任何人都可以帮助我提供以下错误报告（对于底部的代码）：
Exception in thread "AWT-EventQueue-0" java.lang.VerifyError: Constructor must call super() or this() before return in method org.jfree.ui.RectangleInsets.<init>()V at offset 0
at org.jfree.chart.axis.Axis.<clinit>(Axis.java:153)
at org.jfree.chart.StandardChartTheme.<init>(StandardChartTheme.java:233)
at org.jfree.chart.StandardChartTheme.<init>(StandardChartTheme.java:319)
at org.jfree.chart.ChartFactory.<clinit>(ChartFactory.java:231)
at odesolver.ODESolver.createGraph(ODESolver.java:81)
at odesolver.ODESolver.<init>(ODESolver.java:35)
at odesolver.ODESolver$2.run(ODESolver.java:105)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:251)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:733)
at java.awt.EventQueue.access$200(EventQueue.java:103)
at java.awt.EventQueue$3.run(EventQueue.java:694)
at java.awt.EventQueue$3.run(EventQueue.java:692)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:703)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)
BUILD SUCCESSFUL (total time: 2 seconds)
这与以下 3 行代码有关：
ODESolver.java:81
JFreeChart chart = ChartFactory.createXYLineChart(
ODESolver.java:35
createGraph();
ODESolver.java:105
new ODESolver(); // Let the constructor do the job
整个程序：
/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package odesolver;
/**
*
* @author User
*/
import java.awt.*; // Using AWT containers and components
import java.awt.event.*; // Using AWT events and listener interfaces
import javax.swing.*; // Using Swing components and containers
import org.jfree.data.xy.XYSeries;
import org.jfree.data.xy.XYSeriesCollection;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.chart.ChartPanel;
import org.jfree.data.general.Series;
// A Swing GUI application inherits the top-level container javax.swing.JFrame
public class ODESolver extends JFrame {
private JTextField tfInput, tfOutput;
private int numberIn; // input number
private int sum = 0; // accumulated sum, init to 0
/** Constructor to setup the GUI */
public ODESolver() {
// Retrieve the content-pane of the top-level container JFrame
// All operations done on the content-pane
Container cp = getContentPane();
cp.setLayout(new GridLayout(2, 2, 5, 5));
createGraph();
add(new JLabel("Enter an Integer: "));
tfInput = new JTextField(10);
add(tfInput);
add(new JLabel("The Accumulated Sum is: "));
tfOutput = new JTextField(10);
tfOutput.setEditable(false); // read-only
add(tfOutput);
// Allocate an anonymous instance of an anonymous inner class that
// implements ActionListener as ActionEvent listener
tfInput.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
// Get the String entered into the input TextField, convert to int
numberIn = Integer.parseInt(tfInput.getText());
sum += numberIn; // accumulate numbers entered into sum
tfInput.setText(""); // clear input TextField
tfOutput.setText(sum + ""); // display sum on the output TextField
}
});
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); // Exit program if close-window button clicked
setTitle("ODE Accumulator"); // "this" Frame sets title
setSize(350, 120); // "this" Frame sets initial size
setVisible(true); // "this" Frame shows
}
private JPanel createGraph() {
JPanel panel = new JPanel();
XYSeries series = new XYSeries("MyGraph");
series.add(0, 1);
series.add(1, 2);
series.add(2, 5);
series.add(7, 8);
series.add(9, 10);
XYSeriesCollection dataset = new XYSeriesCollection();
dataset.addSeries(series);
JFreeChart chart = ChartFactory.createXYLineChart(
"XY Chart",
"x-axis",
"y-axis",
dataset,
PlotOrientation.VERTICAL,
true,
true,
false
);
ChartPanel chartPanel = new ChartPanel(chart);
panel.add(chartPanel);
return panel;
}
/** The entry main() method */
public static void main(String[] args) {
// Run the GUI construction in the Event-Dispatching thread for thread-safety
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
new ODESolver(); // Let the constructor do the job
}
});
}
}
可能问题在于 ODESolver、src 和 lib 中的文件有错误，正如 netbeans 报告的那样（见下面的屏幕截图）。我不知道哪些文件应该有错误，因为没有一个文件上有感叹号，因为它们通常有错误。
