我有一个javafx应用程序，该应用程序在屏幕上对机器人（黑点）进行动画，并在他们去过任何地方的Lighgray背景上绘制了一条小小的白色线（想想Tron）。为此，我保留了机器人和所有白色像素的所有坐标。机器人的行为由其他可运行的线程控制，并且在模拟运行时可以更改。机器人坐标存储在一个哈希图中，坐标为bee bee bee bee bee tops延长点并使用双倍的x和y值进行更高的内部计算精度。对于白点，我正在使用hashmap，因为整数精度对它们来说足够了，因为它们不移动并留在屏幕上的X和y坐标上。
现在，该程序运行良好，但是当hashmap存储白点的要点时，越来越有可能崩溃应用程序的Javafx线程（开始考虑一下，更具体地说，它是机器人所在的帆布绘制。但是什么都没有动画，几秒钟后，画布变白了。增加螺纹的MS.sleep（MS）使该程序更加稳定，但疼痛的速度非常慢。同样，它在我的学校慢上书本（跑步XP）上比在我的家庭桌面PC（运行Win7 64bit）上更频繁地发生。例外也是一个例外。对于桌面PC，如下：
java.lang.InternalError: Unrecognized PGCanvas token: 68
at com.sun.javafx.sg.prism.NGCanvas.renderStream(NGCanvas.java:651)
at com.sun.javafx.sg.prism.NGCanvas.renderContent(NGCanvas.java:320)
at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:187)
at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:39)
at com.sun.javafx.sg.BaseNode.render(BaseNode.java:1145)
at com.sun.javafx.sg.prism.NGGroup.renderContent(NGGroup.java:204)
at com.sun.javafx.sg.prism.NGRegion.renderContent(NGRegion.java:420)
at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:187)
at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:39)
at com.sun.javafx.sg.BaseNode.render(BaseNode.java:1145)
at com.sun.javafx.tk.quantum.ViewPainter.doPaint(ViewPainter.java:117)
at com.sun.javafx.tk.quantum.AbstractPainter.paintImpl(AbstractPainter.java:175)
at com.sun.javafx.tk.quantum.PresentingPainter.run(PresentingPainter.java:73)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
at java.util.concurrent.FutureTask$Sync.innerRunAndReset(FutureTask.java:351)
at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:178)
at com.sun.prism.render.RenderJob.run(RenderJob.java:37)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at com.sun.javafx.tk.quantum.QuantumRenderer$PipelineRunnable.run(QuantumRenderer.java:98)
at java.lang.Thread.run(Thread.java:724)
上网本是：
java.lang.IllegalArgumentException: alpha value out of range
at java.awt.AlphaComposite.<init>(AlphaComposite.java:624)
at java.awt.AlphaComposite.getInstance(AlphaComposite.java:689)
at java.awt.AlphaComposite.derive(AlphaComposite.java:761)
at com.sun.prism.j2d.J2DPrismGraphics.setExtraAlpha(J2DPrismGraphics.java:569)
at com.sun.javafx.sg.prism.NGCanvas.renderStream(NGCanvas.java:739)
at com.sun.javafx.sg.prism.NGCanvas.renderContent(NGCanvas.java:389)
at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:201)
at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:40)
at com.sun.javafx.sg.BaseNode.render(BaseNode.java:1145)
at com.sun.javafx.sg.prism.NGGroup.renderContent(NGGroup.java:204)
at com.sun.javafx.sg.prism.NGRegion.renderContent(NGRegion.java:420)
at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:201)
at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:40)
at com.sun.javafx.sg.BaseNode.render(BaseNode.java:1145)
at com.sun.javafx.tk.quantum.ViewPainter.doPaint(ViewPainter.java:117)
at com.sun.javafx.tk.quantum.AbstractPainter.paintImpl(AbstractPainter.java:182)
at com.sun.javafx.tk.quantum.PresentingPainter.run(PresentingPainter.java:73)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
at java.util.concurrent.FutureTask$Sync.innerRunAndReset(FutureTask.java:351)
at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:178)
at com.sun.prism.render.RenderJob.run(RenderJob.java:37)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
at com.sun.javafx.tk.quantum.QuantumRenderer$PipelineRunnable.run(QuantumRenderer.java:108)
at java.lang.Thread.run(Thread.java:722)
任何帮助解决或缩小此问题的帮助将不胜感激。
编辑：正如建议的那样，我将添加一个最小的代码示例，这些示例仍然显示出该问题。主要方法在于绘制模拟区域的类可视化器
import java.awt.Point;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import javafx.application.Application;
import javafx.geometry.Rectangle2D;
import javafx.scene.Scene;
import javafx.scene.canvas.Canvas;
import javafx.scene.canvas.GraphicsContext;
import javafx.scene.layout.BorderPane;
import javafx.scene.paint.Color;
import javafx.stage.Screen;
import javafx.stage.Stage;
public class Visualizer extends Application {
private static GraphicsContext gc;
private static Canvas canvas;
private static BorderPane pane;
private static Scene scene;
private static Thread thread;
private static Simulator sim = new Simulator();
private static int optionsWidth = 200;
private static HashSet<Point> manganCollected = new HashSet<Point>();
private static HashMap<Integer, Coordinates> coordinates = new HashMap<Integer, Coordinates>();
private static final int zoom = 4;
private static Point cmpP;
/**
* Height in pixels that's available to draw the simulation on dependent on used monitor resolution
*/
public static double simHeight;
/**
* Width in pixels that's available to draw the simulation on dependent on used monitor resolution
*/
public static double simWidth;
/**
* Launches the JavaFX application
* @param args command line arguments if there are any
*/
public static void main(String[] args) {
launch(args);
}
/**
* Sets up the GUI with all options and the canvas to draw the robots on
*/
@Override
public void start(Stage stage) throws Exception {
// Determine screen width of the monitor
Screen screen = Screen.getPrimary();
Rectangle2D bounds = screen.getVisualBounds();
double screenHeight = bounds.getHeight();
double screenWidth = bounds.getWidth();
// set the stage
stage.setFullScreen(true);
stage.setHeight(screenHeight);
stage.setWidth(screenWidth);
stage.setTitle("Manganernte");
// Canvas to draw the simulation on
canvas = new Canvas();
simHeight = screenHeight;
simWidth = screenWidth - optionsWidth;
canvas.setHeight(simHeight);
canvas.setWidth(simWidth);
gc = canvas.getGraphicsContext2D();
gc = canvas.getGraphicsContext2D();
gc.setFill(Color.LIGHTGRAY);
gc.fillRect(0, 0, simWidth, simHeight);
gc.setStroke(Color.BLACK);
gc.setLineWidth(3);
gc.strokeRect(0, 0, simWidth, simHeight);
// BorderPane containing the buttons box and the Simulator canvas
pane = new BorderPane();
pane.setCenter(canvas);
// Scene containing the pane
scene = new Scene(pane);
// Show the whole stage
stage.setScene(scene);
stage.show();
thread = new Thread(sim);
thread.start();
}
/**
* Transforms double coordinates as used by the simulator (0/0 in the center) to monitor coordinates (0/0 top left corner)
* @param coordinates Floating point coordinates that should be transformed
* @return Coordinates Floating point coordinates that have been transformed
*/
private static Coordinates transform(Coordinates coordinates) {
return new Coordinates(Math.round((simWidth / 2) + (zoom * coordinates.getX())), Math.round((simHeight / 2) + (zoom * coordinates.getY())));
}
/**
* Transforms integer coordinates as used by the simulator (0/0 in the center) to monitor coordinates (0/0 top left corner)
* @param Point Integer coordinates that should be transformed
* @return Point Integer coordinates that have been transformed
*/
private static Point transform(Point point) {
return new Point((int)Math.round((simWidth / 2) + (zoom * point.getX())), (int)Math.round(((simHeight / 2) + (zoom * point.getY()))));
}
/**
* Clear the canvas by drawing a rectangle filled with light gray background
*/
private static void clear () {
gc.setFill(Color.LIGHTGRAY);
gc.fillRect(0, 0, simWidth, simHeight);
gc.setStroke(Color.BLACK);
gc.setLineWidth(3);
gc.strokeRect(0, 0, simWidth, simHeight);
}
/**
* Clears the canvas and then draws first the collected mangan as white rectangles followed by robots as black circles the given coordinates
* @param redraw boolean that's set to true if iteration hasn't changed but a redraw should be forced anyway (e.g. when simulation is paused and the zoom is used)
*/
public static void DrawRobots() {
coordinates = Simulator.coordinates;
manganCollected = Simulator.manganCollected;
// clear the canvas with light gray background
clear();
// draw harvested mangan as white dots
gc.setFill(Color.WHITE);
Iterator<Point> it = manganCollected.iterator();
while(it.hasNext()) {
cmpP = it.next().getLocation();
double x = transform(cmpP).getX();
double y = transform(cmpP).getY();
gc.fillRect(x, y, zoom, zoom);
}
// draw robots
gc.setFill(Color.BLACK);
for(int i = 1; i <= coordinates.size(); i++) {
double x = transform(coordinates.get(i)).getX();
double y = transform(coordinates.get(i)).getY();
gc.fillOval(x, y, zoom, zoom);
}
}
}
模拟器类：
import java.awt.Point;
import java.util.HashMap;
import java.util.HashSet;
public class Simulator implements Runnable {
// start variable declarations
// HashMap of all robot objects the simulator controls
private static HashMap<Integer, Robot> robots = new HashMap<Integer, Robot>();
// HashMap of all coordinate objects the simulator controls
public static HashMap<Integer, Coordinates> coordinates = new HashMap<Integer, Coordinates>();
// HashMap of all point objects containing the coordinates of places where the mangan has already been collected
public static HashSet<Point> manganCollected = new HashSet<Point>();
/**
* communication radius of the robots according to the requirements
*/
public static int processSpeed = 100;
// end variable declarations
/**
* Create a robot with x and y
* @param x x-coordinate
* @param y y-coordinate
*/
public static void createRobot(int x, int y) {
coordinates.put(coordinates.size() + 1, new Coordinates(x, y));
robots.put(robots.size() + 1, new Robot());
}
/**
* Checks the status, changes it if necessary and acts accordingly
*/
@Override
public void run() {
for(int i = 0; i < 100; i++) createRobot(i - 50, 0);
Visualizer.DrawRobots();
while(true) {
for(int i = 1; i <= robots.size(); i++) robots.get(i).think();
for(int i = 1; i <= robots.size(); i++) {
coordinates.get(i).add(robots.get(i).move());
manganCollected.add(new Point((int)Math.round(coordinates.get(i).getX()), (int)Math.round(coordinates.get(i).getY())));
}
Visualizer.DrawRobots();
try {
Thread.sleep(processSpeed);
} catch(InterruptedException e) {
e.printStackTrace();
}
}
}
}
最后，在这个最小示例中，机器人类别不再有太大的作用：
public class Robot {
Coordinates future = new Coordinates(0, 0);
public void think () {
future.setY(1.0);
}
public Coordinates move() {
return future;
}
}
更新刚刚安装了JDK 8，现在的例外更具说服力：
Exception in thread "Thread-4" java.lang.IllegalStateException: Not on FX application thread; currentThread = Thread-4
搜索网络，似乎我需要使用platform.runlater（）避免这种情况。但是我不确定该怎么做。我将尝试再次解释我的项目现在如何结构：
我有class 可视化器扩展了 application ，其中还包括main（）方法，并在GraphicsContext Canvas上绘制了UI（包括仿真区域）作为灰色矩形。完成UI后，它会创建一个实现 Runnable 的类 simulator 的线程。 simulator 类中的run（）方法它输入了一段时间（true）循环。只要没有单击按钮，循环除了线程（）外什么都没有。如果单击"开始"按钮，则执行一些计算，并在可视化器上使用某些方法将其绘制在仿真画布上的东西。我的理解是，这些呼叫会导致例外，因为它们是由非Javafx线程制成的。
我是否必须使用Runlater（）来避免此问题，如果是这样，我该怎么办？
更新2 终于通过将所有关于UI/Canvas的公共方法包装到Runlater Block中，例如。
。public static void drawStuff() {
Platform.runLater(new Runnable() {
@Override
public void run() {
// draw stuff
}
});
}
只是发布此信息，因此读者很明显问题实际上具有答案/解决方案。
我遇到了同样的问题，正如作者最终指出的那样，以"更新"。
如果您有这个问题，则可能是在另一个线程中进行UI帆布操作。您应该在应用程序线程上始终进行UI操作！使用
Platform.runLater(()->{
//your code
});