java Eclipse 无法解析类型，但类在构建路径上
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时间：2020-10-30 15:35:53 来源:igfitidea点击:
Eclipse cannot resolve type but class is on build path
提问by Alan
I have done about 4 hours worth of internet hunting and have hit my limit. Hopefully you folks can help.
我已经完成了大约 4 小时的互联网搜索，并且达到了我的极限。希望各位大侠帮忙。
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.
我有一个项目，其中包含一个包含一些源代码的包。我还有我的主要源文件夹，其中也包含这个包。
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:
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，并且有效。我的主源文件夹中的一个源文件实例化了在此源文件中定义的对象。我需要将此对象传递给调用对象的引用才能回调。因此，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;
}
}
Here is graph builder
这是图形生成器
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 );
}
}
}
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!
当我尝试在 VisualizationViewer 中定义 GraphBuilder 时，eclipse 告诉我 GraphBuilder 无法解析为类型。但是我可以右键单击它并转到定义。我在这里遗漏了一些明显的东西吗？谢谢您的帮助！
Addendum, I've cut out all classified material here, that does not have an effect on the problem.
附录，我在这里删掉了所有机密材料，这对问题没有影响。
Simply defining GraphBuilder as a class variable in VisualizationViewer is causing this error on line 69.
简单地将 GraphBuilder 定义为 VisualizationViewer 中的类变量会导致第 69 行出现此错误。
回答by Jason Rogers
I would recommend you read some Java tutorials like:
我建议您阅读一些 Java 教程，例如：
http://download.oracle.com/javase/tutorial/getStarted/application/index.html
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
关于你的问题，我不确定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");
}
}
Note that main()is the entry point of the application:
请注意，这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();
}
}
回答by trutheality
Obsolete Answer
过时的答案
Filling in the "blanks": Your code looks like this now:
填写“空白”：您的代码现在如下所示：
import things.*;
class MyClass{
MyClass(){
SpecialClass x = new SpecialClass(this); // totally fails.
}
}
class SpecialClass{
SpecialClass(){
MyClass y;
}
}
Why totally fails? Because SpecialClassdoesn't have a constructor that takes a MyClasslol!
为什么完全失败？因为SpecialClass没有一个需要MyClass大声笑的构造函数！
Also, like, thisdoesn't like "exist" before the constructor finishes dude.
另外，this在构造函数完成之前，不喜欢“存在”。
回答by Jason Rogers
I might be a bit sleepy here but I think you need to define the constructor of GraphBuilder as
我可能在这里有点困，但我认为您需要将 GraphBuilder 的构造函数定义为
public GraphBuilder(){
}
if you leave it as
如果你把它作为
GraphBuilder(){
}
the scope of a constructor without the visibility keyword is only of its package.
没有可见性关键字的构造函数的范围仅是它的包。
回答by trutheality
You need to import GraphBuilderin your VisualizationViewerfile.
您需要导入GraphBuilder您的VisualizationViewer文件。
