Develop Reference

How to set a ScrollBar at the top of a JPanel

I am trying to insert a JScrollPane in a JPanel. By default, when I open the panel, the scrollbar is set at the bottom. What I want is the opposite, to set it at the top of the pannel.
I have tried the commands scrollBar.getVerticalScrollBar().setValue(0) and JPanel.add(scrollBar, BorderLayout.NORTH), but thet do not work.
The code I have is:
JPanel panel=new JPanel();
texto = new ReportPanel();
texto.setEditable(false);
panel.add(texto, BorderLayout.NORTH);
JScrollPane scrollBar=new JScrollPane(panel, JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED, JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
this.add(scrollBar);

Why JTextArea doesn't work with JPanel?

Why when I add JTextArea to JPanel it doesn't work? When I use JButton instead of JTextArea everything works corectly. Why doesn't JTextArea work with JPanel but with JFrame does?
public class Searching extends JPanel {
private JPanel searchPanel;
private JTextArea addMedicament;
public Searching(){
searchPanel = new JPanel();
searchPanel.setLayout(new GridLayout(1,1));
setBackground(Color.BLUE);
addMedicament = new JTextArea();
searchPanel.add(addMedicament);
this.add(searchPanel);
}
}

A text area will work fine with a panel.
Try creating the text area as follows:
JTextArea textArea = new JTextArea(5, 20);
JScrollPane = new JScrollPane( textArea );
panel.add( scrollPane );
Now the text area will be created with a preferred size. As the data is changed scrollbars will appear/disappear as required because the problem is with your code and the context of how you use your code, not the panel or text area.
If this doesn't help then post a proper SSCCE that demonstrates the problem.

Adding buttons and scrollable panel to a tab - Java

I'm trying to build a Java GUI where among other things there will be several tabs.
In one of the tabs I want to have both a scrollable JTextArea, and also some buttons at the top/bottom that interacts with the JTextArea. I can't figure out how to get both into the same tab, I'm either getting the buttons and a non-scrollable jtextarea, or just the scrollable jtextarea. I also don't want to display the button in the other tabs. Here is my code:
private final JTextArea music = new JTextArea();
private final JTextArea button = new JTextArea();
private final JTextArea test = new JTextArea();
private final JTabbedPane tab = new JTabbedPane();
private JTable table;
music.append(newPlaylist.toString());
JFrame frame = new JFrame("GUI");
frame.setTitle("Music File Organiser");
JPanel panel = new JPanel();
panel.setLayout(new FlowLayout(FlowLayout.CENTER));
JButton button1 = new JButton("Hello");
JButton button2 = new JButton("Sort by Album Title");
JButton button3 = new JButton("Sort by Track Title");
button1.addActionListener(new ActionListener() {code};
button2.addActionListener(new ActionListener() {code};
button3.addActionListener(new ActionListener() {code};
panel.add(music);
panel.add(button1);
panel.add(button2);
panel.add(button3);
JScrollPane scroll = new JScrollPane(panel);
JScrollPane scroll2 = new JScrollPane(table);
tab.add("Music Files", scroll);
tab.add("Table", scroll2);
this.add(tab);
frame.setLocationRelativeTo(null);
this.setSize(1200, 1000);
this.setVisible(true);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
The tab in mind is the first one. How do I add buttons to "scroll"? The way I'm trying it here is to add the JTextArea "music" into panel, then adding the buttons to the same panel, then adding the panel to a JScrollPane, and then adding the JScrollPane to tab. Any help would really be appreciated.

Encapsulate your visual elements into child Panels.
JPanel buttonPanel = new JPanel(); //panel for buttons.
buttonPanel.add(button1);
buttonPanel.add(button2);
buttonPanel.add(button3);
JScrollPane scroll = new JScrollPane(music); //scrollable pane for JTextArea
panel.add(buttonPanel);
panel.add(scroll); //add sub-components to panel for tab
/*here you would add some layout code to fit the panel and scroll into the associated spaces */
tab.add("Music Files", panel); //add panel to tab

You can do something like this:
JPanel tab = new JPanel()
JPanel tabWithButtons = new JPanel()
JPanel tabWithScrollPanel = new JPanel()
tab.add(tabWithScrollPanel)
tab.add(tabWithButtons)
IMO this is better way, because I assume that buttons shouldn't be included in JScrollPane and they should be visible all the time
Of course, you have to add all elements to proper JPanels.
Also, you can try with width/height settings of panel which contains all your elements, maybe ScrollArea panel is to big?

Adding a Scrollable JTextArea (Java)

I am trying to add a scroll bar to a JTextArea. Would someone please tell me what I did wrong with the code below?
JFrame frame = new JFrame ("Test");
JTextArea textArea = new JTextArea ("Test");
JScrollPane scrollV = new JScrollPane (textArea);
JScrollPane scrollH = new JScrollPane (textArea);
scrollV.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
scrollH.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
frame.setVisible (true);
Thank you in advance.
EDIT: I fixed the code with the Adel Boutros' advice below.
//FRAME
JFrame frame = new JFrame ("Test");
frame.setSize(500,500);
frame.setResizable(false);
//
//TEXT AREA
JTextArea textArea = new JTextArea("TEST");
textArea.setSize(400,400);
textArea.setLineWrap(true);
textArea.setEditable(false);
textArea.setVisible(true);
JScrollPane scroll = new JScrollPane (textArea);
scroll.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
scroll.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
frame.add(scroll);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

It doesn't work because you didn't attach the ScrollPane to the JFrame.
Also, you don't need 2 JScrollPanes:
JFrame frame = new JFrame ("Test");
JTextArea textArea = new JTextArea ("Test");
JScrollPane scroll = new JScrollPane (textArea,
JScrollPane.VERTICAL_SCROLLBAR_ALWAYS, JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
frame.add(scroll);
frame.setVisible (true);

Open design view
Right click to textArea
open surround with option
select "...JScrollPane".

A scroll pane is a container which contains another component. You can't add your text area to two different scroll panes. The scroll pane takes care of the horizontal and vertical scroll bars.
And if you never add the scroll pane to the frame, it will never be visible.
Read the swing tutorial about scroll panes.

You don't need two JScrollPanes.
Example:
JTextArea ta = new JTextArea();
JScrollPane sp = new JScrollPane(ta);
// Add the scroll pane into the content pane
JFrame f = new JFrame();
f.getContentPane().add(sp);

JScrollPane for a panel containing a set of labels with BoxLayout

I'd like to use a JScrollPane for a panel which has an arbitrary list of labels in it using box layout. I'm trying to get it so that the scrollbar would appear if there were too many items (labels) to display.
I tried adding a JScrollPane to the panel and then add the labels but then I don't see any scroll bar.
Any ideas?
TIA

For this kind of thing, you'd normally use a JList or JTable (if you need custom rendering).

Make sure that you call validate() or revalidate() on the JScrollPane after adding an item, to force the preferred size of the panel to be recalculated.

Here's how I did it.
JPanel midPanel = new JPanel();
midPanel.setLayout(new BoxLayout(midPanel, BoxLayout.Y_AXIS));
midPanel.add(new JLabel("<html><u>Label</u>"));
Box box = Box.createVerticalBox();
for (Item item : data.getInventory()) {
inventory.add(box.add(new JLabel(item.getName())));
}
JScrollPane jscrlpBox = new JScrollPane(box);
midPanel.add(jscrlpBox);
add(midPanel, BorderLayout.CENTER);
From:
http://www.java2s.com/Code/Java/Swing-JFC/JScrollPanetoholdscrollablecomponent.htm

Did you remember to set the preferred size of the content panel?
final JFrame frame = new JFrame("Scroll Demo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
final Box textArea = Box.createVerticalBox();
final JScrollPane textAreaScroll = new JScrollPane(textArea);
textAreaScroll.setPreferredSize(new Dimension(80,150)); /* essential! */
JButton addButton = new JButton("ADD");
addButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
textArea.add(new JLabel("abc"));
textArea.revalidate();
}
});
frame.getContentPane().add(textAreaScroll, BorderLayout.SOUTH);
frame.getContentPane().add(Box.createRigidArea(new Dimension(10,10)), BorderLayout.CENTER);
frame.getContentPane().add(addButton, BorderLayout.NORTH);
frame.pack();
frame.setVisible(true);
In this example, the scroll bar works correctly, but if you remove the line marked as "essential", it will not work anymore.