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java - 已添加JPanel，但未“及时”显示

我有一个JFrame根据您单击的MenuItem显示JPanels。它可以工作，但是现在我需要在将JPanel添加到框架中并显示该方法之后调用一个方法(因为我在该面板内使用JFreeChart，并且当JPanel可见时我必须调用chartPanel.repaint()):

this.getContentPane().add( myjpanel, BorderLayout.CENTER ); //this = JFrame
this.validate();
myjpanel.methodCalledOnceDisplayed();

看起来还好吗？确实显示了myjpanel吗？似乎不是:
public void methodCalledOnceDisplayed() {
    chartPanel.repaint()
}

这是行不通的(chartPanel.getChartRenderingInfo().getPlotInfo().getSubplotInfo(0)抛出IndexOutOfBoundsException)。这意味着在调用repaint时，JPanel不可见，我已经测试了以下内容:
public void methodCalledOnceDisplayed() {
    JOptionPane.showMessageDialog(null,"You should see myjpanel now");
    chartPanel.repaint()
}

现在它可以正常工作了，我在警报后面看到了myjpanel，正如预期的那样，chartPanel重新绘制，并且没有发生异常。

编辑:SSCCE(需要jfreechart和jcommon:http://www.jfree.org/jfreechart/download.html)

导入java.awt.BorderLayout;
导入java.awt.EventQueue;
导入java.awt.Font;
导入javax.swing.JButton;
导入javax.swing.JFrame;
导入javax.swing.JLabel;
导入javax.swing.JOptionPane;
导入javax.swing.JPanel;
导入javax.swing.border.EmptyBorder;
导入org.jfree.chart.ChartMouseEvent;
导入org.jfree.chart.ChartMouseListener;
导入org.jfree.chart.JFreeChart;
导入org.jfree.chart.plot.CombinedDomainXYPlot;
导入org.jfree.chart.plot.PlotOrientation;
导入org.jfree.chart.plot.XYPlot;
导入org.jfree.chart.ChartPanel;
导入org.jfree.data.time.TimeSeries;
导入org.jfree.data.time.TimeSeriesCollection;
导入org.jfree.data.xy.XYDataset;
导入java.awt.event.ActionListener;
导入java.awt.event.ActionEvent;

公共类Window扩展JFrame {
私人JPanel contentPane;

公共静态void main(String [] args){
EventQueue.invokeLater(new Runnable(){
公共无效run(){
尝试{
窗框= new Window();
frame.setVisible(true);
} catch(Exception e){
e.printStackTrace();
}
}
});
}

公共窗口(){
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setBounds(100，100，700，500);
contentPane =新的JPanel();
contentPane.setBorder(newEmptyBorder(5，5，5，5));
contentPane.setLayout(new BorderLayout(0，0));
setContentPane(contentPane);

JButton clickme = new JButton(“Click me”);
clickme.addActionListener(new ActionListener(){
公共无效actionPerformed(ActionEvent arg0){
contentPane.removeAll();
MyJPanel mypanel = new MyJPanel();
contentPane.add(mypanel，BorderLayout.CENTER);
validate();
mypanel.methodCalledOnceDisplayed();
}
});
contentPane.add(clickme，BorderLayout.NORTH);
JPanel示例= new JPanel();
example.add(new JLabel(“Example JPanel”));
contentPane.add(例如BorderLayout.CENTER);
}

}

类MyJPanel扩展JPanel实现ChartMouseListener {
私人ChartPanel chartPanel;
私人JFreeChart图表；
私有XYPlot subplotTop;
私有XYPlot subplotBottom;
私人的CombinedDomainXYPlot图;

公共MyJPanel(){
this.add(new JLabel(“此JPanel包含图表”));
createCombinedChart();
chartPanel =新的ChartPanel(图表);
chartPanel.addChartMouseListener(this);
this.add(chartPanel);
}

私人无效createCombinedChart(){
图=新的CombinedDomainXYPlot();
plot.setGap(30);
createSubplots();
plot.add(subplotTop，4);
plot.add(subplotBottom，1);
plot.setOrientation(PlotOrientation.VERTICAL);

chart = new JFreeChart(“Title”，new Font(“Arial”，Font.BOLD，20)，plot，true)；
}

私人无效createSubplots(){
subplotTop =新的XYPlot();
subplotBottom =新的XYPlot();

subplotTop.setDataset(emptyDataset(“Empty 1”));
subplotBottom.setDataset(emptyDataset(“Empty 2”));;
}

私人XYDataset emptyDataset(字符串标题){
TimeSeries ts = new TimeSeries(title);
TimeSeriesCollection tsc =新的TimeSeriesCollection();
tsc.addSeries(ts);
返回tsc;
}

@Override
public void chartMouseMoved(ChartMouseEvent e){
System.out.println(“鼠标移动!”);
}
@Override
公共无效chartMouseClicked(ChartMouseEvent arg0){}

公共无效methodCalledOnceDisplayed(){
JOptionPane.showMessageDialog(null，“Magic!”); //尝试注释此行并查看控制台
chartPanel.repaint();
//现在我们可以获取图表区域
this.chartPanel.getChartRenderingInfo()。getPlotInfo()。getSubplotInfo(0).getDataArea();
this.chartPanel.getChartRenderingInfo()。getPlotInfo()。getSubplotInfo(1).getDataArea();
}
}

查看使用和不使用JOptionPane时发生的情况。

最佳答案

为什么会发生这种情况的解释会很好。

您可以从以下变体中获得一些见解。注意

  • Swing GUI对象应该仅在event dispatch thread(EDT)上构造和操作，原因是建议使用here。
  • 即使用户交互仅限于模式对话框，EDT仍将继续处理事件，如示例中所示。
  • 使用repaint()时不需要调用ChartPanel。
  • 比手动容器操作更喜欢 CardLayout 或 JTabbedPane 。
  • 而不是调用setPreferredSize()，而是覆盖getPreferredSize()，如here所述。

    • 附录:您删除了显示问题的两行……。
    ChartRenderingInfo是动态数据，在呈现图表之前不存在。模式图对话框在后台更新图表时处理事件。没有它，您可以通过将方法包装在适合Runnable的invokeLater()中来安排方法:
    EventQueue.invokeLater(new Runnable() {

    @Override
    public void run() {
        myPanel.methodCalledOnceDisplayed();
    }
});

    更好的方案是在您知道数据有效的侦听器中访问ChartRenderingInfo，即由ChartPanel实现的侦听器。
    import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Date;
import java.util.Random;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.Timer;
import javax.swing.border.EmptyBorder;
import org.jfree.chart.ChartPanel;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.axis.DateAxis;
import org.jfree.chart.axis.NumberAxis;
import org.jfree.chart.plot.CombinedDomainXYPlot;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.chart.plot.PlotRenderingInfo;
import org.jfree.chart.plot.XYPlot;
import org.jfree.chart.renderer.xy.XYLineAndShapeRenderer;
import org.jfree.data.time.Day;
import org.jfree.data.time.TimeSeries;
import org.jfree.data.time.TimeSeriesCollection;
import org.jfree.data.xy.XYDataset;

/**
* @see https://stackoverflow.com/a/14894894/230513
*/
public class Test extends JFrame {

    private JPanel panel;

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {
                Test frame = new Test();
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public Test() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        final MyJPanel myPanel = new MyJPanel();
        panel = new JPanel() {

            @Override
            public Dimension getPreferredSize() {
                return myPanel.getPreferredSize();
            }
        };
        panel.setBorder(new EmptyBorder(5, 5, 5, 5));
        panel.setLayout(new BorderLayout());
        add(panel);

        myPanel.start();
        JButton clickme = new JButton("Click me");
        clickme.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent arg0) {
                panel.removeAll();
                panel.add(myPanel, BorderLayout.CENTER);
                validate();
                EventQueue.invokeLater(new Runnable() {

                    @Override
                    public void run() {
                        myPanel.methodCalledOnceDisplayed();
                    }
                });
            }
        });
        panel.add(clickme, BorderLayout.NORTH);
        JPanel example = new JPanel();
        example.add(new JLabel("Example JPanel"));
        panel.add(example, BorderLayout.CENTER);
    }

    private static class MyJPanel extends JPanel {

        private static final Random r = new Random();
        private ChartPanel chartPanel;
        private JFreeChart chart;
        private XYPlot subplotTop;
        private XYPlot subplotBottom;
        private CombinedDomainXYPlot plot;
        private Timer timer;
        private Day now = new Day(new Date());

        public MyJPanel() {
            this.add(new JLabel("Chart panel"));
            createCombinedChart();
            chartPanel = new ChartPanel(chart);
            this.add(chartPanel);
            timer = new Timer(1000, new ActionListener() {

                @Override
                public void actionPerformed(ActionEvent e) {
                    update(subplotTop);
                    update(subplotBottom);
                }
            });
            timer.start();
        }

        public void start() {
            timer.start();
        }

        private void update(XYPlot plot) {
            TimeSeriesCollection t = (TimeSeriesCollection) plot.getDataset();
            for (int i = 0; i < t.getSeriesCount(); i++) {
                TimeSeries s = t.getSeries(i);
                s.add(now, Math.abs(r.nextGaussian()));
                now = (Day) now.next();
            }
        }

        private void createCombinedChart() {
            plot = new CombinedDomainXYPlot();
            plot.setGap(30);
            createSubplots();
            plot.add(subplotTop, 4);
            plot.add(subplotBottom, 1);
            plot.setOrientation(PlotOrientation.VERTICAL);
            chart = new JFreeChart("Title",
                JFreeChart.DEFAULT_TITLE_FONT, plot, true);
            plot.setDomainAxis(new DateAxis("Domain"));
        }

        private void createSubplots() {
            subplotTop = new XYPlot();
            subplotBottom = new XYPlot();
            subplotTop.setDataset(emptyDataset("Set 1"));
            subplotTop.setRenderer(new XYLineAndShapeRenderer());
            subplotTop.setRangeAxis(new NumberAxis("Range"));
            subplotBottom.setDataset(emptyDataset("Set 2"));
            subplotBottom.setRenderer(new XYLineAndShapeRenderer());
            subplotBottom.setRangeAxis(new NumberAxis("Range"));
        }

        private XYDataset emptyDataset(String title) {
            TimeSeriesCollection tsc = new TimeSeriesCollection();
            TimeSeries ts = new TimeSeries(title);
            tsc.addSeries(ts);
            return tsc;
        }

        public void methodCalledOnceDisplayed() {
            PlotRenderingInfo plotInfo =
                this.chartPanel.getChartRenderingInfo().getPlotInfo();
            for (int i = 0; i < plotInfo.getSubplotCount(); i++) {
                System.out.println(plotInfo.getSubplotInfo(i).getDataArea());
            }
            JOptionPane.showMessageDialog(null, "Magic!");
        }
    }
}

    附录:进行一次额外的迭代来说明ChartMouseListener并清除一些松散的结局。
    import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Date;
import java.util.Random;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
import org.jfree.chart.ChartMouseEvent;
import org.jfree.chart.ChartMouseListener;
import org.jfree.chart.ChartPanel;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.axis.DateAxis;
import org.jfree.chart.axis.NumberAxis;
import org.jfree.chart.entity.ChartEntity;
import org.jfree.chart.plot.CombinedDomainXYPlot;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.chart.plot.XYPlot;
import org.jfree.chart.renderer.xy.XYLineAndShapeRenderer;
import org.jfree.data.time.Day;
import org.jfree.data.time.TimeSeries;
import org.jfree.data.time.TimeSeriesCollection;
import org.jfree.data.xy.XYDataset;

/**
 * @see https://stackoverflow.com/a/14894894/230513
 */
public class Test {

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {
                Test t = new Test();
            }
        });
    }

    public Test() {
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        final MyJPanel myPanel = new MyJPanel();
        f.add(myPanel, BorderLayout.CENTER);
        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);
        myPanel.start();
    }

    private static class MyJPanel extends JPanel {

        private static final Random r = new Random();
        private ChartPanel chartPanel;
        private JFreeChart chart;
        private XYPlot subplotTop;
        private XYPlot subplotBottom;
        private CombinedDomainXYPlot plot;
        private Timer timer;
        private Day now = new Day(new Date());

        public MyJPanel() {
            createCombinedChart();
            chartPanel = new ChartPanel(chart);
            this.add(chartPanel);
            timer = new Timer(1000, new ActionListener() {

                @Override
                public void actionPerformed(ActionEvent e) {
                    update(subplotTop);
                    update(subplotBottom);
                    now = (Day) now.next();
                }
            });
            chartPanel.addChartMouseListener(new ChartMouseListener() {

                @Override
                public void chartMouseClicked(ChartMouseEvent e) {
                    final ChartEntity entity = e.getEntity();
                    System.out.println(entity + " " + entity.getArea());
                }

                @Override
                public void chartMouseMoved(ChartMouseEvent e) {
                }
            });
        }

        public void start() {
            timer.start();
        }

        private void update(XYPlot plot) {
            TimeSeriesCollection t = (TimeSeriesCollection) plot.getDataset();
            for (int i = 0; i < t.getSeriesCount(); i++) {
                TimeSeries s = t.getSeries(i);
                s.add(now, Math.abs(r.nextGaussian()));
            }
        }

        private void createCombinedChart() {
            plot = new CombinedDomainXYPlot();
            createSubplots();
            plot.add(subplotTop, 4);
            plot.add(subplotBottom, 1);
            plot.setOrientation(PlotOrientation.VERTICAL);
            chart = new JFreeChart("Title",
                JFreeChart.DEFAULT_TITLE_FONT, plot, true);
            plot.setDomainAxis(new DateAxis("Domain"));
        }

        private void createSubplots() {
            subplotTop = new XYPlot();
            subplotBottom = new XYPlot();
            subplotTop.setDataset(emptyDataset("Set 1"));
            subplotTop.setRenderer(new XYLineAndShapeRenderer());
            subplotTop.setRangeAxis(new NumberAxis("Range"));
            subplotBottom.setDataset(emptyDataset("Set 2"));
            subplotBottom.setRenderer(new XYLineAndShapeRenderer());
            subplotBottom.setRangeAxis(new NumberAxis("Range"));
        }

        private XYDataset emptyDataset(String title) {
            TimeSeriesCollection tsc = new TimeSeriesCollection();
            TimeSeries ts = new TimeSeries(title);
            tsc.addSeries(ts);
            return tsc;
        }
    }
}

    10-08 01:58
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