, brNode, tmpNode);
        }

        return toDraw;                                         
    }

    private AccessGTDB openDataBase()
    {
        int errorno;                            //  error flag

        AccessGTDB demouser = new AccessGTDB();
        String DBList[];                            //  array that will contain the list of possible databases (demo only has one)
        DBList = demouser.getDatabases();           //  call to retrieve the list of possible databases
        int nl = DBList.length;

        errorno = demouser.selectDatabase( DBList[0] );     //  select the chosen database
        errorno = demouser.serverLogin( "localhost", "demouser", "********" );
        if ( errorno != 0 )                      //  verify server system was found and login was valid
        {
            System.out.printf ("\n");
            System.out.printf ("server login error number = %d\n",errorno);
            System.out.printf ("Program Terminated.\n");
            System.exit( errorno );
        }

            int tdbsize = -1;
        demouser.setTempDBSize ( tdbsize );

        errorno = demouser.openDatabase( "dbengine", "dbuser", "********" );     //  database login; for demo all values are ingored so can be anything

        if ( errorno != 0 )                      //  verify database engine was found and login was valid
        {
            System.out.printf ("\n");
            System.out.printf ("database open error number = %d\n",errorno);
            System.out.printf ("Program Terminated.\n");
            System.exit( errorno );
        }

        return demouser;
    }

    private void closeDataBase(AccessGTDB demouser)
    {
        int errorno;
        errorno = demouser.closeDatabase();                  //  log out of the database

        if ( errorno != 0 )                                  //  just make sure everything went ok
        {
            System.out.printf ("\n");
            System.out.printf ("database close error number = %d\n",errorno);
            System.out.printf ("Program Terminated.\n");
            System.exit( errorno );
        }
        // serverLogout
        //  while not technically needed, log off the server hosting the database (for localhost, this merely erases login name and password)
        errorno = demouser.serverLogout();                    //  log off the database server

          if ( errorno != 0 )                                   //  just make sure everything went ok
              {
              System.out.printf ("\n");
              System.out.printf ("server logout error number = %d\n",errorno);
              System.out.printf ("Program Terminated.\n");
              System.exit( errorno );
          }

    }
}

When I try to define GraphBuilder in VisualizationViewer, eclipse tells me GraphBuilder cannot be resolved to a type. Yet I can right click it and go to the definition. Am i missing something obvious here? Thanks for the help!

Addendum, I've cut out all classified material here, that does not have an effect on the problem.

Simply defining GraphBuilder as a class variable in VisualizationViewer is causing this error on line 69.

Answer 1

I would recommend you read some Java tutorials like:

http://download.oracle.com/javase/tutorial/getStarted/application/index.html

Regarding your problem, I'm not sure where to start to solve your problem, but I think you want to do something like this

package demo.apackagename;

public class ClassA {

   public static void main(String [ ] args){
      ClassA a = new ClassA();
      ClassB b = new ClassB(a);
      b.methodBThatCallsA();
   }

   public void methodA() {
      System.err.println("methodA");
   }
}

Note that main() is the entry point of the application:

package demo.apackagename;

public class ClassB {
   private ClassA a = null;
   public ClassB(ClassA a_) {
      this.a = a_;
   }

   public void methodBThatCallsA() {
      System.out.println("Class B");
      a.methodA();
   }
}

Answer 2

Obsolete Answer

Filling in the "blanks": Your code looks like this now:

import things.*;

class MyClass{
    MyClass(){
        SpecialClass x = new SpecialClass(this); // totally fails.
    }
}

class SpecialClass{
    SpecialClass(){
        MyClass y;
    }
}

Why totally fails? Because SpecialClass doesn't have a constructor that takes a MyClass lol!

Also, like, this doesn't like "exist" before the constructor finishes dude.

Answer 3

I might be a bit sleepy here but I think you need to define the constructor of GraphBuilder as

public GraphBuilder(){
}

if you leave it as

GraphBuilder(){
}

the scope of a constructor without the visibility keyword is only of its package.

Answer 4

您需要在VisualizationViewer文件中导入GraphBuilder 。