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Force relayout of Java FX Chart programatically

I have made programmatic changes to a Java FX Line Chart and I need a programmatic way to force a re-layout of the JavaFX Chart to occur. This question has been asked/answered before but not in my context.
I have tried the typical methods that have been presented as answers to this question (see complete, minimal example code below with in-line attempts at solving the problem). None of the typical solutions to this problem work.
Specifically (sp is a StackPane):
sp.requestLayout(); // does not work
and
sp.applyCss();
sp.layout(); // does not work
placing the above code in a .runLater() does not work.
I know that my changes are present in the chart because
(1) When I resize the chart by hand my changes suddenly appear
(2) When I use the "resize" method programmatically my changes appear BUT there is a different error (plus only parent nodes are supposed to use the "resize" method - not us programmers).
Below is a minimal complete set of code which reproduces the problem. When you run the code I programmatically change one of the data points to be larger when the chart is displayed. This resize works correctly. When you right-click on the chart a context menu appears with one choice ("Resize ALL the points"). When you select that single option my code resizes all the points - BUT - none of the data points are resized visually. If I resize the chart manually by dragging a side, the chart does a re-layout and all the data node sizes immediately visually change to the correct size (The size I programmatically set them to).
How can I force the re-layout to occur programmatically that I can force to occur manually? I would NOT like to do a hack (like programmatically set the stage size to be 1 pixel smaller and then set it one pixel larger).
Note: I have read that attempts to do a requestLayout() while a layout is in progress will be ignored so perhaps something like that is going on. I think a requestLayout() inside of a runLater() would fix the issue of an ongoing Layout() but that has not worked either.
Update: Scaling was suggested as an alternative to changing the StackPane size. This solution may be helpful to some but not to me. The Look and Feel of scaling a symbol is different than the look and feel of changing the regions size and allowing the "symbol" to grow into that size.
As a complete aside this is my first stackoverflow post. So thanks for all the previous examples a I have used from this forum in the past & thanks in advance for the answer to this problem.
import java.util.Random;
import javafx.application.Application;
import javafx.application.Platform;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.scene.Group;
import javafx.scene.Node;
import javafx.scene.Scene;
import javafx.scene.chart.LineChart;
import javafx.scene.chart.LineChart.SortingPolicy;
import javafx.scene.chart.NumberAxis;
import javafx.scene.chart.XYChart.Data;
import javafx.scene.chart.XYChart.Series;
import javafx.scene.control.ContextMenu;
import javafx.scene.control.MenuItem;
import javafx.scene.input.MouseButton;
import javafx.scene.input.MouseEvent;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;
public class dummy extends Application {
#Override
public void start(Stage primaryStage) {
Random random = new Random();
final NumberAxis xAxis = new NumberAxis();
final NumberAxis yAxis = new NumberAxis();
xAxis.setLabel("X");
yAxis.setLabel("Y");
final LineChart<Number,Number> lineChart = new LineChart<Number,Number>(xAxis,yAxis);
Series<Number,Number> series = new Series<Number,Number>();
series.setName("Dummy Data");
// Generate data
double x = 0.0;
double y = 0.0;
for (int i = 0; i < 10; i++) {
Data<Number,Number> data = new Data(x += random.nextDouble(), y+=random.nextDouble());
series.getData().add(data);
}
lineChart.getData().add(series);
lineChart.setTitle("Random Data");
lineChart.setAxisSortingPolicy(SortingPolicy.NONE);
Scene scene = new Scene(lineChart,1200,600);
Stage stage = new Stage();
stage.setScene(scene);
stage.show();
// This resizes the first data point directly (this resize is displayed correctly when program is run)
Node node = series.getData().get(0).getNode();
setSize((StackPane)node,20);
// The context menu is invoked by a right click on the line Chart. It will resize the data point based on a context menu pick
// this resize does not work....unless I resize the window manually which causes a refresh/re-layout of the chart).
lineChart.setOnMouseClicked(new EventHandler<MouseEvent>() {
#Override public void handle(MouseEvent mouseEvent) {
if (MouseButton.SECONDARY.equals(mouseEvent.getButton())) {
Scene scene = ((Node)mouseEvent.getSource()).getScene();
ContextMenu menu = createMenu(lineChart);
menu.show(scene.getWindow(), mouseEvent.getScreenX(), mouseEvent.getScreenY());
}
}
});
}
private void setSize(StackPane sp, int size) {
sp.setMinSize(size, size);
sp.setMaxSize(size, size);
sp.setPrefSize(size, size);
}
// this creates a context menu that will allow you to resize all the data point nodes
private ContextMenu createMenu(LineChart<Number,Number> lineChart) {
final ContextMenu contextMenu = new ContextMenu();
final MenuItem resize = new MenuItem("Resize ALL the points");
resize.setOnAction(new EventHandler<ActionEvent>() {
#Override public void handle(ActionEvent event) {
for (Series<Number, Number> series : lineChart.getData()) {
for (Data<Number, Number> data : series.getData()) {
StackPane sp = (StackPane)data.getNode();
setSize (sp, 20);
// The above resizes do not take effect unless/until I manually resize the chart.
// the following two calls do not do anything;
sp.applyCss();
sp.layout();
// The request to layout the node does nothing
sp.requestLayout();
// Doing both of the above as runLaters does nothing
Platform.runLater(()->{sp.applyCss();sp.layout();});
Platform.runLater(()->{sp.requestLayout();});
// Going after the parent does nothing either
Group group = (Group)sp.getParent();
group.applyCss();
group.layout();
group.requestLayout();
// Going after the parent in a run later does nothing
Platform.runLater(()->{
group.applyCss();
group.layout();
group.requestLayout();
});
// note... doing a resize [commented out below] will work-ish.
// The documentation says NOT to use it thought that as it is for internal use only.
// By work-ish, the data points are enlarged BUT they are no longer centered on the data point
// When I resize the stage they get centered again - so this "solves" my original problem but causes a different problem
////////////////////////////////////
// sp.resize(20, 20); // Uncomment this line to see how it mostly works but introduces a new issue
////////////////////////////////////
}
}
}
});
contextMenu.getItems().add(resize);
return contextMenu;
}
public static void main(String[] args) {
Application.launch(args);
}
}

You can force a relayout by using e.g. an inner class
class LineChartX<X, Y> extends LineChart<X, Y>
{
public LineChartX(#NamedArg("xAxis") Axis<X> xAxis, #NamedArg("yAxis") Axis<Y> yAxis)
{
super(xAxis, yAxis);
}
#Override
public void layoutPlotChildren()
{
super.layoutPlotChildren();
}
}
and calling
lineChart.layoutPlotChildren();
in your menu action.
Simple one-line Solution:
nodes in LineChart scene graph have these parent-child relationships:
Pane chartContent - Group plotArea - Group plotContent - Path seriesLine;
layout requests for Group plotArea, defined in class XYChart, are suppressed:
private final Group plotArea = new Group(){
#Override public void requestLayout() {} // suppress layout requests
};
but Pane chartContent accepts layout requests:
Node node = series.getNode();
if (node instanceof Path) {
Path seriesLine = (Path) node;
Parent parent = seriesLine.getParent();
if (parent instanceof Group) {
Group plotContent = (Group) parent;
parent = plotContent.getParent();
if (parent instanceof Group) {
Group plotArea = (Group) parent;
parent = plotArea.getParent();
if (parent instanceof Pane) {
Pane chartContent = (Pane) parent;
chartContent.requestLayout();
}
}
}
}
so relayout of your chart can be forced by addding this single line
series.getNode().getParent().getParent().getParent().requestLayout();
to the end of your menu action handler.

You don't need to cast that node into a StackPane and set sizes. You need to use the setScaleX() and setScaleY() Methods
Node node = series.getData().get(0).getNode();
node.setScaleX(20);
node.setScaleY(20);
#Override
public void handle(ActionEvent event) {
for (Series<Number, Number> series : lineChart.getData()) {
for (Data<Number, Number> data : series.getData()) {
Node node = data.getNode();
node.setScaleY(20);
node.setScaleX(20);
}
}
}

#c0der posted a solution in comment form to my original post which worked but produced a runtime warning (in Eclipse). His solution was to add a dummy style sheet at the lineChart level with lineChart.getStylesheets().add(""); after the for loops ended. This code produced the warning "Apr 28, 2020 9:01:12 AM com.sun.javafx.css.StyleManager loadStylesheetUnPrivileged WARNING: Resource "" not found."
What did work without causing a run-time warning was to load an empty .css file and add it as a StyleSheet:
lineChart.getStylesheets().add(CSS.class.getResource("Empty.css").toExternalForm());
// note: I keep my .css resource files at the same location as my CSS class
// which is why I have the code "CSS.class" above
This one line solution worked once but I doubted it would work multiple times. I tested it to by increasing the size of the StackPane by 5 for each successive time "Resize ALL the points" was selected (in my dummy code above). Sure enough, it only worked the first time.
However, I added the no-op code lineChart.getStylesheets().replaceAll((s)->s+" "); before that one line solution and now it works multiple times in a row.
No matter how many times I executed the two lines of code
lineChart.getStylesheets().replaceAll((s)->s+" ");
lineChart.getStylesheets().add(CSS.class.getResource("Empty.css").toExternalForm()); `
it (1) worked and (2) The size of the list of lineChart StyleSheets did not grow beyond a size of 1. So a solution with a mystery.
Note: if you have an existing style sheet (I did not in my dummy example above) lineChart.getStylesheets().replaceAll((s)->s+" "); by itself may work as well. For some reason lineChart.getStylesheets().replaceAll((s)->s); without adding the " " on the end did not work.
Note: I originally thought I would have to code up a toggle solution to add Empty.css and the remove Empty.css with alternate calls but that proved unnecessary.
Bottom Line: if you have an existing StyleSheet lineChart.getStylesheets().replaceAll((s)->s+" "); works. If you do not have an existing StyleSheet adding an empty .css file as a StyleSheet in conjunction with the above replaceAll works.
Thanks again to #c0der for his original approach.

Type graph does not take parameters

In order to create a multigraph I used the JUNG library but while coding i received this problem "type graph does not take parameters" and i can't find any solution to solve the problem in this code :
import edu.uci.ics.jung.algorithms.layout.CircleLayout;
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.layout.*;
import java.awt.Dimension;
import javax.swing.JFrame;
public class Simpleg {
Graph<Integer, String> g;
/** Creates a new instance of SimpleGraphView */
public Simpleg() {
// Graph<V, E> where V is the type of the vertices and E is the type of the edges
g = new SparseMultigraph<Integer, String>();
// Add some vertices. From above we defined these to be type Integer.
g.addVertex((Integer)1);
g.addVertex((Integer)2);
g.addVertex((Integer)3);
// Note that the default is for undirected edges, our Edges are Strings.
g.addEdge("Edge-A", 1, 2); // Note that Java 1.5 auto-boxes primitives
g.addEdge("Edge-B", 2, 3);
}
public static void main(String[] args) {
Simpleg sgv = new Simpleg(); //We create our graph in here
// The Layout<V, E> is parameterized by the vertex and edge types
Layout<Integer, String> layout = new CircleLayout(sgv.g);
layout.setSize(new Dimension(300,300)); // sets the initial size of the layout space
// The BasicVisualizationServer<V,E> is parameterized by the vertex and edge types
BasicVisualizationServer<Integer,String> vv = new BasicVisualizationServer<Integer,String>(layout);
vv.setPreferredSize(new Dimension(350,350)); //Sets the viewing area size
JFrame frame = new JFrame("Simple Graph View");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(vv);
frame.pack();
frame.setVisible(true);
}
}

It turns out the compiler - netbeans in my case - was pointing towards the wrong jar. I think Graph is available in JUNG 2.0
http://www.grotto-networking.com/JUNG/JUNG2-Tutorial.pdf
My compiler was pointing at some lower version which I removed and added jung-api-2.0.1.jar

How to queue some part of a program

I apologize for the topic headline, it might not exactly express my thought but i'll give it a try. If someone knows what's the better headline, please suggest an edit.
So i'd like to create rectangles and give values for them after the button has been pressed. Everything's plain and simple if i know how many rectangles i want to create. Here's where thing gets complicated - i get the rectangle count after i've pressed the button.
I'll explain with an example, so it's a bit more clear:
final ArrayList rectList = new ArrayList();
btn.setOnAction(new EventHandler<ActionEvent>() {
public void handle(final ActionEvent event) {
ArrayList getFromMethodAnArrayList = methodWhichReturnsAnArrayList();
for (int i = 0; i<getFromMethodAnArrayList.size();i++){
rectList.add(new Rectangle(0,0,0,30));
}
}
});
HBox box1 = new HBox(1);
for (int i = 0; i<rectList.size();i++){
box1.getChildren().add(rectList.get(i));
}
This code gives an error because when first loaded the rectList is empty. How could i queue adding elements into HBox, so it would be performed after the rectList has been valued.

Recommendation
You don't need a queue here and you don't need to multi-thread either, at least as you have currently described your question - additional requirements on the implementation could imply that the use of both of those things are necessary.
Sample code
What the sample code does is define a source of items which are model data for something you want to display. When you click on the create button, it will generate a random number of new items with random data values for each item. These items will be placed in a queue and a subsequent routine will take the items from the queue, read their data values and create appropriate visual representations (rectangles) for the item data. It uses a queue data structure, but a simple array or list would have worked just fine.
import javafx.application.Application;
import javafx.scene.*;
import javafx.scene.control.*;
import javafx.scene.layout.*;
import javafx.scene.paint.Color;
import javafx.scene.shape.Rectangle;
import javafx.stage.Stage;
import java.util.ArrayDeque;
import java.util.Queue;
import java.util.Random;
// java 8 code
public class RectangleAddition extends Application {
private final Random random = new Random(42);
public static void main(String[] args) {
launch(args);
}
public void start(Stage stage) {
FlowPane flow = createItemContainer();
ScrollPane scroll = makeContainerScrollable(flow);
ItemSource itemSource = new ItemSource();
Button create = createItemControl(flow, scroll, itemSource);
VBox layout = createLayout(create, scroll);
Scene scene = new Scene(layout);
stage.setScene(scene);
stage.show();
}
private FlowPane createItemContainer() {
FlowPane flow = new FlowPane();
flow.setHgap(5);
flow.setVgap(5);
return flow;
}
/**
* The control will
* retrieve items from the source,
* add them to the scrollable pane,
* scroll the pane to the bottom on each addition.
*/
private Button createItemControl(Pane flow, ScrollPane scroll, ItemSource itemSource) {
Button create = new Button("Create Rectangles (keep pressing to create more)");
create.setOnAction(event -> {
addRectangles(flow, itemSource);
scroll.setVvalue(scroll.getVmax());
});
return create;
}
private VBox createLayout(Button create, ScrollPane scroll) {
VBox layout = new VBox(10, create, scroll);
layout.setStyle("-fx-padding: 10px;");
layout.setPrefSize(300, 300);
VBox.setVgrow(scroll, Priority.ALWAYS);
create.setMinHeight(Button.USE_PREF_SIZE);
return layout;
}
/**
* fetches some items from the source,
* creates rectangle nodes for them
* adds them to the container.
*/
private void addRectangles(Pane container, ItemSource itemSource) {
Queue<Item> items = itemSource.fetchNextItems();
while (!items.isEmpty()) {
Item item = items.remove();
Node rectangle = createRectangle(item);
container.getChildren().add(rectangle);
}
}
private Rectangle createRectangle(Item item) {
Rectangle rectangle = new Rectangle(item.size, item.size, item.color);
rectangle.setRotate(item.rotation);
return rectangle;
}
private ScrollPane makeContainerScrollable(FlowPane flow) {
ScrollPane scroll = new ScrollPane(flow);
scroll.setFitToWidth(true);
scroll.setMaxSize(Double.MAX_VALUE, Double.MAX_VALUE);
return scroll;
}
/** some model data for application items */
class Item {
// item will be colored according to rgb values from the (inclusive) range
// MIN_COLOR_VALUE to MIN_COLOR_VALUE + COLOR_RANGE - 1
private static final int MIN_COLOR_VALUE = 50;
private static final int COLOR_RANGE = 201;
// item will be sized from the (inclusive) range
// MIN_SIZE to MIN_SIZE + SIZE_RANGE - 1
private static final int MIN_SIZE = 5;
private static final int SIZE_RANGE = 21;
// item will be (z-axis) rotated from the (inclusive) range
// - ROTATE_SCOPE to + ROTATE_SCOPE
private static final int ROTATE_SCOPE = 10;
private Color color;
private int size;
private int rotation;
public Item() {
color = Color.rgb(
createColorComponent(),
createColorComponent(),
createColorComponent()
);
size = random.nextInt(SIZE_RANGE) + MIN_SIZE;
rotation = random.nextInt(ROTATE_SCOPE * 2 + 1) - ROTATE_SCOPE;
}
private int createColorComponent() {
return random.nextInt(COLOR_RANGE) + MIN_COLOR_VALUE;
}
}
/** a never-ending source of new items fetched in batches */
class ItemSource {
// will fetch between 1 and MAX_NUM_ITEMS_PER_FETCH (inclusive) items on each fetch call.
private static final int MAX_NUM_ITEMS_PER_FETCH = 5;
public Queue<Item> fetchNextItems() {
int numItems = random.nextInt(MAX_NUM_ITEMS_PER_FETCH) + 1;
Queue<Item> queue = new ArrayDeque<>(numItems);
for (int i = 0; i < numItems; i++) {
queue.add(new Item());
}
return queue;
}
}
}
Thoughts On Multithreading
Where you might want a different implementation which does actually use multi-threading is if the item creation or fetching from the item source takes a long time. For example you need to read the item data from a network, database or very large file. If you don't multi-thread such things, then you will end up freezing the UI while it waits for the I/O to complete. A general rule is if the operation you are performing will finish in less than a sixtieth of a millisecond, then you can do it on the JavaFX UI thread without any issue as there will be no visible lag and stuttering in the UI, but if it takes longer than that then you should use concurrency utilities (which are more tricky to use than single-threaded code).
Java has numerous threading mechanisms, which can be used, but you in many cases, using the JavaFX specific concurrency extensions is the best way to integrate multi-threaded code into your JavaFX application.
The appropriate concurrency utility to use usually would be the JavaFX Task or Service interfaces if you are doing this on demand from the UI. You can read the documentation for these facilities which demonstrates sample code for doing things like "a task which returns partial results" (which is a bit similar to your question).
If the thing which provides the items to be consumed is some background long running network task to which items are pushed, rather than pulled on demand, then running it in it's own thread and calling back into the JavaFX to signal a UI update via platform.runLater() is the way to go. Another data structure which can aid in such cases is a BlockingQueue as demonstrated in this multi-chart creation code - but that is quite a sophisticated solution.
I guess part of my point is that you may not need to use these concurrency utilities for your situation, you need to evaluate it on a case by case basis and use the most appropriate solution.

I think you can simplify your code quite a bit here by getting rid of the ArrayList and populating box1 when the button event happens:
final HBox box1 = new HBox(1);
btn.setOnAction(new EventHandler<ActionEvent>() {
public void handle(final ActionEvent event) {
ArrayList getFromMethodAnArrayList = methodWhichReturnsAnArrayList();
for (int i = 0; i<getFromMethodAnArrayList.size();i++){
box1.getChildren().add(new Rectangle(0,0,0,30));
}
}
});
If it is concurrency that you are interested in, it would be good to read Concurrency in JavaFX, although I don't think that is the right solution for the question you posted.

Using rectangles to simulate straight line motion of an object

I am relatively new to Java and have been trying to simulate the motion of an object (say a car) on a straight path.
I want my object to move in steps in the output, instead of appearing just at the last point of the line.
I have used 2 classes :Veh.java - the vehicle object and SimuFrame.java - to create the simulation environment.
I have referred to some online tutorials for ideas: http://www.newthinktank.com/2012/07/java-video-tutorial-52/ (This simulates the asteroids game. Howeer I want my object to move in a straight line instead of in a random direction)
Please help me understand where I am wrong and what to do next..
Thanks a lot.
Here's my code:
import java.awt.*;
import java.awt.event.*;
public class Veh extends Rectangle{
int uLeftX, uLeftY; //upper LH Position for Rectangle
static int height = 20;
static int width = 20;
int[] pathCoords=new int[1000];
int startPosY; // start position of the objet - anywhere on the left bounday of the frame.
int goalPosY; // end position of the objet - anywhere on the right boundary of the frame.
//Constructor to Create a new Veh
public Veh(int startPosY,int goalPosY){
//Create a new rectangle vehicle from super class constructor
super(0, startPosY, height, width);
this.startPosY=startPosY;
this.goalPosY=goalPosY;
this.pathCoords = Pathmove();
}
//Calculating the 1000 points on the line joining (0,startPosY) and (goalPosY,999)
int[] Pathmove(){
//Slope calculation
float s=(float)(this.goalPosY-this.startPosY)/999;
pathCoords[0]=this.startPosY;
System.out.println("First xy pair is: 0," +this.pathCoords[0]);
for(int m=1; m<1000; m++){
pathCoords[m]= (int)(m*s)-(int)((m-1)*s)+ pathCoords[m-1];
}
return pathCoords;
}
//Function to move the Reactangular object along the line using the Y coordinate values from Pathmove()
void move(){
int[] a = (int[])this.pathCoords.clone();
for (int c=0; c<a.length;c++){
this.setLocation(c,a[c]);
}
}
}
This is the code for creating the simulation environment.
import javax.swing.*;
import java.awt.*;
import java.util.*;
import java.util.concurrent.ScheduledThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
public class SimuFrame extends JFrame{
public static int frameWidth=1000;
public static int frameHeight=1000;
public static void main(String[] args){
new SimuFrame();
}
public SimuFrame(){
this.setSize(frameWidth,frameHeight);
this.setTitle("Path Planning Results");
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
SimuObject SO=new SimuObject();
this.add(SO);
// Used to execute code after a given delay
// The attribute is corePoolSize - the number of threads to keep in
// the pool, even if they are idle
ScheduledThreadPoolExecutor executor= new ScheduledThreadPoolExecutor(5);
executor.scheduleAtFixedRate(new RepaintTheFrame(this), 0L, 20L, TimeUnit.MILLISECONDS);
this.setVisible(true);
}
}
// Class implements the runnable interface
// By creating this thread I want to continually redraw the screen
// while other code continues to execute
class RepaintTheFrame implements Runnable{
SimuFrame theFrame;
public RepaintTheFrame(SimuFrame theFrame){
}
#Override
public void run() {
theFrame.repaint();
}
}
class SimuObject extends JComponent{
//Holds every Veh created
public ArrayList<Veh> vehs=new ArrayList<Veh>();
public SimuObject(){
int startPosY = (int)(Math.random()*999);
int goalPosY = (int)(Math.random()*999);
vehs.add(new Veh(startPosY,goalPosY));
}
public void paint(Graphics g){
// Allows me to make many settings changes in regards to graphics
Graphics2D graphicSettings = (Graphics2D)g;
// Draw a background that is as big as the Simu board
graphicSettings.setColor(Color.WHITE);
graphicSettings.fillRect(0, 0, getWidth(), getHeight());
// Set rendering rules
graphicSettings.setRenderingHint( RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
// Set the drawing color to red
graphicSettings.setPaint( Color.RED);
// Cycle through all of the Rock objects
for(Veh veh : vehs){
// Move the vehicle
veh.move();
graphicSettings.draw(veh);
}
}
}

You have a number of problems in your code:
You have a (swallowed) NullPointerException (NPE) in RepaintTheFrame.run(), which causes ScheduledThreadPoolExecutor.scheduleAtFixedRate() to run only once, per scheduleAtFixedRate()'s javadoc.
You are moving your car in JComponent.paint().
In any graphical framework, the repaint will be called automatically by the framework, usually on an OS event, e.g. moving the window, moving the mouse over the window, etc.
Your paint() method should only draw. It should not modify your domain model.
Your move() method always ends up with the vehicle at the end. That's probably not your intent. You probably want your move() method to merely increment the car's position.

Moving from a start value to an end value in steps is called interpolation. You want linear interpolation specifically here. Its one of the easiest to grasp.
This page will be of great assistance to you.
Without getting fancy with interpolation, you could just change your move routine like so:
int index =0;
void move(){
//int[] a = (int[])this.pathCoords.clone();
if(index<this.pathCoords.length)
this.setLocation(c,pathCoords[index]);
index+=1;
}
Not sure why you were cloning the array there. It probably isn't necessary.

Jmonkey engine 3.0 Drawing points

How can I draw a 3D-point (or point sprite) in 3D space?
There is no documentation for drawing a point in JMonkey Engine site or anywhere else. Just a single point. Then updating the coordinates. No color, just a dot in 3D space.

A point (as opposed to a sphere) can be created using a mesh in which you directly set its buffers (or technically buffer; since a points mesh doesn't require an index buffer as other more complex meshes require. See How can I draw a straight line in the JMonkey Engine library). Mesh creation is documented here.
An example of creating points in 3D space using a mesh is below:
import com.jme3.app.SimpleApplication;
import com.jme3.material.Material;
import com.jme3.math.*;
import com.jme3.renderer.RenderManager;
import com.jme3.scene.*;
import com.jme3.util.BufferUtils;
public class Main extends SimpleApplication {
public static void main(String[] args) {
Main app = new Main();
app.start();
}
#Override
public void simpleInitApp() {
Vector3f[] lineVerticies=new Vector3f[5];
lineVerticies[0]=new Vector3f(2,0,0);
lineVerticies[1]=new Vector3f(-1,0,1);
lineVerticies[2]=new Vector3f(0,1,1);
lineVerticies[3]=new Vector3f(1,1,1);
lineVerticies[4]=new Vector3f(1,4,0);
plotPoints(lineVerticies,ColorRGBA.White);
}
public void plotPoints(Vector3f[] lineVerticies, ColorRGBA pointColor){
Mesh mesh = new Mesh();
mesh.setMode(Mesh.Mode.Points);
mesh.setBuffer(VertexBuffer.Type.Position, 3, BufferUtils.createFloatBuffer(lineVerticies));
mesh.updateBound();
mesh.updateCounts();
Geometry geo=new Geometry("line",mesh);
Material mat = new Material(assetManager, "Common/MatDefs/Misc/Unshaded.j3md");
mat.setColor("Color", pointColor);
geo.setMaterial(mat);
rootNode.attachChild(geo);
}
#Override
public void simpleUpdate(float tpf) {
//TODO: add update code
}
#Override
public void simpleRender(RenderManager rm) {
//TODO: add render code
}
}
This will create the points within pointVerticies as shown below
Later if you need to update infomation in a buffer you can do so using:
VertexBuffer posBuffer = mesh.getBuffer(Type.Position);
posBuffer.updateData(BufferUtils.createFloatBuffer(newData));
posBuffer.setUpdateNeeded();
mesh.updateCounts();
mesh.updateBound();
Or (much more efficiently) you can just attach your geometry to a node and move that (depending on your usage case).
Notes
In its most basic state the Vertex buffer expects x1,y1,z1,x2,y2,z2,x3.... etc with no demarcation between where one vertex ends and the other begins. So the following would enter 3 vertices into the buffer; (1.1,1.2,1.3), (2.1,2.2,2.3) and (3.1,3.2,3.3)
m.setBuffer(VertexBuffer.Type.Position, 3, new float[]{1.1,1.2,1.3,2.1,2.2,2.3,3.1,3.2,3.3});
However the createFloatBuffer() method converts from an array of Vector3f into this form.
Also; its often possible to 'get away with' not calling mesh.updateBound();, however without it objects may be culled because the graphics card believes them to be off screen when actually they are visible