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Adding a JScrollPane to an existing JPanel

I am trying to add a JScrollPane (createTeamScrollPane) to a JPanel (createTeamPanel) that I have. I have a frame, with a BorderLayout with the NORTH portion being used by a JPanel called tabMenu, and then the CENTER portion I would like my 'createTeamPanel' to have this scrolling ability as it will have more content than what I can fit on the screen at once. I am then adding both panels to the frame. Currently the code as is runs but the window appears blank. Once resizing the window, I then see the 3 buttons in the NORTH portion of my frame (why is this happening?) and when I click on 'Create Team' it brings up the list of JLabels and JButtons I expect but I don't see any scrolling bars?
public static void main (String args[]) {
JFrame frame = new JFrame();
frame.setTitle("v0.01");
frame.setSize(800, 800);
//frame.setLayout(null);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel mainPanel = new JPanel();
mainPanel.setLayout(new BorderLayout());
JPanel tabMenu = new JPanel();
JPanel createTeamPanel = new JPanel();
createTeamPanel.setLayout(new BoxLayout(createTeamPanel, BoxLayout.Y_AXIS));
createTeamPanel.setSize(800, 700);
createTeamPanel.setVisible(showCreateTeamPanel);
createTeamPanel.setBackground(Color.gray);
JScrollPane createTeamScrollPane = new JScrollPane(createTeamPanel);
createTeamScrollPane.setBounds(50, 50, 200, 500);
createTeamScrollPane.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
createTeamScrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);
createTeamScrollPane.setPreferredSize(new Dimension(500,500));
//createTeamPanel.add(createTeamScrollPane);
List<Player> teamList = MockTeams.initTeam();
int xcoord = 100;
int ycoord = 50;
for(Player player : teamList) {
JLabel label = new JLabel(player.getName());
label.setBounds(xcoord, ycoord, Constants.buttonWidth, Constants.buttonHeight);
JButton addToTeamBtn = new JButton("Add to team");
addToTeamBtn.setBounds(xcoord + 100, ycoord, Constants.buttonWidth, Constants.buttonHeight);
addToTeamBtn.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
myTeam.add(player);
addToTeamBtn.setEnabled(false);
}
});
createTeamPanel.add(label);
//createTeamFrame.add(label);
createTeamPanel.add(addToTeamBtn);
//createTeamFrame.add(addToTeamBtn);
ycoord += 50;
}
JButton createTeamBtn = new JButton("Create Team");
createTeamBtn.setBounds(0,0,150,20);
createTeamBtn.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
//Hide/Show Create team panel
if (!showCreateTeamPanel) {
showCreateTeamPanel = true;
createTeamPanel.setVisible(showCreateTeamPanel);
} else {
showCreateTeamPanel = false;
createTeamPanel.setVisible(showCreateTeamPanel);
}
}
});
JButton manageTeamBtn = new JButton("Team Statistics");
manageTeamBtn.setBounds(100,150,150,40);
JButton resetBtn = new JButton("Reset Season");
resetBtn.setBounds(100,200,150,40);
tabMenu.add(createTeamBtn);
tabMenu.add(manageTeamBtn);
tabMenu.add(resetBtn);
mainPanel.add(tabMenu, BorderLayout.NORTH);
mainPanel.add(createTeamPanel, BorderLayout.CENTER);
frame.add(mainPanel);
}
Expected result is to see a scrolling ability on the createTeamPanel but it is not there.

Fixed: I was able to add the JScrollPane to the mainPanel with:
mainPanel.add(createTeamScrollPane, BorderLayout.CENTER);

Keep BoxLayout From Expanding Children

I want to stack some JComponents vertically inside a JPanel so they stack at the top and any extra space is at the bottom. I'm using a BoxLayout. The components will each contain a JTextArea that should allow the text to wrap if necessary. So, basically, I want the height of each of these components to be the minimum necessary for displaying the (possibly wrapped) text.
Here's a contained code example of what I'm doing:
import javax.swing.*;
import java.awt.*;
public class TextAreaTester {
public static void main(String[] args){
new TextAreaTester();
}
public TextAreaTester(){
JFrame frame = new JFrame();
JPanel panel = new JPanel();
panel.setLayout(new BoxLayout(panel,BoxLayout.PAGE_AXIS));
panel.setPreferredSize(new Dimension(100,400));
for(int i = 0; i<3; i++){
JPanel item = new JPanel(new BorderLayout());
JTextArea textarea = new JTextArea("this is a line of text I want to wrap if necessary");
textarea.setWrapStyleWord(true);
textarea.setLineWrap(true);
textarea.setMaximumSize( textarea.getPreferredSize() );
item.add(textarea,BorderLayout.NORTH);
panel.add(item);
}
panel.add(Box.createGlue());
frame.add(panel);
frame.setVisible(true);
frame.pack();
}
}
The child JPanels are expanding to fill the vertical space. I tried using glue because I thought that's what glue was for, but it seems to do nothing at all. Any help?
Note: I have found questions that look almost identical, but none with answers I can apply.

One solution: nest JPanels with the outer JPanel using Borderlayout and adding the BoxLayout using JPanel to this one BorderLayout.NORTH, also known as BorderLayout.PAGE_START:
Edit for Kleopatra:
import javax.swing.*;
import java.awt.*;
public class TextAreaTester {
public static void main(String[] args) {
new TextAreaTester();
}
public TextAreaTester() {
JFrame frame = new JFrame();
JPanel panel = new JPanel();
panel.setLayout(new BoxLayout(panel, BoxLayout.PAGE_AXIS));
// panel.setPreferredSize(new Dimension(100,400));
for (int i = 0; i < 3; i++) {
JPanel item = new JPanel(new BorderLayout());
// item.setLayout(new BoxLayout(item,BoxLayout.LINE_AXIS));
JTextArea textarea = new JTextArea(
"this is a line of text I want to wrap if necessary", 3, 35);
textarea.setWrapStyleWord(true);
textarea.setLineWrap(true);
// textarea.setMaximumSize(textarea.getPreferredSize());
// item.setMaximumSize( item.getPreferredSize() );
item.add(new JScrollPane(textarea), BorderLayout.NORTH);
panel.add(item);
}
panel.add(Box.createGlue());
JPanel mainPanel = new JPanel(new BorderLayout()) {
private final int prefW = 100;
private final int prefH = 400;
#Override
public Dimension getPreferredSize() {
return new Dimension(prefW, prefH);
}
};
// mainPanel.setPreferredSize(new Dimension(100, 400));
mainPanel.add(panel, BorderLayout.PAGE_START);
frame.add(mainPanel);
frame.setVisible(true);
// frame.getContentPane().add(jp);
frame.pack();
}
}

Alternatively, you can use Box.Filler. Just replace your call to panel.add(Box.createGlue()) with
panel.add(new Box.Filler(new Dimension(0, 0),
new Dimension(0, Short.MAX_VALUE),
new Dimension(0, Short.MAX_VALUE)));
If you want to achieve the same for a horizontal layout, just use Short.MAX_VALUE for width instead of height in the Dimension call.

Adding ScrollPane to JTextArea

I am working on a project for my college course. I was just wondering if anyone knew how to add a scrollBar to a JTextArea. At present I have the GUI laid out correctly, the only thing missing is the scroll bar.
This is what the GUI looks like. As you can see on the second TextArea I would like to add the Scrollbar.
This is my code where I create the pane. But nothing seems to happen... t2 is the JTextArea I want to add it to.
scroll = new JScrollPane(t2);
scroll.setBounds(10,60,780,500);
scroll.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
Any help would be great, thanks!

The Scroll Bar comes when your text goes beyond the bounds of your view area. Don't use Absolute Positioning, for such a small talk at hand, always prefer Layout Managers, do read the first para of the first link, to know the advantage of using a Layout Manager.
What you simply need to do is use this thingy :
JTextArea msgArea = new JTextArea(10, 10);
msgArea.setWrapStyleWord(true);
msgArea.setLineWrap(true);
JScrollPane msgScroller = new JScrollPane();
msgScroller.setBorder(
BorderFactory.createTitledBorder("Messages"));
msgScroller.setViewportView(msgArea);
panelObject.add(msgScroller);
Here is a small program for your understanding :
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class JTextAreaScroller
{
private JTextArea msgArea;
private JScrollPane msgScroller;
private JTextArea logArea;
private JScrollPane logScroller;
private JButton sendButton;
private JButton terminateButton;
private Timer timer;
private int counter = 0;
private String[] messages = {
"Hello there\n",
"How you doing ?\n",
"This is a very long text that might won't fit in a single line :-)\n",
"Okay just to occupy more space, it's another line.\n",
"Don't read too much of the messages, instead work on the solution.\n",
"Byee byee :-)\n",
"Cheers\n"
};
private ActionListener timerAction = new ActionListener()
{
#Override
public void actionPerformed(ActionEvent ae)
{
if (counter < messages.length)
msgArea.append(messages[counter++]);
else
counter = 0;
}
};
private void displayGUI()
{
JFrame frame = new JFrame("Chat Messenger Dummy");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel contentPane = new JPanel();
contentPane.setLayout(new BorderLayout(5, 5));
JPanel centerPanel = new JPanel();
centerPanel.setLayout(new GridLayout(0, 1, 5, 5));
logArea = new JTextArea(10, 10);
logArea.setWrapStyleWord(true);
logArea.setLineWrap(true);
logScroller = new JScrollPane();
logScroller.setBorder(
BorderFactory.createTitledBorder("Chat Log"));
logScroller.setViewportView(logArea);
msgArea = new JTextArea(10, 10);
msgArea.setWrapStyleWord(true);
msgArea.setLineWrap(true);
msgScroller = new JScrollPane();
msgScroller.setBorder(
BorderFactory.createTitledBorder("Messages"));
msgScroller.setViewportView(msgArea);
centerPanel.add(logScroller);
centerPanel.add(msgScroller);
JPanel bottomPanel = new JPanel();
terminateButton = new JButton("Terminate Session");
terminateButton.addActionListener(new ActionListener()
{
#Override
public void actionPerformed(ActionEvent ae)
{
if (timer.isRunning())
timer.stop();
else
timer.start();
}
});
sendButton = new JButton("Send");
bottomPanel.add(terminateButton);
bottomPanel.add(sendButton);
contentPane.add(centerPanel, BorderLayout.CENTER);
contentPane.add(bottomPanel, BorderLayout.PAGE_END);
frame.setContentPane(contentPane);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
timer = new Timer(1000, timerAction);
timer.start();
}
public static void main(String... args)
{
EventQueue.invokeLater(new Runnable()
{
#Override
public void run()
{
new JTextAreaScroller().displayGUI();
}
});
}
}
Here is the outcome of the same :

The scroll bar by default will only be shown when the content overfills the available viewable area
You can change this via the JScrollPane#setVerticalScrollBarPolicy method, passing it ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS

JScrollPane won't work

Hey guys I wanted to create a JScrollPane but it won't work... and I don't know why... here's my code...
public class test extends JFrame{
public test(){
setSize(1000,600);
}
private static JButton[] remove;
private static JPanel p = new JPanel();
public static void main(String[]args){
p.setLayout(null);
JFrame t=new test();
remove = new JButton[25];
for(int i=0;i<25;i++){
remove[i]=new JButton("Remove");
remove[i].setBounds(243,92+35*i,85,25);
p.add(remove[i]);
}
JScrollPane scrollPane = new JScrollPane(p);
scrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);
t.add(scrollPane);
t.setVisible(true);
}
Umm and Im pretty sure the frame isn't big enough for these 25 buttons... But if i delete that p.setLayout(null); A horizontal scroll bar will be created automatically... I don't really know what is wrong with my code... Pls help thank you very much!

You need to set p's preferredSize for this to work.
p.setPreferredSize(new Dimension(800, 2000));
Or you could have p extend JPanel and then override the getPreferredSize() method to return the proper dimension.
And I agree -- get rid of your null layouts. Learn about and use the layout managers if you want to use Swing correctly and have robust Swing GUI's.
e.g.,
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Foo extends JFrame {
private static final int BUTTON_COUNT = 25;
public static void main(String[] args) {
JPanel btnPanel = new JPanel(new GridLayout(0, 1, 0, 20));
btnPanel.setBorder(BorderFactory.createEmptyBorder(20, 20, 20, 20));
AbstractAction removeAction = new AbstractAction("Remove") {
#Override
public void actionPerformed(ActionEvent evt) {
JButton src = (JButton) evt.getSource();
JPanel container = (JPanel) src.getParent();
container.remove(src);
container.revalidate();
container.repaint();
}
};
for (int i = 0; i < BUTTON_COUNT; i++) {
JButton removeBtn = new JButton(removeAction);
btnPanel.add(removeBtn);
}
JPanel borderPanel = new JPanel(new BorderLayout());
borderPanel.add(btnPanel, BorderLayout.NORTH);
JScrollPane scrollpane = new JScrollPane(borderPanel,
JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
scrollpane.setPreferredSize(new Dimension(400, 800));
JFrame frame = new JFrame("Foo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(scrollpane);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
}

The issue is that a scroll pane checks the component inside it for a "preferred size" so a pane with a null layout has a preferred size of (0,0). Which it ignores.
You should do something along the lines of:
p.setPreferredSize(1000,600);
And you should see some scroll bars appear, I'm not sure how accurate they will be though.

Items not Appearing in New Frame in Java

I'm building a JFrame that will eventually display the output of a program that has a variable number of sections in it. I have parsed the output but displaying it in the frame is a problem.
When the frame appears, it is completely empty with the exception of the scroll pane. How do I get these labels to show up?
public class OutputPanel extends JFrame {
public OutputPanel(Vector parsedOutput) {
this.setTitle("Output");
this.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
JScrollPane scrollPane = new JScrollPane();
Iterator<Vector> outputIter = parsedOutput.iterator();
while(outputIter.hasNext()) {
Vector section = outputIter.next();
JLabel sectionLabel = new JLabel((String)section.get(0));
System.out.println((String)section.get(0));
scrollPane.add(sectionLabel);
}
this.add(scrollPane);
this.pack();
this.setVisible(true);
}
}

You shouldn't add components to the scrollPane
scrollPane.add(sectionLabel);
but rather add them to a separate panel, and either use
scrollPane = new JScrollPane(thePanel);
or
scrollPane.setViewportView(thePanel);
Example:
import java.awt.GridLayout;
import java.util.Vector;
import javax.swing.*;
class Test {
public static void main(String[] args) {
new OutputPanel(null);
}
}
class OutputPanel extends JFrame {
public OutputPanel(Vector parsedOutput) {
this.setTitle("Output");
this.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
JPanel content = new JPanel(new GridLayout(0, 1));
for (int i = 0; i < 100; i++) {
JLabel sectionLabel = new JLabel("hello " + i);
content.add(sectionLabel);
}
JScrollPane scrollPane = new JScrollPane(content);
this.add(scrollPane);
this.pack();
this.setVisible(true);
}
}
Produces:

You should use setViewPortView() with a container instead of add() for JScrollPane.
Try this.
public class OutputPanel extends JFrame {
public OutputPanel(Vector parsedOutput) {
this.setTitle("Output");
this.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
JScrollPane scrollPane = new JScrollPane();
Iterator<Vector> outputIter = parsedOutput.iterator();
JPanel panel = new JPanel();
panel.setLayout(new FlowLayout());
scrollPane.setViewportView(panel);
while(outputIter.hasNext()) {
Vector section = outputIter.next();
JLabel sectionLabel = new JLabel((String)section.get(0));
System.out.println((String)section.get(0));
panel.add(sectionLabel);
}
this.add(scrollPane);
this.pack();
this.setVisible(true);
}
}