Question

在将CategoryDataset的零值设置为非常大的数字后，我遇到了刷新/重新绘制BarChart的问题。

private class Test
    extends ApplicationFrame {

    private DefaultCategoryDataset set;

    public Test(
        String newTitle) {
        super(newTitle);
        set = new DefaultCategoryDataset();
        set.addValue(0, "Test", "1");
        JFreeChart barChart = ChartFactory.createBarChart(
                "Test",
                "Category",
                "Score",
                set,
                PlotOrientation.VERTICAL,
                true,
                true,
                false);

        JPanel mainPanel = new JPanel(new GridLayout());

        ChartPanel chartPanel = new ChartPanel(barChart);
        chartPanel.setPreferredSize(new java.awt.Dimension(560, 367));
        mainPanel.add(chartPanel);

        JButton b = new JButton();

        createDataset();
        b.addActionListener(e -> {
            set.setValue(Integer.MAX_VALUE, "Test", "1");
        });
        mainPanel.add(b);
        setContentPane(mainPanel);
        pack();
        setVisible(true);
    }

这是一个零值的图表。

将值设置为非常大的数字。

点击图表内部。

如何正确刷新图表？我试图重新绘制ChartPanel，但它没有用。

Answer 1

确保在event dispatch thread上构建和操作仅的Swing GUI对象。此外，覆盖getPreferredSize()，如图here所示，以确定图表的初始大小。在下面的变体中，请注意重复点击清除，零和更新按钮如何保持图表本身不变，同时更新数据集，绘图，范围轴和图例。

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import javax.swing.AbstractAction;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartPanel;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.data.category.DefaultCategoryDataset;

/**
 * @see https://stackoverflow.com/q/50854965/230513
 */
public class Test {

    private final DefaultCategoryDataset set = new DefaultCategoryDataset();
    private int i;

    private void display() {
        JFrame f = new JFrame("Test");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        set.addValue(0, "Test", "1");
        JFreeChart barChart = ChartFactory.createBarChart(
            "Test", "Category", "Score", set,
            PlotOrientation.VERTICAL, true, true, false);

        JPanel mainPanel = new JPanel(new BorderLayout());
        mainPanel.add(new ChartPanel(barChart) {
            @Override
            public Dimension getPreferredSize() {
                return new Dimension(567, 345);
            }
        });
        JPanel p = new JPanel();
        p.add(new JButton(new AbstractAction("Clear") {

            @Override
            public void actionPerformed(ActionEvent e) {
                set.clear();
                i = 0;
            }
        }));
        p.add(new JButton(new AbstractAction("Zero") {

            @Override
            public void actionPerformed(ActionEvent e) {
                set.setValue(0, "Test", "1");
                i = 0;
            }
        }));
        p.add(new JButton(new AbstractAction("Update") {

            @Override
            public void actionPerformed(ActionEvent e) {
                set.setValue(i += 10, "Test", "1");
            }
        }));
        mainPanel.add(p, BorderLayout.SOUTH);
        f.add(mainPanel);
        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }

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

JFreeChart CategoryDataset - 轴刷新/重绘问题

1 个答案: