Can anyone help me with the following error report (for the code at the bottom):
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)
which relates to the following 3 lines of the code:
ODESolver.java:81
JFreeChart chart = ChartFactory.createXYLineChart(
ODESolver.java:35
createGraph();
ODESolver.java:105
new ODESolver(); // Let the constructor do the job
Whole program:
/*
* 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
}
});
}
}
Maybe the problem is that there are files in ODESolver, src and lib with errors, as netbeans reports (see screenshot below). I don't know which files are upposed to have errors though, as none of then have an exclamation mark on them, as they usually do of they have errors.
You appear to be running an old version of JFreeChart
which produces this error. Upgrade to version 1.0.13
as found here
通过将jar文件添加到类路径(而不是包含它们的文件夹)解决了问题
The various constructors of JFrame
do important initialisation work, that any JFrame
requires. Therefore, every JFrame
that is ever created must have one of those constructors called. But because an ODESolver
is also a JFrame
, that applies to ODESolver
objects too.
Fortunately, the Java language enforces this. We can't create an ODESolver
, without one of the JFrame
constructors getting called. The way it enforces it is by requiring every ODESolver
constructor to be mapped to a JFrame
constructor.
When we create an ODESolver
, one of the ODESolver
constructors will get called. But that constructor must specify which JFrame
constructor will get called. The way it does that is by doing one of the following.
JFrame
constructor to use, via a call to super()
, with or without some arguments; ODESolver
constructor, via a call to this()
, with or without some arguments. In either case, the call to super()
or this()
must be the first line of the ODESolver
constructor.
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