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Java Layout with Component always in Top Right

The primary GUI of my application is composed of a JDesktopPane at the CENTER of a frame's content pane using a BorderLayout. I am hoping to have a component placed in the top right of the screen that still allows the user to drag JInternalFrames within the space to the left and and bottom of this component.
Setting the component to the NORTH or EAST of the BorderLayout seems to fill the entire space. I am thinking BorderLayout may not be the best layout manager for what I am trying to accomplish? Any suggestions on a better approach?

Check out the OverlayLayout. It allows you to stack components on top of one another.
You need to manipulate the setAlignmentX(..) and setAlignmentY(...)` methods to get the layout you want. It is not always intuitive how these alignments work together but setting the component to the top/left is relatively easy.
Here is a little demo for you to play with:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.*;
public class OverlayLayoutTest extends JPanel
implements ActionListener
{
JPanel green;
JPanel red;
JLabel greenLabel;
JLabel redLabel;
JComboBox greenAlignmentX;
JComboBox greenAlignmentY;
JComboBox redAlignmentX;
JComboBox redAlignmentY;
public OverlayLayoutTest()
{
setLayout( new BorderLayout(10, 10) );
add(createNorthPanel(), BorderLayout.NORTH);
add(createCenterPanel(), BorderLayout.CENTER);
add(createSouthPanel(), BorderLayout.SOUTH);
}
private JPanel createNorthPanel()
{
JPanel panel = new JPanel();
panel.add( new JLabel("Green:") );
greenLabel = new JLabel();
panel.add( greenLabel );
panel.add( new JLabel("Red:") );
redLabel = new JLabel();
panel.add( redLabel );
return panel;
}
private JPanel createCenterPanel()
{
JPanel panel = new JPanel();
panel.setLayout( new OverlayLayout(panel) );
panel.setBackground( Color.ORANGE );
panel.setPreferredSize( new Dimension(200, 200) );
red = new JPanel();
red.setBackground( Color.RED );
red.setPreferredSize( new Dimension(50, 50) );
red.setMaximumSize( red.getPreferredSize() );
red.setMinimumSize( red.getPreferredSize() );
panel.add( red );
green = new JPanel();
green.setBackground( Color.GREEN );
green.setPreferredSize( new Dimension(100, 100) );
green.setMaximumSize( green.getPreferredSize() );
green.setMinimumSize( green.getPreferredSize() );
panel.add( green );
JPanel wrap = new JPanel();
wrap.add( panel );
return wrap;
}
private JPanel createSouthPanel()
{
JPanel panel = new JPanel( new GridLayout(1, 0, 10, 10) );
JPanel green = new JPanel(new GridLayout(0, 2, 5, 5) );
green.setBorder( new TitledBorder("Green Alignment") );
green.add( new JLabel("X Alignment:") );
greenAlignmentX = createComboBox();
green.add( greenAlignmentX );
green.add( new JLabel("Y Alignment:") );
greenAlignmentY = createComboBox();
green.add( greenAlignmentY );
panel.add( green );
JPanel red = new JPanel(new GridLayout(0, 2, 5, 5) );
red.setBorder( new TitledBorder("Red Alignment") );
red.add( new JLabel("X Alignment:") );
redAlignmentX = createComboBox();
red.add( redAlignmentX );
red.add( new JLabel("Y Alignment:") );
redAlignmentY = createComboBox();
red.add( redAlignmentY );
panel.add( red );
JButton reset = new JButton("Reset Alignment");
reset.addActionListener( this );
panel.add( reset );
return panel;
}
public void actionPerformed(ActionEvent e)
{
green.setAlignmentX( ((Float)greenAlignmentX.getSelectedItem()) );
green.setAlignmentY( ((Float)greenAlignmentY.getSelectedItem()) );
red.setAlignmentX( ((Float)redAlignmentX.getSelectedItem()) );
red.setAlignmentY( ((Float)redAlignmentY.getSelectedItem()) );
JPanel parent = (JPanel)green.getParent();
parent.revalidate();
/*
System.out.print(green.getAlignmentX() + " : ");
System.out.print(green.getAlignmentY() + " : ");
System.out.print(red.getAlignmentX() + " : ");
System.out.print(red.getAlignmentY() + " : ");
System.out.println();
*/
SwingUtilities.invokeLater(new Runnable()
{
public void run()
{
greenLabel.setText( green.getLocation().toString() );
redLabel.setText( red.getLocation().toString() );
}
});
}
private JComboBox createComboBox()
{
JComboBox<Float> comboBox = new JComboBox<Float>();
comboBox.addItem( new Float(0f) );
comboBox.addItem( new Float(0.25f) );
comboBox.addItem( new Float(0.5f) );
comboBox.addItem( new Float(0.75f) );
comboBox.addItem( new Float(1.0f) );
comboBox.setSelectedItem(0.5f);
return comboBox;
}
private static void createAndShowUI()
{
JFrame frame = new JFrame("OverlayLayoutTest");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add( new OverlayLayoutTest() );
frame.pack();
frame.setLocationByPlatform( true );
frame.setVisible( true );
}
public static void main(String[] args)
{
EventQueue.invokeLater(new Runnable()
{
public void run()
{
createAndShowUI();
}
});
}
}
set the alignment X values to 1.0 for both components
set the alignment Y values to 0.0 for both components
and you should get the layout you want.
Edit:
Missed the part about dragging a JInternalFrame. So this imples you are using a JDesktopPane to support the dragging. A JDesktopPane uses a null layout to allow you to drag components around.
There is no reason you can't add another component (other than a JInternalFrame) to the desktop. You just need to set the size/location of this component to be displayed at the top right of the desktop. You would then need to add a ComponentListener to the desktop pane to listen for the componentResized event. When this event is fired you would need to recalucate the location of the component to reset it to the top right.

JScrollPane not showing the scroll bars inside a JSplitPane

I have this piece of code that is basically a JFrame that contains a JSplitPane which contains on the left side a JScrollPane which contains a JPanel. I expected to see the scroll bars since the JPanel inside the JScrollPane is larger that the JScrollPane itself. Why are the scroll bars not displayed?
If I replace setSize() with setPreferredSize() then it works, but I want to use setSize(). Is there any way I can use setSize() and have the scroll bars showing?
import java.awt.*;
import javax.swing.*;
public class Test {
public static void main( String[] args ) {
JFrame frame = new JFrame();
frame.setLayout( new BorderLayout() );
JSplitPane splitPane = new JSplitPane();
frame.add( splitPane, BorderLayout.CENTER );
JPanel panel = new JPanel();
panel.setBackground( Color.red );
panel.setSize( 1920, 1200 );
//panel.setPreferredSize( new Dimension( 1920, 1200 ) );
JScrollPane scrollPane = new JScrollPane( panel );
splitPane.setLeftComponent( scrollPane );
splitPane.setRightComponent( new JPanel() );
frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
frame.pack();
frame.setVisible( true );
frame.setSize( 960, 600 );
}
}
Edit: I've added a modified version where I use setPreferredSize(). Is there a better solution for dynamically changing the size?
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Test {
public static void main( String[] args ) {
JFrame frame = new JFrame();
frame.setLayout( new BorderLayout() );
JSplitPane splitPane = new JSplitPane();
frame.add( splitPane, BorderLayout.CENTER );
final JPanel panel = new JPanel();
panel.setBackground( Color.red );
panel.setPreferredSize( new Dimension( 1920, 1200 ) );
JScrollPane scrollPane = new JScrollPane( panel );
splitPane.setLeftComponent( scrollPane );
JButton button = new JButton();
button.addActionListener( new ActionListener() {
#Override
public void actionPerformed( ActionEvent e ) {
panel.setPreferredSize( new Dimension( 3840, 2400 ) );
panel.revalidate();
}
});
splitPane.setRightComponent( button );
frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
frame.pack();
frame.setVisible( true );
frame.setSize( 960, 600 );
}
}

Your setSize will be ignored by the JSplitPane because the layout of the left/right components is not null, and it tries to fit the internal components in the available space.
The layout manager for the JSplitPane's left/right components honors the preferredSize property(and not the size property) and if it hasn't been set, it just tries to fit the internal component inside the available space of left/right area in JSplitPane.
Use setPreferredSize instead or override the getPreferredSize method for your panel as camickr described in the comment.

Miglayout, baseline and JTextAreas

I am using MigLayout (and I really like it). But I have a problem with Labels in front of a JTextArea.
I have read about the "baseline" keyword. But that does not work in combination with "grow".
Here is an example that shows the problem.
I expected the label to be aligned at the top (at the same location as the first line of the JTextArea).
Any ideas?
public class MigRunner {
public static void main( String[] args ) {
SwingUtilities.invokeLater( new Runnable() {
#Override
public void run() {
new MigRunner().run();
}
} );
}
#UiThread
private void run() {
JFrame frame = new JFrame();
Container contentPane = frame.getContentPane();
contentPane.setLayout( new MigLayout("wrap 2, fill, debug", "[][grow]", "[grow]") );
{
JLabel name = new JLabel( "Description" );
contentPane.add( name, "baseline" );
JTextArea textArea = new JTextArea();
JScrollPane scrollPane = new JScrollPane( textArea );
contentPane.add( scrollPane, "grow, baseline" );
name.setLabelFor( textArea );
}
frame.setDefaultCloseOperation( WindowConstants.DISPOSE_ON_CLOSE );
frame.setSize( 400, 300 );
frame.setLocationRelativeTo( null );
frame.setVisible( true );
}
}

Maybe you need the align contraint:
JLabel name = new JLabel("Description");
contentPane.add(name, "aligny top");
I didn't saw the 3 pixel gap between the baselines of the texts until Jeremias' comment. Well I don't have a nice solution for this, but here is an additional idea to Jeremias "gaptop 3" solution:
JTextArea name = new JTextArea("Description");
name.setEditable(false);
contentPane.add(new JScrollPane(name), "aligny top");

Using two JPanels in one JFrame

I'm attempting to create a program that allows the user to click a button to place something in the JPanel and allowing them to move this item around. I have already found a good layout to use to allow the moving components (see this link). However, I'm just curious the best way to create a layout like this? My hope is to have something like this:
How can I accomplish this? Would I want to use two JPanel's or something else?

The main panel (or the window content pane) would have to have a BorderLayout as the layout manager.
Then, the buttons panel would be added to BorderLayout.WEST and the drag panel to BorderLayout.CENTER.
There is a Visual Guide to swing layout managers.

Try to use JSplitPane:
Here is a code example:
class SplitPane extends JFrame {
private JSplitPane splitPaneV;
private JSplitPane splitPaneH;
private JPanel panel1;
private JPanel panel2;
private JPanel panel3;
public SplitPane(){
setTitle( "Split Pane Application" );
setBackground( Color.gray );
JPanel topPanel = new JPanel();
topPanel.setLayout( new BorderLayout() );
getContentPane().add( topPanel );
// Create the panels
createPanel1();
createPanel2();
createPanel3();
// Create a splitter pane
splitPaneV = new JSplitPane( JSplitPane.VERTICAL_SPLIT );
topPanel.add( splitPaneV, BorderLayout.CENTER );
splitPaneH = new JSplitPane( JSplitPane.HORIZONTAL_SPLIT );
splitPaneH.setLeftComponent( panel1 );
splitPaneH.setRightComponent( panel2 );
splitPaneV.setLeftComponent( splitPaneH );
splitPaneV.setRightComponent( panel3 );
}
public void createPanel1(){
panel1 = new JPanel();
panel1.setLayout( new BorderLayout() );
// Add some buttons
panel1.add( new JButton( "North" ), BorderLayout.NORTH );
panel1.add( new JButton( "South" ), BorderLayout.SOUTH );
panel1.add( new JButton( "East" ), BorderLayout.EAST );
panel1.add( new JButton( "West" ), BorderLayout.WEST );
panel1.add( new JButton( "Center" ), BorderLayout.CENTER );
}
public void createPanel2(){
panel2 = new JPanel();
panel2.setLayout( new FlowLayout() );
panel2.add( new JButton( "Button 1" ) );
panel2.add( new JButton( "Button 2" ) );
panel2.add( new JButton( "Button 3" ) );
}
public void createPanel3(){
panel3 = new JPanel();
panel3.setLayout( new BorderLayout() );
panel3.setPreferredSize( new Dimension( 400, 100 ) );
panel3.setMinimumSize( new Dimension( 100, 50 ) );
panel3.add( new JLabel( "Notes:" ), BorderLayout.NORTH );
panel3.add( new JTextArea(), BorderLayout.CENTER );
}
public static void main( String args[] ){
try {
UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
} catch (Exception evt) {}
// Create an instance of the test application
SplitPane mainFrame = new SplitPane();
mainFrame.pack();
mainFrame.setVisible( true );
}
}
You can play with splitPaneH.setOneTouchExpandable true/false
You can confugure divider location for both like:
Toolkit tk = Toolkit.getDefaultToolkit();
Dimension d = tk.getScreenSize();
int width = d.width;
int height = d.height;
spane.setDividerLocation((width*3)/4);
spanex.setDividerLocation(width/4);

how to build a custom JTable in Java, with a row above the column names

I am using AbstractTableModel to create a simple custom table,as usual with a String[] for the column names and Object[][] for the contents in the JTable's rows .But, I found it hard to create a table containing an additional row (of one big cell spanning all columns for a general title) before the column names. Does anyone have any idea?

by using BorderLayout you can place TableHeader to the bottom of the Container
add(table, BorderLayout.CENTER);
add(header, BorderLayout.SOUTH);

It depends what you want your general title to look like.
You can easily add a JLabel above the table in a separate panel. Something like:
JPanel tablePanel = new JPanel( new BorderLayout() );
JLabel label = new JLabel( "Table Title" );
label.setHorizontalAlignment( JLabel.CENTER );
tablePanel.add(label, BorderLayout.NORTH);
JTable table = new JTable(...);
JScrollPane scrollPane = new JScrollPane( table );
tablePanel.add(scrollPane, BorderLayout.CENTER);
If you want the title to actually be a part of the column header then it is a little trickier. One way to do this is something like:
JTable table = new JTable(...)
{
#Override
protected void configureEnclosingScrollPane()
{
super.configureEnclosingScrollPane();
Container parent = getParent();
if (parent instanceof JViewport)
{
parent = parent.getParent();
if (parent instanceof JScrollPane)
{
JScrollPane scrollPane = (JScrollPane)parent;
JPanel columnHeader = new JPanel( new BorderLayout() );
JLabel label = new JLabel( "Table Title" );
label.setHorizontalAlignment( JLabel.CENTER );
columnHeader.add(label, BorderLayout.NORTH);
columnHeader.add(getTableHeader(), BorderLayout.CENTER);
scrollPane.setColumnHeaderView( columnHeader );
}
}
}
};
JScrollPane scrollPane = new JScrollPane( table );
add( scrollPane );