Java Swing应用程序为什么不在屏幕上居中？

Question

我已经下载了Java Swing应用程序，尽管我在应用程序中有此行：demo.setLocationRelativeTo(null);

为什么它不在屏幕中央？

程序看起来像这样：

import java.awt.Color;
import java.awt.Dimension;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

import org.jfree.chart.*;
import org.jfree.chart.axis.NumberAxis;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.chart.plot.XYPlot;
import org.jfree.chart.renderer.xy.XYItemRenderer;
import org.jfree.data.xy.DefaultXYZDataset;
import org.jfree.data.xy.XYZDataset;

public class Bubble_Chart_AWT extends JFrame
{
  public Bubble_Chart_AWT(String s)
  {
    super(s);
    JPanel jpanel=createDemoPanel();
    jpanel.setPreferredSize(new Dimension(560,370));
    setContentPane(jpanel);
  }

  private JFreeChart createChart(XYZDataset xyzdataset)
  {
    JFreeChart jfreechart=ChartFactory.createBubbleChart("AGE vs WEIGHT vs WORK",
                                                         "Weight",
                                                         "AGE",
                                                         xyzdataset,
                                                         PlotOrientation.HORIZONTAL,
                                                         true,true,false);

    XYPlot xyplot=(XYPlot)jfreechart.getPlot();
    xyplot.setForegroundAlpha(0.65F);
    XYItemRenderer xyitemrenderer=xyplot.getRenderer();
    xyitemrenderer.setSeriesPaint(0,Color.blue);
    NumberAxis numberaxis=(NumberAxis)xyplot.getDomainAxis();
    numberaxis.setLowerMargin(0.2);
    numberaxis.setUpperMargin(0.5);
    NumberAxis numberaxis1=(NumberAxis)xyplot.getRangeAxis();
    numberaxis1.setLowerMargin(0.8);
    numberaxis1.setUpperMargin(0.9);

    return jfreechart;
  }

  public static XYZDataset createDataset()
  {
    DefaultXYZDataset defaultxyzdataset=new DefaultXYZDataset();
    double ad[]={30,40,50,60,70,80};
    double ad1[]={10,20,30,40,50,60};
    double ad2[]={4,5,10,8,9,6};
    double ad3[][]={ad,ad1,ad2};
    defaultxyzdataset.addSeries("Series 1",ad3);

    return defaultxyzdataset;
  }
  public JPanel createDemoPanel()
  {
    JFreeChart jfreechart=createChart(createDataset());
    ChartPanel chartpanel=new ChartPanel(jfreechart);

    chartpanel.setDomainZoomable(true);
    chartpanel.setRangeZoomable(true);

    return chartpanel;
  }

  public static void main(String args[])
  {
    SwingUtilities.invokeLater(() ->
    {
      Bubble_Chart_AWT demo=new Bubble_Chart_AWT("Bubble_Chart_AWT");
      demo.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      demo.setLocationRelativeTo(null);
      demo.pack();
      demo.setVisible(true);
    });
  }
}

您需要在http://repo1.maven.org/maven2/org/jfree/jfreechart/1.5.0/的项目“ lib”中运行此[jfreechart-1.5.0.jar]。

我应该怎么做，它会自动在屏幕上居中，通常“ demo.setLocationRelativeTo（null）”有效，但在此应用程序中不起作用。

Answer 1

您累了吗？>

Dimension dimension = Toolkit.getDefaultToolkit().getScreenSize();
int x = (int) ((dimension.getWidth() - demo.getWidth()) / 2);
int y = (int) ((dimension.getHeight() - demo.getHeight()) / 2);
demo.setLocation(x, y);

Answer 2

这可能会解决您的问题，它在我的系统上完成：