我已经完成了大约4个小时的网络搜索并达到了极限。希望你们大家可以提供帮助。
我有一个包含一些源代码的包的项目。我也有我的主源文件夹，其中也包含此包。
在包目录中，我定义了源文件，而不是类文件。我使用这个目录作为源文件夹，这是有效的。我的主源文件夹中的一个源文件实例化了此源文件中定义的对象。我需要传递这个对象对调用对象的引用才能回调。所以，例如：
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;
}
}
这是图表构建器
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 );
}
}
}
当我尝试在VisualizationViewer中定义GraphBuilder时，eclipse告诉我GraphBuilder无法解析为某种类型。然而，我可以右键单击它并转到定义。我错过了一些明显的东西吗？谢谢你的帮助！
附录，我在这里删除了所有分类材料，这对问题没有影响。
在VisualizationViewer中简单地将GraphBuilder定义为类变量会导致第69行出现此错误。
答案 0 :(得分：2)
我建议你阅读一些Java教程，如：
http://download.oracle.com/javase/tutorial/getStarted/application/index.html
关于你的问题，我不知道从哪里开始解决你的问题，但我认为你想做这样的事情
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");
}
}
请注意，main()是应用程序的入口点：
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();
}
}
答案 1 :(得分：1)
填写“空白”：您的代码现在看起来像这样：
import things.*;
class MyClass{
MyClass(){
SpecialClass x = new SpecialClass(this); // totally fails.
}
}
class SpecialClass{
SpecialClass(){
MyClass y;
}
}
为什么完全失败？因为SpecialClass没有构造函数需要MyClass lol！
此外，在构造函数完成dude之前， this不喜欢“存在”。
答案 2 :(得分：1)
我可能在这里有点困，但我认为你需要将GraphBuilder的构造函数定义为
public GraphBuilder(){
}
如果你把它留作
GraphBuilder(){
}
没有visibility关键字的构造函数的范围只是它的包。
答案 3 :(得分：0)
您需要在GraphBuilder文件中导入VisualizationViewer。