Develop Reference

Can I use multiple grids?

I am trying to figure out the layout for this(the rest of the code is in the early stages) but for this block, I am trying to figure out the best(and doable) way to format it. I want it to be an 8x8 grid that I will eventually populate with the treasure/empty buttons but I also need a title up top as well as some labels and text on the left. I am unsure if I am able to do multiple grids but what I did below is try to create a 1x2 grid and then place two other grids inside, one with the info on the left(3x2), and another with the 8x8 grid for the buttons. I know it's not close to what it needs to be but none of the grids are showing up at all(it's just putting the title and then one column with 8 rows) and I wanna know if I'm even on any sort of right track, or if I'm just making things up at this point. Any tips would be appreciated, or resources about possibly nesting the grids? I can't find anything in my book about That specifically.
private void buildPanel()
{
// Create labels to display the
treasuresLeftLabel = new JLabel("Treasures left: ");
treasuresFoundLabel = new JLabel("Treasures found: ");
triesLeftLabel = new JLabel("Tries left: ");
// Create text fields for each label
treasuresLeftTextField = new JTextField(2);
treasuresLeftTextField.setEditable(false);
treasuresLeftTextField.setText(String.valueOf(20-game.getTreasuresFound()));
treasuresFoundTextField = new JTextField(2);
treasuresFoundTextField.setEditable(false);
treasuresFoundTextField.setText(String.valueOf(game.getTreasuresFound()));
triesLeftTextField = new JTextField(2);
triesLeftTextField.setEditable(false);
triesLeftTextField.setText(String.valueOf(game.getTriesLeft()));
emptyButton = new EmptyButton();
emptyButton.addActionListener(new emptyButtonListener());
treasureButton = new TreasureButton();
treasureButton.addActionListener(new treasureButtonListener());
// new JPanel object referenced by panel
panel = new JPanel();
panel.setBorder(BorderFactory.createTitledBorder("Treasure Hunt"));
// Add a gridlayout to the content pane
panel.setLayout(new GridLayout(1, 2));
panel.setLayout(new GridLayout(3, 2));
panel.add(treasuresLeftLabel);
panel.add(treasuresLeftTextField);
panel.add(treasuresFoundLabel);
panel.add(treasuresFoundTextField);
panel.add(triesLeftLabel);
panel.add(triesLeftTextField);
panel.setLayout(new GridLayout(8, 8));
panel.add(treasureButton);
panel.add(emptyButton);
}

You can't use multiple grids within the same JPanel - one panel, one layout manager.
But you can nest layout managers (and thereby grids) by using nested panels.
For example you could use a BorderLayout for the first panel (containing the title at the top, the info panel on the left and the button panel in the center.
The code to construct those panel then might look like this:
// panel contains the complete UI
panel = new JPanel();
panel.setBorder(BorderFactory.createTitledBorder("Treasure Hunt"));
panel.setLayout(new BorderLayout());
panel.add(new JLabel("This is the Title"), BorderLayout.PAGE_START);
JPanel infoPanel = new JPanel();
infoPanel.setLayout(new GridLayout(3, 2));
infoPanel.add(treasuresLeftLabel);
infoPanel.add(treasuresLeftTextField);
infoPanel.add(treasuresFoundLabel);
infoPanel.add(treasuresFoundTextField);
infoPanel.add(triesLeftLabel);
infoPanel.add(triesLeftTextField);
panel.add(infoPanel, BorderLayout.LINE_START);
JPanel buttonPanel = new JPanel();
buttonPanel.setLayout(new GridLayout(8, 8));
buttonPanel.add(treasureButton);
buttonPanel.add(emptyButton);
for (int i = 0; i < 62; i++) {
buttonPanel.add(new JButton(String.format("%02d", i)));
}
panel.add(buttonPanel, BorderLayout.CENTER);

JPanel on top of another JPanel

I have been using JPanels for a while and now want to place a JPanel on top of another JPanel.
I have looked at using JLayer but I was wondering If there is a solution to just set the layer of the bottom and top, I don't want to set each components layer if possible.
Example
JPanel bottomPanel = new JPanel(); # Set as bottom panel
JPanel topPanel = new JPanel(); # Set as top panel
JPanel sidePanel = new JPanel(); # Don't have to set
JPanel anotherSidePanel = new JPanel(); # Don't have to set
If this isn't possible what is the best solution for this, Thanks.

You can have the main panel use a BorderLayout.
Then you can do something like:
mainPanel.add(leftSide, BorderLayout.LINE_START);
mainPanel.add(rightSide, BorderLayout.LINE_END);
JLayeredPane lp = new JLayeredPane();
mainPanel.add(lp, BorderLayout.CENTER);

It sounds like what you want is a layout manager. There are a few different ones that suit different needs. There's a link at the bottom of this post.
My personal favorite is GridLayout. So for what you want to do, you can do this:
JPanel panel = new JPanel();
panel.setLayout(new GridLayout(2, 1));
//the first number is the number of rows, the second is the number of columns
JPanel topPanel = new JPanel();
JPanel bottomPanel = new JPanel();
panel.add(topPanel);
panel.add(bottomPanel);
That will do what you want.
If you wanted to read more about them, here's a link:
Oracle Docs on Layout Managers

I know this is quite late, but if anyone now has this issue, I suggest using a BoxLayout. BorderLayout can only have one cell in each of its five locations, and GridLayout's cells are all the same dimension. If you want to stack different sized JPanels, here's how BoxLayout can be implemented:
JFrame frame = new JFrame("Intro to BoxLayout");
JPanel container = new JPanel();
JPanel panel1 = new JPanel();
panel1.setPreferredSize(new Dimension(X1, Y1));
JPanel panel2 = new JPanel();
panel2.setPreferredSize(new Dimension(X2, Y2));
container.setLayout(new BoxLayout(container, BoxLayout.PAGE_AXIS));
container.add(panel1);
container.add(panel2);
frame.add(container);
frame.pack();
frame.setVisible(true);
where X1, Y1, X2, Y2 are arbitrary panel dimensions.

How do I keep JTextFields in a Java Swing BoxLayout from expanding?

I have a JPanel that looks something like this:
JPanel panel = new JPanel();
panel.setLayout(new BoxLayout(panel, BoxLayout.Y_AXIS));
...
panel.add(jTextField1);
panel.add(Box.createVerticalStrut(10));
panel.add(jButton1);
panel.add(Box.createVerticalStrut(30));
panel.add(jTextField2);
panel.add(Box.createVerticalStrut(10));
panel.add(jButton2);
... //etc.
My problem is that the JTextFields become huge vertically. I want them to only be high enough for a single line, since that is all that the user can type in them. The buttons are fine (they don't expand vertically).
Is there any way to keep the JTextFields from expanding? I'm pretty new to Swing, so let me know if I'm doing everything horribly wrong.

textField = new JTextField( ... );
textField.setMaximumSize( textField.getPreferredSize() );

If you want the width to keep changing, just keep it set to MAX INT. So...
textField.setMaximumSize(
new Dimension(Integer.MAX_VALUE, textField.getPreferredSize().height) );

In my case I need a combination of all the answers for it to work properly. If I don't use glue, it is not centered vertically; if I don't restrict maximum size, it extends vertically; if I restrict both width and height, it is too small, being only wide enough to contain the initialization text.
textField = new JTextField("Hello, world!");
textField.setMaximumSize(
new Dimension(Integer.MAX_VALUE,
textField.getPreferredSize().height));
Box box = Box.createVerticalBox();
box.add(Box.createVerticalGlue());
box.add(textField);
box.add(Box.createVerticalGlue());

set the max height.
or put them in a scroll region

JPanel panel = new JPanel();
Box box = Box.createVerticalBox();
JTextField tf = new JTextField(8);
box.add(tf);
panel.add(box);
frame.getContentPane().add(panel, BorderLayout.CENTER);

How do i get vertical scrolling to JPanel?

I have written a code in java using swing, so that I will have a JscrollPane added to JPanel and then I will add buttons of fixed size to JPanel in vertical fashion
JPanel panel=new JPanel();
panel.setBackground(Color.WHITE);
int v=ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS;
int h=ScrollPaneConstants.HORIZONTAL_SCROLLBAR_ALWAYS;
JScrollPane jsp=new JScrollPane(panel,v,h);
jsp.setPreferredSize(new Dimension(600,600));
jsp.setBounds(150,670,850,200);
frame.add(jsp);
then I am adding buttons to it at run time.
for(i=0;i<n;i++)
{
button[i]=new JButton();
button[i].setBounds(20,y,120,120);
button[i].setSize(120,120);
button[i].setToolTipText(file[i].toString());
button[i].setIcon(Icon);
panel.add(button[i]);
y=y+140;
}
I want to add a buttons one below the other...(i.e I want a vertical scrollbar)
i.e. button1
button2
'
'
but above code is giving me buttons in a line (i.e. I am getting horizontal scrollbar)
i.e. button1 button2...
another problem is the size of the buttons. Using btn.setSize() is not affecting size at all...
can anybody help me?

You must use an appropriate Layoutmanager like GridLayout, Boxlayout or GridBagLayout for the panel.
It depends what else you want to put into the panel.
GridLayout is easier to use IMO:
JPanel panel = new JPanel();
panel.setLayout(new GridLayout(0, 1)); // any number of rows, 1 column
...
panel.add(button[i]);
BoxLayout is almost as easy:
JPanel panel = new JPanel();
panel.setLayout(new BoxLayout(panel, BoxLayout.Y_AXIS));
...
panel.add(button[i]);
GridBagLayout is more powerful, allowing more than one column, components spanning more than one cell, ... needs a GridBagConstraints to add the elements:
JPanel panel = new JPanel();
panel.setLayout(new GridBagLayout());
GridBagConstraints constraints = new GridBagConstraints(
0, RELATIVE, // x = 0, y = below previous element
1, 1, // cell width = 1, cell height = 1
0.0, 0.0 // how to distribute space: weightx = 0.0, weighty = 0,0
GridBagConstraints.CENTER, // anchor
GridBagConstraints.BOTH, // fill
new Insets(0, 0, 0, 0), // cell insets
0, 0); // internal padding
...
panel.add(button[i], constraints);
Have a look at this tutorial: Laying Out Components Within a Container (The visual guide is a good start point)
EDIT:
you can also lay out the components by hand, that is, specify the location and size of each component in the container. For this you must set the LayoutManager to null so the default manager gets removed.
JPanel panel = new JPanel();
panel.setLayout(null);
...
button[i].setLocation(x, y);
button[i].setSize(width, heigth);
// OR button[i].setBounds(x, y, width, height);
panel.add(button[i]);

You need to define an appropriate LayoutManager for your JPanel, which is responsible for how the Components added to it are positioned. The default LayoutManager is FlowLayout, which lays out Components left-to-right. For laying out Components vertically you should consider using BoxLayout or GridBagLayout.

You have to set LayoutManager for JPanel or use Box(BoxLayout.Y_AXIS) instead.

For the size of buttons use preferredSize
For your layout problem you need to change the layout manager to one that does a vertical layout. For playing around purposes you can use BoxLayout like this:
panel.setLayout(new BoxLayout(panel, BoxLayout.Y_AXIS));

This is much easier if you let the layout manager do its work.
In Swing, the way the components are layout over other component ( a panel for instance ) is using a layout manager.
It is used to avoid having to compute the coordinates of all the components against each other each time the container component resizes, or a new component is added.
There are different layout mangers, the one that you need here is BoxLayout.
By using this layout you don't need to specify the button position, nor its size. The layout manager query each component and use that information to place them in the correct position and size.
For instance the following frame
Was created this ( modified version of your ) code:
import javax.swing.*;
import java.awt.*;
public class ScrollTest {
private JPanel panel;
private Icon[] icons = new Icon[3];
public void main() {
panel =new JPanel();
// Use top to bottom layout in a column
panel.setLayout( new BoxLayout( panel, BoxLayout.Y_AXIS ));
panel.setBackground(Color.WHITE);
int v=ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS;
int h=ScrollPaneConstants.HORIZONTAL_SCROLLBAR_ALWAYS;
JScrollPane jsp=new JScrollPane(panel,v,h);
jsp.setPreferredSize(new Dimension(600,600));
jsp.setBounds(150,670,850,200);
JFrame frame = new JFrame();
frame.add(jsp);
// my addition to load sample icons
loadImages();
// simulate dynamic buttons
addButtons();
frame.pack();
frame.setVisible( true );
}
void loadImages() {
icons[0] = new ImageIcon( "a.png" );
icons[1] = new ImageIcon( "b.png" );
icons[2] = new ImageIcon( "c.png" );
}
void addButtons() {
for( int i = 0 ; i < icons.length ; i++ ) {
JButton button = new JButton();
Icon icon = icons[i];
button.setIcon( icon );
// Set the button size to be the same as the icon size
// The preferred size is used by the layout manager
// to know what the component "better" size is.
button.setPreferredSize( new Dimension( icon.getIconWidth(),
icon.getIconHeight() ) );
// This is IMPORTANT. The maximum size is used bythe layout manager
// to know "how big" could this component be.
button.setMaximumSize( button.getPreferredSize() );
panel.add( button );
}
}
public static void main( String ... args ) {
new ScrollTest().main();
}
}
I hope this helps.

One can also get a vertical scrolling for JPanel with SpringLayout. It's possible if panel's vertical size will be defined by setting a constraint SpringLayout.SOUTH. This can be done like this:
JPanel panel = new JPanel();
SpringLayout panelLayout = new SpringLayout();
panel.setLayout(panelLayout);
// Adding components to the panel here
// .....
// That's what defines panel's exact size and makes its scrolling possible
panelLayout.putConstraint(SpringLayout.SOUTH, panel, 0,
SpringLayout.SOUTH, lastComponentOfThePanel);
JScrollPane panelScrollPane = new JScrollPane(panel);
where lastComponentOfThePanel is a component at the bottom of a panel.
Hope this will help somebody. In my opinion, SpringLayout is very powerful layout manager, and sometimes it's very difficult or almost impossible to replace this one with GridBagLayout.

What about?
JScrollPane scrollPane = new JScrollPane(yourpanel);
container.add(scrollPane);

How can I set a JPanel maximum or preferred size that uses gridLayout?

I had problem using a very simple frame containing two JPanel.
The problem is on the layout of the Center JPanel that contains four JButton.
How can I set a better size for buttons or directly for JPanel that uses the GridLayout. On the picture the problem:
alt http://img42.imageshack.us/img42/4601/horrible.jpg
!
Here the code: ` JFrame window = new JFrame("Horrible! LOL");
JTextField textField = new JTextField("");
textField.setPreferredSize(new Dimension(200,20));
JPanel textPanel = new JPanel(new FlowLayout(FlowLayout.CENTER));
textPanel.add(textField);
window.add(textPanel, BorderLayout.NORTH);
JButton plus = new JButton("+");
//plus.setPreferredSize(new Dimension(50,50)); nothing would change
JButton minus = new JButton("-");
JButton per = new JButton("x");
JButton divide = new JButton("/");
JPanel prova = new JPanel(new GridLayout(2,2,10,10));
Dimension d = new Dimension(20,20);
prova.setMaximumSize(d); // nothing changed!
prova.add(plus);
prova.add(minus);
prova.add(per);
prova.add(divide);
window.add(prova, BorderLayout.CENTER);
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
window.setSize(250,300);
window.setResizable(false);
window.setVisible(true);`
Which is a good solution?
Kind regards

Unfortunately gridlayout doesent respect preferred sizes. But still if you want to stick to grid layout then you can try something like this:
public static JComponent wrap(JComponent comp)
{
JPanel panel = new JPanel();
panel.add(comp);
return panel;
}
And then instead of direclty adding in to prova add like this:
prova.add(wrap(plus));
prova.add(wrap(minus));
prova.add(wrap(per));
prova.add(wrap(divide));
Tested, Works perfect!!
There are other better ways though

That's what happen to me:
It's definitely attached to the upper edge of the grid.
alt text http://img96.imageshack.us/img96/9431/stillnot.jpg
Even if in this case, in the wrap method I can set the preferredSize of buttons/comp, every buttons is on its own edge. What about others solutions. How would you position buttons for a calculator?
Kind regards and thanx angain!