从Jcombobox选择项目后，如何更新图表？

Question

我正在尝试根据ComboBox列表中所选项目更改条形图的值。下面的代码是一个简短的示例。创建/更新图表的方法可与按钮Mouselistener或Action Perperformed ，但是当我从CompoBox列表中选择一个项目时，它不会立即更改。

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.Font;
 
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
 
import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartPanel;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.plot.CategoryPlot;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.chart.renderer.category.BarRenderer;
import org.jfree.chart.renderer.category.StandardBarPainter;
import org.jfree.data.category.DefaultCategoryDataset;
 
import javax.swing.JComboBox;
import javax.swing.DefaultComboBoxModel;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.JButton;
 
public class MainTest extends JFrame {
     
    private JPanel contentPane;
    private JPanel panel;
    private JComboBox<String> comboBox;
    private static JPanel chartMainPanel;
     
    static String selectedItem = "Select";
     
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    MainTest frame = new MainTest();
                    frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }
     
    public MainTest() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(100, 100, 474, 409);
        contentPane = new JPanel();
        contentPane.setBackground(Color.WHITE);
        contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
        setContentPane(contentPane);
        contentPane.setLayout(null);
         
        panel = new JPanel();
        panel.setBounds(0, 0, 458, 370);
        contentPane.add(panel);
        panel.setLayout(null);
         
        comboBox = new JComboBox<String>();
        comboBox.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                if (!comboBox.getSelectedItem().equals("Select")) {
                    selectedItem = comboBox.getSelectedItem().toString();
                }
                else {
                    selectedItem = "Select";
                }
                chart();
            }
        });
        comboBox.setFocusable(false);
        comboBox.setModel(new DefaultComboBoxModel<String>(new String[] {"Select", "First", "Second", "Third"}));
        comboBox.setBounds(10, 11, 146, 28);
        panel.add(comboBox);
         
        chartMainPanel = new JPanel();
        chartMainPanel.setBounds(10, 105, 438, 176);
        panel.add(chartMainPanel);
        chartMainPanel.setLayout(new BorderLayout(0, 0));
         
        JButton btnNewButton = new JButton("Refresh");
        btnNewButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                chart();
            }
        });
        btnNewButton.setBounds(166, 11, 103, 28);
        panel.add(btnNewButton);
         
        chart();
    }
    public static void chart() {
        DefaultCategoryDataset dataset = new DefaultCategoryDataset();
        int a1 = 0;
        int a2 = 0;
        int a3 = 0;
         
        int b1 = 0;
        int b2 = 0;
        int b3 = 0;
         
        int c1 = 0;
        int c2 = 0;
        int c3 = 0;
         
        if (selectedItem.equals("First")) {
            a1 = 1;
            a2 = 1;
            a3 = 1;
             
            b1 = 1;
            b2 = 1;
            b3 = 1;
             
            c1 = 1;
            c2 = 1;
            c3 = 1;
        }
        else if (selectedItem.equals("Second")) {
            a1 = 2;
            a2 = 2;
            a3 = 2;
             
            b1 = 2;
            b2 = 2;
            b3 = 2;
             
            c1 = 2;
            c2 = 2;
            c3 = 2;
        }
        else if (selectedItem.equals("Third")) {
            a1 = 3;
            a2 = 3;
            a3 = 3;
             
            b1 = 3;
            b2 = 3;
            b3 = 3;
             
            c1 = 3;
            c2 = 3;
            c3 = 3;
        }
        else {
            a1 = 0;
            a2 = 0;
            a3 = 0;
             
            b1 = 0;
            b2 = 0;
            b3 = 0;
             
            c1 = 0;
            c2 = 0;
            c3 = 0;
        }
         
        dataset.setValue(a1, "part 1", "Q1");
        dataset.setValue(a2, "part 1", "Q2");
        dataset.setValue(a3, "part 1", "Q3");
         
        dataset.setValue(b1, "part 2", "Q1");
        dataset.setValue(b2, "part 2", "Q2");
        dataset.setValue(b3, "part 2", "Q3");
         
        dataset.setValue(c1, "part 3", "Q1");
        dataset.setValue(c2, "part 3", "Q2");
        dataset.setValue(c3, "part 3", "Q3");
         
        Font font = new Font("Tahoma", Font.PLAIN, 12);
        Font font2 = new Font("Tahoma", Font.PLAIN, 13);
         
        JFreeChart chart = ChartFactory.createBarChart("", "", "Rating", dataset, PlotOrientation.VERTICAL, false, false, false);
        CategoryPlot categoryPlot = chart.getCategoryPlot();
        categoryPlot.setBackgroundPaint(Color.WHITE);
        categoryPlot.setRangeGridlinePaint(Color.GRAY);
        categoryPlot.setOutlinePaint(Color.WHITE);
         
        categoryPlot.getDomainAxis().setLabelFont(font);
        categoryPlot.getDomainAxis().setTickLabelFont(font);
        categoryPlot.getDomainAxis().setTickLabelPaint(new Color(160, 163, 165));
         
        categoryPlot.getRangeAxis().setLabelFont(font2);
        categoryPlot.getRangeAxis().setTickLabelFont(font2);
        categoryPlot.getRangeAxis().setTickLabelPaint(new Color(160, 163, 165));
        categoryPlot.getRangeAxis().setRange(0, 3);
         
        ((BarRenderer) categoryPlot.getRenderer()).setBarPainter(new StandardBarPainter());
        BarRenderer renderer = (BarRenderer)chart.getCategoryPlot().getRenderer();
        renderer.setMaximumBarWidth(0.04);
        renderer.setSeriesPaint(0, new Color(102, 204, 255));
        renderer.setSeriesPaint(1, new Color(102, 204, 153));
         
        ChartPanel chartPanel = new ChartPanel(chart);
        chartMainPanel.add(chartPanel, BorderLayout.CENTER);
        chartPanel.setPopupMenu(null);
        chartPanel.removeAll();
        chartPanel.setMouseZoomable(false, false);
        chartPanel.revalidate();    
    }
}

Answer 1

您无需替换 ChartPanel 每次您想查看新的categoryDataSet;只需设置绘图的新数据集，例如在这里。此示例具有jcombobox＆lt; string＆gt;用于选择的 map＆lt string，categoryDataSet＆gt;从中可以选择：

combo.addItemListener((ItemEvent e) -> {
    var key = (String) e.getItem();
    plot.setDataset(map.get(key));
});

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.event.ItemEvent;
import java.util.HashMap;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JPanel;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartPanel;
import org.jfree.chart.plot.CategoryPlot;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.data.category.CategoryDataset;
import org.jfree.data.category.DefaultCategoryDataset;

public class ComboTest {

    private DefaultCategoryDataset createDataset(int i) {
        var set = new DefaultCategoryDataset();
        for (int j = 1; j < 4; j++) {
            set.addValue(i * 1, "Series 1", "Category " + j);
            set.addValue(i * 2, "Series 2", "Category " + j);
            set.addValue(i * 3, "Series 3", "Category " + j);
        }
        return set;
    }

    private void display() {
        var keys = new String[]{"Zero", "One", "Two", "Three", "Four"};
        var barChart = ChartFactory.createBarChart("", "Category", "Score",
            null, PlotOrientation.VERTICAL, true, true, false);
        var plot = (CategoryPlot) barChart.getPlot();
        var map = new HashMap<String, CategoryDataset>();
        var combo = new JComboBox<String>();
        for (int i = 0; i < keys.length; i++) {
            map.put(keys[i], createDataset(i));
            combo.addItem(keys[i]);
        }
        combo.addItemListener((ItemEvent e) -> {
            var key = (String) e.getItem();
            plot.setDataset(map.get(key));
        });
        combo.setSelectedIndex(keys.length / 2);
        var controlPanel = new JPanel();
        controlPanel.add(combo);
        var f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(controlPanel, BorderLayout.NORTH);
        f.add(new ChartPanel(barChart) {
            @Override
            public Dimension getPreferredSize() {
                return new Dimension(567, 345);
            }
        });
        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }

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