JScrollPanel does not appear

[Fredwurst]

I've a little problem with the JScrollPanel. It does not appear. I tried a lot of configurations and possible solutions to see them, but nothing works. So, here is a little code fragment which describes my problem:

<font size=2.5>
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import java.util.*;
public class TestFrame
{
  public JButton button;
  public PicturePanel picturePanel;
  public JFrame jFrame = new JFrame();
  public JScrollPane scrollPane;
  public JSplitPane jSplitpane;
  public JPanel panel = new JPanel();
  public static void main(String[] args)
  {
    TestFrame frame = new TestFrame();
  }
  public TestFrame()
  {
    jFrame.setSize(300,300);
    jFrame.setLocation(300,300);
    picturePanel = new PicturePanel();
    picturePanel.setSize(1000,1000);
    scrollPane = new JScrollPane(picturePanel);
    button = new JButton();
    button.setText("Step");
    jSplitpane = new JSplitPane(JSplitPane.VERTICAL_SPLIT,button,scrollPane);
    jSplitpane.setContinuousLayout(true);
    jSplitpane.setPreferredSize(new Dimension(1000,1000));
    jFrame.getContentPane().add(jSplitpane,BorderLayout.CENTER);
    jFrame.setVisible(true);
    button.addActionListener(new java.awt.event.ActionListener() {
      public void actionPerformed(ActionEvent e) {
        button_actionPerformed(e);
      }
    });
  }
  void button_actionPerformed(ActionEvent e) {
    this.picturePanel.repaint();
  }
}

class PicturePanel extends JPanel
{
  private int x1 = 0;
  private int x2 = 0;
  private int y1 = 0;
  private int y2 = 0;
  private Random r = new Random();
  private ArrayList arrayList = new ArrayList();
  public void PicturePanel()
  {
    this.setBackground(Color.black);
    this.setSize(1000,1000);
  }
  public void paintComponent(Graphics g)
  {
    super.paintComponent(g);
    g.setColor(Color.white);
    paintLine(g);
  }
  public void paintLine(Graphics g)
  {
    ArrayList v = new ArrayList();
    v = createNewData();
    arrayList.add(v);
    for (int n=0;n<arrayList.size()-1;n++)>
    {
      v = (ArrayList) arrayList.get(n);
      x1 = ((Integer) v.get(0)).intValue();
      y1 = ((Integer) v.get(1)).intValue();
      x2 = ((Integer) v.get(2)).intValue();
      y2 = ((Integer) v.get(3)).intValue();
      g.drawLine(x1,y1,x2,y2);
    }
  }
  public ArrayList createNewData()
  {
    ArrayList v = new ArrayList();
    for (int n=0;n<4;n++){
      Integer a = new Integer((int)(r.nextInt(1000)));
      v.add(a);
    }
    return v;
  }
}

Thanks for help ...
Fredwurst
(edited by Cindy to get the font big enough to READ)

[This message has been edited by Cindy Glass (edited September 03, 2001).]

[Cindy Glass]

Fredwurst,
The Java Ranch has thousands of visitors every week, many with surprisingly similar names. To avoid confusion we have a naming convention, described at "JavaRanch Naming Policy" . We require names to have at least two words (not just letters), separated by a space, and strongly recommend that you use your full real name. We want to get to know you as a Professional. Please choose a new name which meets the requirements and re-register.
Cindy

[Hineck Fredwurst]

Sorry for the short name ... i didn't read the JavaRanch Naming Policy carefully. I reregistered now with my full name ...
Fredwurst

[Paul Stevens]

Try setting the scrollbar policy when you create your JScrollPane to always on.

[Hineck Fredwurst]

I figured it out. Now it works. Have a look on the following code:
<CODE>
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import java.util.*;
public class TestFrame
{
public JButton button;
public JFrame jFrame = new JFrame();
public JScrollPane scrollPane;
public JSplitPane jSplitpane;
public PaintPanel panel;
public static void main(String[] args)
{
TestFrame frame = new TestFrame();
}
public TestFrame()
{
jFrame.setSize(300,300);
jFrame.setLocation(300,300);
panel = new PaintPanel();
panel.setBackground(Color.black);
panel.setSize(1000,1000);
scrollPane = new JScrollPane(panel);
panel.setPreferredSize(new Dimension(1000,1000));
button = new JButton();
button.setText("Step");
jSplitpane = new JSplitPane(JSplitPane.VERTICAL_SPLIT,button,scrollPane);
jSplitpane.setContinuousLayout(true);
jFrame.getContentPane().add(jSplitpane);
jFrame.setVisible(true);
button.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(ActionEvent e) {
button_actionPerformed(e);
}
});
}
void button_actionPerformed(ActionEvent e) {
this.panel.repaint();
}
}
class PaintPanel extends JPanel
{
private int x1 = 0;
private int x2 = 0;
private int y1 = 0;
private int y2 = 0;
private Random r = new Random();
private ArrayList arrayList = new ArrayList();
protected void paintComponent(Graphics g)
{
super.paintComponent(g);
g.setColor(Color.white);
paintLine(g);
}
protected void paintLine(Graphics g)
{
ArrayList v = new ArrayList();
v = createNewData();
arrayList.add(v);
for (int n=0;n<arrayList.size()-1;n++)>
{
v = (ArrayList) arrayList.get(n);
x1 = ((Integer) v.get(0)).intValue();
y1 = ((Integer) v.get(1)).intValue();
x2 = ((Integer) v.get(2)).intValue();
y2 = ((Integer) v.get(3)).intValue();
g.drawLine(x1,y1,x2,y2);
}
}
public ArrayList createNewData()
{
ArrayList v = new ArrayList();
for (int n=0;n<4;n++){
Integer a = new Integer((int)(r.nextInt(1000)));
v.add(a);
}
return v;
}
}
</CODE>
Thanks,
Fredwurst