Develop Reference

GUI components not aligning vertically inside JPanel in Card layout

Image of my GUI.
I am trying to add components to two JPanel containers and then add those panels as cards. I want the checkboxes after labels in a vertical manner. The problem I am facing is that the components are coming in a grid of two columns:
public class MyFrame extends JFrame {
MyFrame(int width, int height, String title){
setTitle(title);
setSize(width, height);
JPanel internalJP1 = new JPanel(new GridLayout(5,1));
JLabel hobby = new JLabel("Enter your hobbies:");
JCheckBox cricket = new JCheckBox("Cricket");
JCheckBox music = new JCheckBox("Music");
JCheckBox drawing = new JCheckBox("Drawing");
JCheckBox dancing = new JCheckBox("Dancing");
JCheckBox other = new JCheckBox("Other");
internalJP1.add(hobby);
internalJP1.add(cricket);
internalJP1.add(music);
internalJP1.add(drawing);
internalJP1.add(dancing);
internalJP1.add(other);
JPanel internalJP2 = new JPanel(new GridLayout(4,1));
JLabel payment = new JLabel("Payment by:");
ButtonGroup buttonGroup = new ButtonGroup();
JRadioButton cheque = new JRadioButton("Cheque", false);
JRadioButton cash = new JRadioButton("Cash", false);
JRadioButton debitCard = new JRadioButton("Debit Card", false);
JRadioButton creditCard = new JRadioButton("Credit Card", false);
buttonGroup.add(cheque);
buttonGroup.add(cash);
buttonGroup.add(debitCard);
buttonGroup.add(creditCard);
internalJP2.add(payment);
internalJP2.add(cheque);
internalJP2.add(cash);
internalJP2.add(debitCard);
internalJP2.add(creditCard);
Container c = getContentPane();
CardLayout cl = new CardLayout();
c.setLayout(cl);
c.add(internalJP1,"crd1");
c.add(internalJP2,"crd2");
cl.show(c,"crd1");
}
}
public class Jtest {
public static void main(String[] args) {
MyFrame frame = new MyFrame(300,200,"FirstFrame");
frame.setVisible(true);
}
}

Just change this line of code (in constructor of class MyFrame)
JPanel internalJP1 = new JPanel(new GridLayout(5,1));
to this
JPanel internalJP1 = new JPanel(new GridLayout(0,1));
i.e. replace 5 with 0
I find GridLayout to not be intuitive. When the row parameter of GridLayout constructor is zero, then each row will contain exactly the number of columns indicated. Hence new GridLayout(0, 1) will ensure that each row (in the grid) will contain exactly one column and it will create as many rows as required in order to ensure this.
Note that GridLayout is not the only layout manager to use when you want to place GUI components in a single column. Swing also has BoxLayout, GridBagLayout, GroupLayout and SpringLayout.
There are also third party layout managers including JGoodies and MiG Layout.

The fact that you are using a CardLayout to view one panel or the other does not affect the layout of those panels. Your problem is entirely related to the layout of the 2 panels.
There are 2 easy ways to fix the panels to make them 1-column:
fix their number of rows so that it is >= the number of elements that you actually add. Now, you have JPanel internalJP1 = new JPanel(new GridLayout(5,1)); - but add 6 elements. If you change it to JPanel internalJP1 = new JPanel(new GridLayout(6,1));, you will solve the problem for your 1st panel. The same fix applies to your second panel. Even better, use 0 to make the layout use as many rows as it needs (see docs).
use a vertical BoxLayout and do not worry about the number of elements at all - just stack them vertically. This has the additional advantage that they look better, because even if you give the layout more size than it needs, they still stack together nicely: JPanel internalJP1 = new JPanel(); internalJP1.setLayout(new BoxLayout(internalJP1, BoxLayout.Y_AXIS));

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);
}
}
}

java swing calculator layouts

I need to do an assignment and create a calculator. It's a beginner Java course, so keep in mind that I'm no expert. It shouldn't look spectacular, so the easiest way to achieve the below would be great.
The inner workings of it is fine, but drawing it has been a real headache.
We've only gotten exposure to flowlayout so far...and in this instance it's not what I want at all. Let me start of by telling you what layout I'm looking for:
At the top a heading spreading across the calculator, with perhaps a
background fill.
Then below that, 2 buttons next to each other.
Below that, two labels next to each other.
Then two text field next to each other.
Below that, two labels next to each other.
Then two text field next to each other.
I tried drawing it here, but it doesn't format correctly. If I can put it in HTML it would basically be a simple table, with 6 rows and 2 columns. But the top row must span across both columns.
Flowlayout just put everything next to each other from left to right.
After that I tried using GridLayout, but the top heading was the problem here, as it didn't span across both columns.
Here is my code so far:
public class TripCalculator extends JFrame implements ActionListener {
public static final int WIDTH = 400;
public static final int HEIGHT = 300;
public static final int NUMBER_OF_CHAR = 4;
public JTextField stopTime, distance, tripTime, speed;
public TripCalculator() {
setSize(WIDTH, HEIGHT);
WindowDestroyer listener = new WindowDestroyer();
addWindowListener(listener);
Container contentPane = getContentPane();
contentPane.setLayout(new FlowLayout());
JLabel heading = new JLabel("HEADING");
contentPane.add(heading);
contentPane.setLayout(new FlowLayout());
JButton addStop = new JButton("BUTTON1");
addStop.addActionListener(this);
JButton addLeg = new JButton("BUTTON2");
addLeg.addActionListener(this);
contentPane.add(addStop);
contentPane.add(addLeg);
JLabel subHead1 = new JLabel("LABEL1");
contentPane.add(subHead1);
JLabel subHead2 = new JLabel("LABEL2");
contentPane.add(subHead2);
stopTime = new JTextField(NUMBER_OF_CHAR);
contentPane.add(stopTime);
distance = new JTextField(NUMBER_OF_CHAR);
contentPane.add(distance);
JLabel subHead3 = new JLabel("LABEL3");
contentPane.add(subHead3);
JLabel subHead4 = new JLabel("LABEL4");
contentPane.add(subHead4);
tripTime = new JTextField(NUMBER_OF_CHAR);
contentPane.add(tripTime);
speed = new JTextField(NUMBER_OF_CHAR);
contentPane.add(speed);
}
}
I would greatly appreciate if anyone can show me in the right direction.

Flowlayout or Gridlayout by themselves won't help you. Either you can use Gridbaglayout, or a combination of layouts such as FlowLaout+Gridlayout.
If you are drawing a calculator, I am assuming you are drawing something like this :
Where you have title information at the top, a calculator keypad in the middle, and some other buttons at the bottom :
This could be achieved with a vertical box layout, with flowlayouts at the top and bottom, and in the middle a grid layout with all the number keys.
But... without you showing a diagram of what you want its very difficult to say.

Here's an example of using multiple Layout Managers as you can see you can use more than one, but you should use more than one JPanel to achieve what you want.
Also a recommendation is: Don't extend from JFrame, instead create a JFrame object as I did in this example and here's why you shouldn't do that.
import java.awt.*;
import javax.swing.*;
public class LayoutManagersExample {
public static void main(String args[]) {
new LayoutManagersExample();
}
public LayoutManagersExample() {
JFrame frame = new JFrame("Layout Managers Example");
JPanel topPane = new JPanel();
JPanel midPane = new JPanel();
JPanel panesHolder = new JPanel();
JLabel label = new JLabel("Top label");
JTextField field = new JTextField();
field.setColumns(5);
topPane.setLayout(new FlowLayout());
midPane.setLayout(new GridLayout(3, 2));
topPane.add(label);
topPane.add(field);
midPane.add(new JButton("Button 1"));
midPane.add(new JButton("Button 2"));
midPane.add(new JButton("Hello I'm a button"));
midPane.add(new JButton("HEY! Click me :)"));
midPane.add(new JButton("I love you"));
midPane.add(new JButton("This is another button"));
panesHolder.setLayout(new BoxLayout(panesHolder, BoxLayout.Y_AXIS));
panesHolder.add(topPane);
panesHolder.add(midPane);
frame.add(panesHolder);
frame.setSize(400, 300);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocationRelativeTo(null);
}
}
And this is how it looks like:

How to place components at specific positions?

How to place components in layout on specific position.
Like I want to place 2 text boxes in first row, below 3 combo boxes.
But when I am trying to put they all appear in one line and I have used flowlayout. I have used the border as well. When I am resizing, the window sizes of the components are going out from border.
Can you suggest me some layouts to use and how to use it?
Here is my code :
topPanel=new JPanel();
topPanel.setLayout(new FlowLayout());
topPanel.setBorder(new TitledBorder(new EtchedBorder(), "Customer Data"));
CNameTextField = new JTextField (20); // create the Customer Name text field
CNameTextField.setEditable(true); // set editable text box
CIDLabel=new JLabel("Customer ID");
C_IDTextField = new JTextField (10);
C_IDTextField.setEditable(true); // set editable text box
topPanel.add(CNameTextField);
topPanel.add(C_IDTextField);
// Create and populate Room type combo box
roomTypeCombo = new JComboBox();
roomTypeCombo.addItem( "Budget($50)" );
// Create and populate Meal type combo box
mealCombo = new JComboBox();
mealCombo.addItem( "None" );
// Create and populate Days combo box
daysCombo = new JComboBox();
for(int i=0;i<31 ; i++) {
// populate combobox with days
daysCombo.addItem(i);
}
// Adding rest of the components to top panel
topPanel.add(roomTypeCombo);
topPanel.add(mealCombo);
topPanel.add(daysCombo);
Thanks.

The most specific type of layout is absolute positioning.
Warning: Absolute positioning should rarely, if ever, be used. There are many reasons why. Here is one: Absolute positioning (No layout manager) vs. absolute positioning in MiGlayout
- Thanks to user brimborium for the good idea of adding a warning.
That being said, here is how to use absolute positioning:
In your code above, instead of setting topPanel's layout to FlowLayout, set it to null.
topPanel.setLayout(null);
Later on in the code, right before you start adding components to topPanel, call the container's setBounds method:
someJComponent.setBounds(x-coord, y-coord, width, height);
So for example you created an instance of JComboBox() and named it roomTypeCombo, the following code shows how to absolutely position roomTypeCombo.
topPanel.setLayout(null);
// code...
roomTypeCombo = new JComboBox();
// code...
roomTypeCombo.setBounds(100, 100, 200, 50);
topPanel.add(roomTypeCombo);
The setBounds method, used above, has four parameters:
int x-coord - set roomTypeCombo's x-coordinate relative to
its parent, topPanel.
int y-coord - set roomTypeCombo's y-coordinate relative to its parent, topPanel.
int width - specify roomTypeCombo's width.
int height - specify roomTypeCombo's height.
I would just play around with the coordinates and see if you like anything that comes out of it. The worst thing that could happen is that you go back to using a layout, which is probably better than absolute positioning. Or you could implement your own layout manager, if you follow this hyperlink the first answer talks about implementing your own layout manager and has helpful links.
More information on absolute positioning

Try to change the layout.
http://docs.oracle.com/javase/tutorial/uiswing/layout/using.html
You could go for a GridLayout with two lines (for example, there is some others possible combinations), with each line containing respectively 3 JComboBoxs, and two JTextFields.
Look carefully at the documentation and check out some examples easily reachable on the web.
import java.awt.GridLayout;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
public class SwingResizeJFrame {
public SwingResizeJFrame() {
JTextField TextField1 = new JTextField("firstTextField");
JTextField TextField2 = new JTextField("secondTextField");
JPanel firstPanel = new JPanel();
firstPanel.setLayout(new GridLayout(0, 2, 10, 10));
firstPanel.add(TextField1);
firstPanel.add(TextField2);
JComboBox comboBox1 = new JComboBox(new Object[]{"Ester", "Jordi", "Jordina", "Jorge", "Sergi"});
JComboBox comboBox2 = new JComboBox(new Object[]{"Ester", "Jordi", "Jordina", "Jorge", "Sergi"});
JComboBox comboBox3 = new JComboBox(new Object[]{"Ester", "Jordi", "Jordina", "Jorge", "Sergi"});
JPanel secondPanel = new JPanel();
secondPanel.setLayout(new GridLayout(0, 3, 10, 10));
secondPanel.add(comboBox1);
secondPanel.add(comboBox2);
secondPanel.add(comboBox3);
JFrame frame = new JFrame();
frame.setLayout(new GridLayout(2, 1, 10, 10));
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(firstPanel);
frame.add(secondPanel);
frame.pack();
frame.setLocation(150, 150);
frame.setVisible(true);
}
public static void main(String[] args) {
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
SwingResizeJFrame demo = new SwingResizeJFrame();
}
});
}
}

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).