Scrollbar doesn't show up on the panel while dynamically adding JTextFields

Question

I have a dynamic user iterface, where the JTextFields are added dynamically to a JPanel within the JFrame upon the click of a JButton. How do I use the JScrollPane so that the Vertical Scroll bar shows up for the JPanel as soon added TextFields go out of range? The Panel has a null layout coz I want the textfields at specific positions on the panel. The problem lies in showing the Vertical scroll bar once the text fields in the JPanel exceeds the Panel's size. The scrolls don't seem to show up. Please help!
public Scenario() // Constructor
textPanel = new JPanel();
textPanel.setLayout(null);
textPanel.setSize(508, 520);
textPanel.setLocation(10,10);
//..........lines of code
public void addComponent(String text)
j = j + 30;
i = i+1;
String lineno = Integer.toString(i) + ".";
field = new JLabel(lineno);
field.setBounds(90,j,20,24);
textPanel.add(field);
if (addline){
content = new JTextField(text);
content.setBounds(108,j,400,24);
content.setBackground(new Color(255,255,255));
textPanel.add(content);
addline = false;
invscenario = false;
else if(invscenario) {
content = new JTextField(text);
content.setBounds(108,j,50,24);
content.setEditable(false);
textPanel.add(content);
try{
if (content.getText().length()!= 0)
Statement statement1 = conn.createStatement();
String query1 = "SELECT * FROM scenario " + "WHERE scenario_num LIKE '" + text + "'";
rs = statement1.executeQuery(query1);
rs.next();
int recordNumber = rs.getInt(1);
if(recordNumber != 0)
labelcontent = new JLabel(rs.getString(3));
labelcontent.setBounds(165,j,100,24);
textPanel.add(labelcontent);
}// end try
catch(SQLException e)
System.out.println(e);
invscenario = false;
addline = false;
scrollPane = new JScrollPane(textPanel);
scrollPane.add(textPanel);
contentPane.add(scrollPane);
contentPane.repaint();
show();

Answer 1

I guess since you don't have a layoutmanager you have to set the viewport dimensions of your JScrollPane manually.
Try something like
scrollPane.getViewport().reshape(....);
zk