如何持续更新 JPanel？

Question

我遇到了一个小问题，我正在编写一个 gps 跟踪应用程序来同时跟踪多个对象。数据通过串行接口传入，据我所知，这很好。问题是我需要不断更新创建和显示地图的 JPanel。

public JPanel mapDisplay(){
    JPanel mapPanel = new JPanel();
    mapPanel.setSize(560, 540);
    Coordinate start = new Coordinate (-34.9286, 138.6);
    trackMap.addMapMarker(new MapMarkerDot(1Lat, 1Lon));
    trackMap.setDisplayPosition(start,8);
    System.out.println(1Lat);

    mapPanel.add(trackMap);
    mapPanel.setVisible(true);
    return mapPanel;
}

这就是我所拥有的，很高兴显示一次但不会更新。如果我在串行方法中打印出 1Lat 变量，它会不断打印，但它只在这里打印一次。

我找到的很多答案都涉及通过数组设置标记，但是在这种情况下这不起作用，因为我正在跟踪的对象可能在任何地方。

任何帮助将不胜感激:)

Answer 1

Is it possible to use a worker thread and not use an ArrayList? I would run the risk of missing data if I do.

不一定。在 SwingWorker 中，您对 doInBackground() 方法的实施可以 publish() 结果可用。请特别注意 "Results from multiple invocations of publish() are often accumulated for a single invocation of process()." 在您的 process() 中，只需循环遍历 List<Coordinate>，更新 route 和 repaint() map.

import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.event.MouseEvent;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JFrame;
import javax.swing.SwingWorker;
import org.openstreetmap.gui.jmapviewer.Coordinate;
import org.openstreetmap.gui.jmapviewer.JMapViewer;
import org.openstreetmap.gui.jmapviewer.MapPolygonImpl;

/**
 * @see 
 */
public class MapWorkerTest {

    private final List<Coordinate> route = new ArrayList<>();

    private void display() {
        JFrame f = new JFrame("MapWorker");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JMapViewer map = new JMapViewer() {

            @Override
            public Dimension getPreferredSize() {
                return new Dimension(640, 480);
            }

            @Override
            public String getToolTipText(MouseEvent e) {
                Coordinate c = (Coordinate) getPosition(e.getX(), e.getY());
                return c.getLat() + " " + c.getLon();
            }
        };
        map.setToolTipText("");
        Coordinate start = new Coordinate(-34.9286, 138.6);
        route.add(start);
        MapPolygonImpl poly = new MapPolygonImpl(route);
        poly.setColor(Color.blue);
        map.addMapPolygon(poly);
        map.setDisplayPosition(start, 10);
        f.add(map);
        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);
        new MapWorker(map, start).execute();
    }

    private class MapWorker extends SwingWorker<Void, Coordinate> {

        private final JMapViewer map;
        private Coordinate last;

        public MapWorker(JMapViewer map, Coordinate start) {
            this.map = map;
            this.last = start;
        }

        @Override
        protected Void doInBackground() throws Exception {
            while (!isCancelled()) {
                last = new Coordinate(last.getLat() + 0.0025, last.getLon() + 0.01);
                publish(last);
                Thread.sleep(1000);
            }
            return null;
        }

        @Override
        protected void process(List<Coordinate> chunks) {
            for (Coordinate c : chunks) {
                route.add(c);
            }
            map.repaint();
        }
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(new MapWorkerTest()::display);
    }
}

多条路线管理留作练习。

如何持续更新 JPanel？

How can I update JPanel continuously?

java

jpanel

jmapviewer