Develop Reference

How can I force 4 cells per row with equal width in Miglayout when only one cell is used?

I got a panel with a dynamic width. Components added to the panel should be arranged left-to-right up to 4 components (cells) per row, where each component/cell fill 25% of the panels width. If there is only one component, it should fill 25% of the parents width - the remaining 75% (3 cells) of the space should be empty.
I got it to work using a hack, but I'm not happy about that implementation - using cells and creating an "empty" panel for each cell that is not used. See the code snippet below:
MigLayout migLayout = new MigLayout("fillx, insets 0, wrap 4", "", "");
JPanel panel = new JPanel(migLayout);
JLabel label1 = new JLabel("1");
JLabel label2 = new JLabel("2");
JPanel filler1 = new JPanel();
JPanel filler2 = new JPanel();
panel.add(label1, "cell 0 0);
panel.add(label2, "cell 1 0);
panel.add(filler1, "cell 2 0);
panel.add(filler2 , "cell 3 0);
This gives something that can be illustrated like below, where the outer bracket is the outer panel, and the two inner brackets are the labels:
[ [ 1 ] [ 2 ] ]
Instead of using fillers I was hoping that it could be set with constraints, something like this:
MigLayout migLayout = new MigLayout("always 4 cells, fillx", "[fill][fill][fill][fill]", "");
JPanel panel = new JPanel(migLayout);
JLabel label1 = new JLabel();
JLabel label2 = new JLabel();
panel.add(label1);
panel.add(label2);
I have tried various layout constraints and add component parameters, but they are typically formatted like this:
[ [ 1 ] [ 2 ] ]

I would go with a GridLayout. GridLayout will separate your panel into cells according the given rows/cols (check its constructor). Then each component will fit 100% (width and height) to the cell.
However: If you set the grid layout to 1 row and 4 columns (your case) and you add only 1 component, the layout will be adjusted like: 1row and 1 column, because it won't let empty space.
Trick/Solution: Add an empty component exactly the same way we add gap to a BoxLayout.
private static Component createSpace() {
return Box.createRigidArea(new Dimension(1, 1));
}
Disadvantage:
If you want to add a component to the panel after it is being shown, you must remove the spaces, so you would have either to store all empty components into a structure or do the following (I always prefer it):
gridLayoutPanel.removeAll();
gridLayoutPanel.add(component1);
gridLayoutPanel.add(newComponent); //This was space before
gridLayoutPanel.add(createSpace());
gridLayoutPanel.add(createSpace());
gridLayoutPanel.repaint();
gridLayoutPanel.revalidate();
An SSCCE would be (ignore the height of the components):
import java.awt.Component;
import java.awt.Dimension;
import java.awt.GridLayout;
import javax.swing.Box;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.SwingUtilities;
public class GridLayoutTest extends JFrame {
public GridLayoutTest() {
getContentPane().setLayout(new GridLayout(1, 4));
JButton component1 = new JButton("Component1");
JButton component2 = new JButton("Component2");
JButton component3 = new JButton("Component3");
add(component1); //25% of the width
add(component2); //25% of the width
add(component3); //25% of the width
add(createSpace()); //25% of the width
setDefaultCloseOperation(EXIT_ON_CLOSE);
setSize(500, 200);
setLocationRelativeTo(null);
}
private static Component createSpace() {
return Box.createRigidArea(new Dimension(1, 1));
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> new GridLayoutTest().setVisible(true));
}
}

You can use % in the column constraint, and remember to add the '!' so that each column has a fix width.
MigLayout migLayout = new MigLayout("wrap 4, fill", "[25%!,fill][25%!,fill][25%!,fill][25%!,fill]");
JPanel panel = new JPanel(migLayout);
JLabel label1 = new JLabel();
JLabel label2 = new JLabel();
panel.add(label1, "grow"); // add grow here if you want to fill up the 25%
panel.add(label2, "grow");
also check out http://www.miglayout.com/whitepaper.html, all the miglayout tricks are in it

Probably a bit late, but I think this the solution:
public class Test extends JFrame {
public Test() {
// Col Constraint
String ccol="[fill, 25%:25%:25%]";
// Cell Constraint
String ccell="";
MigLayout migLayout = new MigLayout("debug, fillx, insets 5, wrap 4", ccol+ccol+ccol+ccol, "");
Container panel = getContentPane();
panel.setLayout(migLayout);
MyComponent label;
// row 1
label = new MyComponent("1.1");
panel.add(label, ccell + "cell 0 0");
label = new MyComponent("1.2");
panel.add(label, ccell + "cell 1 0");
// row 2
label = new MyComponent("2.1");
panel.add(label, ccell + "cell 0 1");
setDefaultCloseOperation(EXIT_ON_CLOSE);
setSize(500, 200);
setLocationRelativeTo(null);
}
/**
* #param args the command line arguments
*/
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> new Test().setVisible(true));
}
private static class MyComponent extends JLabel {
public MyComponent(String text) {
super(text);
setOpaque(true);
setBackground(Color.YELLOW);
}
}
}

MigLayout: How to *vertically* align multiple components inside a dock?

MigLayout supports adding multiple components to a dock. I want to add multiple components to the west dock, from top to bottom. However, it seems as if MigLayout can only manage a horizontal layout inside a dock. I tried many parameters (e.g., wrap, growy, flowy) without success.
So, is there any possibility to wrap or set a vertical flow inside a dock? Or is this not possible with MigLayout itself, but only by using an extra sidepanel-component?
Here an example of the unwanted horizontal layout inside the west dock:
How to get the red, green, blue components below each other? Here is the code:
import java.awt.Color;
import javax.swing.JFrame;
import javax.swing.JTextField;
import net.miginfocom.swing.MigLayout;
public class MigTest extends JFrame {
MigTest() {
setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
setSize(800, 600);
setLayout(new MigLayout("fill"));
JTextField dockW1 = new JTextField("West 1"); dockW1.setBackground(Color.red);
JTextField dockW2 = new JTextField("West 2"); dockW2.setBackground(Color.green);
JTextField dockW3 = new JTextField("West 3"); dockW3.setBackground(Color.blue);
JTextField center = new JTextField("Center"); center.setBackground(Color.lightGray);
add(center, "grow");
// HOW TO LAYOUT THESE COMPONENTS VERTICALLY INSIDE WEST DOCK ?
add(dockW1, "dock west, wrap, growy, flowy");
add(dockW2, "dock west, wrap, growy, flowy");
add(dockW3, "dock west, wrap, growy, flowy");
setVisible(true);
}
public static void main(String[] args) {
new MigTest();
}
}
[edit]: Note that I do not want to put dockW1, dockW2,dockW3, and center into a single grid, since I plan to apply a complex layout in the center area, independently of the side-area, which is the reason why the docking feature was invented :)

My first suggestion is to change the constructor of the MigLayout to
new MigLayout("fill","[][grow]","[][][]")
Then change your add statement to :
add(center, "cell 1 0 1 3, grow");
add(dockW1, "cell 0 0");
add(dockW2, "cell 0 1");
add(dockW3, "cell 0 2");
Edit
After you edited the question, I would suggest you to create a new JPanel object say dockWest and add the components dockW1, dockW2 and dockW3 to dockWest and finally dock the dockWest to the west of the current JFrame like:
JPanel dockWest = new JPanel();
dockWest.setLayout(new MigLayout("fill", "[]", "[grow][grow][grow]");
dockWest.add(dockW1, "cell 0 0");
dockWest.add(dockW2, "cell 0 1");
dockWest.add(dockW3, "cell 0 2");
add(dockWest, "dock west, growy");

IMHO the side-panel is easier option with the same result.
You can also try using cell coordinates as written on page 2 in Quick guide.

Centering labels with MigLayout

I'm trying to center labels using MigLayout and I'm having a difficult time. Here's what I'd like the labels to look like:
| [label1] [label2] [label3] [label4] [label5] |
| ............ [label6][label7][label8] ............| |
I'd like to:
Limit the number of labels to five per row and I think I can use wrap 5.
Center the labels inside the JPanels
I have labeled sections on the main JPanel with subpanels, like this:
Section 1
[subpanel with labels]
Section 2
[subpanel with labels]
There's no problem with centering if there's only a single label because I do this:
myPanel.add(label, "align center, wrap");
Unfortunately, if I add more than one they just don't center. I've gone through the MigLayout Cheat Sheet but it's like going through an API without fully understanding how it all works and I haven't been able to find any good tutorials out there. I'd like to become proficient with MigLayout, so a good tutorial would probably do the trick.
I'd be grateful for your help.

I am not exactly sure what you want but this is my guess:
panel.add(label1);
panel.add(label2);
panel.add(label3);
panel.add(label4);
panel.add(label5, "wrap");
panel.add(label6, "al 100%");
panel.add(label7, "align center");
panel.add(label8);
frame.pack();

you can make miglayout with center column constraint and you can add it by cell no.
JPanel panel = new JPanel(new MigLayout("","[center][center][center][center][center]","[]"));
JLabel label1 = new JLabel("label1");
JLabel label2 = new JLabel("label2");
JLabel label3 = new JLabel("label3");
JLabel label4 = new JLabel("label4");
JLabel label5 = new JLabel("label5");
panel.add(label1, "cell 0 0");
panel.add(label2, "cell 1 0");
panel.add(label3, "cell 2 0");
panel.add(label4, "cell 3 0");
panel.add(label5, "cell 4 0");
f.getContentPane().add(panel);

I'm trying to set JTextField under JLabel

I'm trying to put the text field under the JLabel. Currently, the text field is displayed on the same line. It should be below and centered. I need assistance.
package Gui;
import javax.swing.*;
import java.awt.*;
import java.awt.GridLayout;
public class ShowGridLayout extends JFrame {
public ShowGridLayout() {
// Set GridLayout, 3 rows, 2 columns, and gaps 5 between
// components horizontally and vertically
setLayout(new GridLayout(3, 2, 5, 5));
// Add labels and text fields to the frame
JLabel firstname = new JLabel("First Name");
add(firstname);
JTextField fistnametextField = new JTextField(8);
add(fistnametextField);
JLabel mi = new JLabel("Mi");
add(mi);
JTextField miTextField = new JTextField(1);
add(miTextField);
JLabel lastname = new JLabel("Last Name");
add(lastname);
JTextField lastnameTextField = new JTextField(8);
add(lastnameTextField);
}
/**
* Main method
*/
public static void main(String[] args) {
ShowGridLayout frame = new ShowGridLayout();
frame.setTitle("ShowGridLayout");
frame.setSize(200, 125);
frame.setLocationRelativeTo(null); // Center the frame
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
}

You could simply use a GridLayout with a single column:
setLayout(new GridLayout(0, 1));
Note that GridLayout will ignore the preferred sizes of the JTextFields so using the constructor JTextField(int columnSize) will have no effect so the default constructor will do.
Also I would remove the internal spacing here and add a border to the JFrame:
(JComponent)getContentPane()).setBorder(
BorderFactory.createEmptyBorder(10, 10, 10, 10) );
This would produce a frame that looks like

You are creating a 3x2 grid. That is, 3 rows of 2 columns each. the first call to add() will put the component in row 1, col 1 and the second call will put the component in row 1 col 2. So they are next to each other. With GridLayout you do not have much control over this. If you want items to be one over the next you can try a 3x1 grid. Or you can try adding components in a different order. Or you can try a different layout manager such as GridBagLayout where you have more control.

Question about making a JAVA GUI of a certain format

I am trying to make a GUI that looks something like this:
I only know how to use the BorderLayout which has space for 5 buttons. North, West, Center, East, and South.
Since I need to have 6 components on the top line, this approach can't work. I'm not sure how to make it so that I can have more than 1 component on the top line. Are there other layouts that I can use or is there some way I can manipulate BorderLayout so that I can put 6 components on the top line?

What you need to do is nest components inside of other components. For example, the top (North) should be one JPanel. That JPanel will contain the 6 components on the top.
The code may look similar to the following:
JPanel northPane = new JPanel();
northPane.add(new JLabel("Principle: "));
northPane.add(principleTextBox);
... and so on
mainPanel.setLayout(new BorderLayout());
mainPanel.add(northPanel, BorderLayout.NORTH);
The Center component will probably be another JPanel containing the two center buttons. And the South component will be another JPanel containing the single JLabel or simply the JLabel.
If you don't have to use a BorderLayout for the main panel, it may be easier to use a BoxLayout.

Once again I turn to miglayout, the absolute best layout manager for Java. No nested JPanels, just a simple layout using string based constraints.
With debug mode on:
After resizing the window (note the ratio of the size of the textfields remains the same)
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import net.miginfocom.swing.MigLayout;
/**
*
* #author nicholasdunn
*/
public class InterestCalculator extends JPanel {
public InterestCalculator() {
super(new MigLayout("debug, fill", "align center"));
// Make 6 components cram into one cell
add(new JLabel("Principal:"), "split 6");
// This textfield grows at twice the normal rate
add(new JTextField(), "growx 200");
add(new JLabel("Interest rate (percentage):"));
// This one at a normal rate
add(new JTextField(), "growx 100");
add(new JLabel("Years:"));
// This one at half the normal rate
add(new JTextField(), "growx 50, wrap");
// The row with the two buttons
add(new JButton("Compute simple interest"), "split 2");
add(new JButton("Compute compound interest"), "wrap");
// The result label
add(new JLabel("The result with simple interest would be"));
}
public static void main(String[] args) {
JFrame frame = new JFrame("");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel panel = new InterestCalculator();
frame.add(panel);
frame.pack();
frame.setVisible(true);
}
}

If I were recreating that UI, I would start with a JPanel using a GridLayout with 3 rows and 1 column. In each column I would add a child JPanel.
Then for each row I would use a GridBagLayout to position the components.

Here is a tutorial about layout managers.
Remember that you can always add several elements to a JPanel and apply a specific layout to that JPanel. Then you can nest panels(add panels inside other panels).