Repaint() for JPanels

Question

HI ALL,
I am doing a line plot of image data, and displaying it on a JPanel.
In my App, I added some buttons for I can transition between the plots.
I can grab all the data at once and display all in separate tabs, but
when I changed it to this buttons format, the plot never updates.
Here is my button function to update the panel.
     myPrevButton.addActionListener(new ActionListener() {
          public void actionPerformed(ActionEvent ae) {
                    try{
                         p = (Plotable)myPlotables.elementAt(currentPlot-2);
                    myMeanPlotPanel = new XYPlotJPanel(p);
               p = (Plotable)list.nextElement();
                         currentPlot = myPlotables.indexOf(p);
          mySDPlotPanel = new XYPlotJPanel(p);
                         myMainPanel.repaint();
          } catch (NotEnoughDataException nede){
               MsgPopup msg = new MsgPopup(LocalizedError.constructFormattedErrorString(nede));
               msg.show();
When I read the images, I use a vector to order the images, and "list" is an enumertion variable in this function.
The mainPanel holds both subpanels. Now the app will show only the first plot, but will not update any other plots. I have tried repaint() all panels before, it did not work.
Does anyone know how to get this to update or replot,refresh, ...or etc....?
I have not ideas now.
Thanks!

Answer 1

import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import java.util.*;
import java.util.List;
import javax.swing.*;
public class SelectingGraphs {
  static int plotIndex = 0;
  public static void main(String[] args) {
    float[] data1 = {
      1.2f, 2.0f, 3.7f, 4f, 2.9f, 4.9f, 3.1f, 4.02f
    float[] data2 = {
      29f, 18.2f, 75f, 34f, 92f, 15f, 50.9f, 42.3f
    float[] data3 = {
      90f, 44f, 53.7f, 67.2f, 49.2f, 79f, 80.3f, 55.2f
    final float[][] allData = {
      data1, data2, data3
    Plot
      plot1 = new Plot(),
      plot2 = new Plot(),
      plot3 = new Plot();
    final Plot[] plots = {
      plot1, plot2, plot3
    for(int i = 0; i < plots.length; i++)
      for(int j = 0; j < allData.length; j++)
plots[i].plot(allData[i][j]);
final JPanel panel = new JPanel();
panel.add(plot1);
// south panel
final JButton
lastButton = new JButton("last"),
nextButton = new JButton("next");
ActionListener l = new ActionListener() {
public void actionPerformed(ActionEvent e) {
JButton button = (JButton)e.getSource();
panel.remove(plots[plotIndex % 3]);
if(button == lastButton) {
--plotIndex;
if(plotIndex < 0)
plotIndex = 2;
if(button == nextButton)
++plotIndex;
panel.add(plots[plotIndex % 3]);
panel.revalidate();
panel.repaint();
lastButton.addActionListener(l);
nextButton.addActionListener(l);
JPanel southPanel = new JPanel();
southPanel.add(lastButton);
southPanel.add(nextButton);
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.getContentPane().add(panel);
f.getContentPane().add(southPanel, "South");
f.setSize(400,300);
f.setLocation(400,300);
f.setVisible(true);
class Plot extends JPanel {
float PAD = 25;
List dataList;
public Plot() {
dataList = new ArrayList();
setBackground(Color.white);
setPreferredSize(new Dimension(200,200));
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D)g;
float width = getWidth();
float height = getHeight();
float xStep = (width - 2*PAD)/(dataList.size() - 1);
float x = PAD;
float y;
// scale data
float max = ((Float)Collections.max(dataList)).floatValue();
float min = ((Float)Collections.min(dataList)).floatValue();
float vertSpace = height - 2*PAD;
float yOffset = height - PAD;
float yDataOffset = (min >= 0 ? min : max > 0 ? 0 : max);
float scale = vertSpace/(max - min);
float yOrigin = yOffset + (min > 0 ? 0 : max > 0 ? scale*min : - vertSpace);
// draw ordinate
g2.draw(new Line2D.Float(PAD, PAD, PAD, yOffset));
// draw abcissa
g2.draw(new Line2D.Float(PAD, yOrigin, width - PAD, yOrigin));
// label ordinate limits
g2.drawString(String.valueOf(max), 10, PAD - 10);
g2.drawString(String.valueOf(min), 10, yOffset + PAD/2);
g2.setStroke(new BasicStroke(4f));
g2.setPaint(Color.red);
for(int j = 0; j < dataList.size(); j++) {
y = yOrigin - scale * (((Float)dataList.get(j)).floatValue() - yDataOffset);
g2.draw(new Line2D.Float(x, y, x, y));
x += xStep;
protected void plot(float input) {
dataList.add(new Float(input));
repaint();