Develop Reference

How to Keep JCheckBox Horizontally inside JPanel

I have a JPanel. Inside Panel I have kept one JLabel and three JCheckBox.
I want to keep all the checkBox in one line after JLabel. Here is the sample code and some screenshots.
Output 1
Output 2
When i change to X_AXIS it is coming everything in one line and when i switch to Y_AXIS then it is coming new line means vertically.
But my requirement is all the checkbox should come next line means after JLabel.
JLabel should come in line and all the checkBox should come in one line.
public class CheckBoxWithJLabel {
public static void main(String[] args) {
JFrame f= new JFrame("CheckBox Example");
JPanel panel = new JPanel();
panel.setBounds(40,80,600,200);
JCheckBox chk_Embrodary=new JCheckBox("Embrodary");
JCheckBox chk_Cutting=new JCheckBox("Cutting");
JCheckBox cb_Sewing=new JCheckBox("Sewing");
panel.setLayout(new javax.swing.BoxLayout(panel, javax.swing.BoxLayout.X_AXIS));
JLabel lblHeader=new JLabel("Job Work Process Selection");
panel.add(lblHeader);
panel.add(chk_Embrodary);
panel.add(chk_Cutting);
panel.add(cb_Sewing);
f.add(panel);
f.setSize(600,400);
f.setLayout(null);
f.setVisible(true);
}
}
I want this output like
this
How to solve this problem?

I would highly suggest you to have a look through the Java Swing Tutorial, especially the Laying Out Components Within a Container section, since it seems you lack some basic understanding of how Swing and its Layout Managers are supposed to be used.
Regarding your problem:
Currently, you are using a single BoxLayout, which " puts components in a single row or column". You only want that behavior for your JCheckBoxes though, and not for your JLabel. Keeping this in mind, the solution is to split up your components and to not put all of them in a single JPanel. Doing this will grant you more flexibility in how you design your GUI, since you can use multiple layouts in different nested panels.
You could do something like this (explanation in the code comments):
public static void main(String[] args) {
JFrame f = new JFrame("CheckBox Example");
// add a Y_AXIS boxlayout to the JFrames contentpane
f.getContentPane().setLayout(new BoxLayout(f.getContentPane(), BoxLayout.Y_AXIS));
JCheckBox cbEmbrodary = new JCheckBox("Embrodary");
JCheckBox cbCutting = new JCheckBox("Cutting");
JCheckBox cbSewing = new JCheckBox("Sewing");
// no need to set the bounds, since the layoutmanagers will determine the size
JPanel labelPanel = new JPanel(); // default layout for JPanel is the FlowLayout
JLabel lblHeader = new JLabel("Job Work Process Selection");
labelPanel.add(lblHeader); // JPanel for the label done
// JPanel for the comboboxes with BoxLayout
JPanel cbPanel = new JPanel();
cbPanel.setLayout(new BoxLayout(cbPanel, BoxLayout.X_AXIS));
cbPanel.add(cbEmbrodary);
cbPanel.add(cbCutting);
cbPanel.add(cbSewing);
f.add(labelPanel);
f.add(cbPanel);
// No need to set the size of the JFrame, since the layoutmanagers will
// determine the size after pack()
f.pack();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setVisible(true);
}
Output:
Sidenotes:
Don't set fixed sizes via setSize() or setBounds() to your components. Swing is designed to be used with appropariate LayoutManagers, and if you do that, calling pack() on the JFrame before setting it visible will layout the components and determine their appropriate size. (Also, don't use null-layout for the same reasons)
If you need the JLabel to not be centered but left aligned, like in your screenshot, then use the following:
FlowLayout layout = (FlowLayout) labelPanel.getLayout();
layout.setAlignment(FlowLayout.LEFT);

How to create a fluid 2-column GridLayout within a ScrollPane?

I have done tons of searching over the past two hours, and I've given up. The image below shows what I am trying to achieve (don't judge my drawing it's late and I made it in paint quickly):
Basically, I want a JScrollPane to have a JPanel with a 2-column GridLayout, and as I add elements I want the GridLayout to expand downward. I want the elements to use their Preferred Size and to NOT expand within the GridLayout.
Currently I have a JScrollPane and a JPanel with a GridLayout, and a JPanel containing the grid with a FlowLayout. As a test, I add 10 buttons to the grid. Here's my current code:
// Setup main panel
JPanel pnlUsers = new JPanel(new GridLayout(0, 2));
pnlUsers.setOpaque(true);
pnlUsers.setBackground(Color.GREEN);
// Setup GridLayout Container
JPanel pnl2 = new JPanel();
pnl2.setOpaque(false);
pnl2.add(pnlusers);
// Setup scrollpane
JScrollPane scrUsers = new JScrollPane(pnl2);
scrUsers.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);
scrUsers.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
scrUsers.setOpaque(false);
scrUsers.getViewport().setOpaque(false);
scrUsers.setBorder(null);
// Add users
for (int i = 0; i < 10; i++) {
pnlUsers.add(new JButton("Button " + (i + 1));
}
This gives a very good result, with the buttons using their preferred size as seen in the image below:
Unfortunately, the buttons are still not filling the horizontal space. So, I attempted to make pnl2 a BoxLayout instead and add some vertical glue...
// Setup GridLayout Container
JPanel pnl2 = new JPanel();
pnl2.setLayout(new BoxLayout(pnl2, BoxLayout.Y_AXIS));
pnl2.setOpaque(false);
pnl2.add(pnlusers);
pnl2.add(Box.createVerticalGlue());
I also created my own temporary button class that sets the preferred size to use the minimum size:
public class TempButton extends JButton {
public PLTempButton(String msg) {
super(msg);
this.setPreferredSize(this.getMinimumSize());
}
}
Which resulted in the following:
This is much better, but there's still a problem. If there are not enough buttons to cause the JScrollPane to scroll, the buttons height are not consistent and will resize as you resize the window vertically. Why?
Obviously when I add 100 buttons, they use their preferred size:
Maybe I'm just not understanding the differences between minimum, preferred and maximum size? But I want the buttons to use the height they're set even if there aren't enough to cause the scroll-pane to, well, scroll. What can I do to fix this?

1) How do I even get a GridLayout within a ScrollPane?
Create a JPanel
Apply a GridLayout to the JPanel
Wrap the JPanel in a JScrollPane
For example
JPanel panel = new JPanel(new GridLayout(0, 2));
JScrollPane scrollPane = new JScrollPane(panel);
// Add the scroll pane to what ever parent container you're using
2) How do I get said GridLayout to expand horizontally, including the added components?
That doesn't make sense with regards to all previous part of the question, you said "and have it slowly expand downward the more things I add"
Having said that, the "basic" answer is, you configure the GridLayout and let it do it's job. The above example is configured for 2 columns and n number of roes
3) How would I add a "margin" to the components?
That's a broad answer, you could:
Make use of the horizontal and vertical gap properties of the GridLayout
Use a compound layout and adjust the insets of the an appropriate layout manager (like GridBagLayout)
Recommendations
I would recommend reading through Laying Out Components Within a Container to get a better understanding of the layout managers.
Remember, you not stuck to using one.
I would also recommend reading through How to Use Scroll Panes as you're asking basic questions about the API which are better covered through the tutorials

The following mre demonstrates creating a JPanel with GridLayout warped by JScrollPane and setting its horizontal and vertival gaps.
The Jpanel is added using a BorderLayout (the default layout manager of JFrame content pane) which allows it to expand:
import java.awt.BorderLayout;
import java.awt.GridLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
public class SwingMain {
private String text ="Growing ";
private JPanel grid;
private JFrame f;
SwingMain() {
creategui();
}
void creategui(){
f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setLocationRelativeTo(null);
JButton addComponentBtn = new JButton("Add Component");
addComponentBtn.addActionListener(e-> addComponent());
f.add(addComponentBtn, BorderLayout.PAGE_START);
grid = new JPanel(new GridLayout(0, 2, 10, 10)); //any number of rows, 2 columns, H and V gap
f.add(new JScrollPane(grid), BorderLayout.CENTER);
f.pack();
f.setVisible(true);
}
void addComponent() {
grid.add(new JLabel(text) );
text +="."; //make text longer so JLable grows
f.pack();
}
public static void main(String[] args) {
new SwingMain();
}
}

Use BorderLayout to create two even columns

I'm trying to create a program using BorderLayout() that I want to look like this (but with even left right height and such)
although I am having trouble resizing the two JPanels (two boxes within the large box). At the moment my GUI looks like this,
I believe it is due to the CENTER still being there, I looked up on how to remove it but could not get it to work,
Question
Can can I edit this so that it will look like the top image.
package fuelstation;
import java.awt.*;
import java.util.*;
import javax.swing.*;
public class Fuelstation extends JFrame {
JButton btn1 = new JButton("Random Button");
public Fuelstation() {
JFrame frame = new JFrame("Fuel Station");
frame.setLayout(new BorderLayout());
frame.setResizable(false);
frame.setPreferredSize(new Dimension(500,350));
frame.setMaximumSize(new Dimension(500,350));
// Left Hand Side
JPanel lhs = new JPanel();
JTextArea tf_list = new JTextArea();
tf_list.setEditable(false);
tf_list.setWrapStyleWord(true);
tf_list.setText("This is a list of items");
lhs.add(tf_list);
tf_list.setSize(245, 325);
lhs.setBorder(BorderFactory.createTitledBorder("Left"));
// Left Hand Side End
// Right Hand Side
JPanel rhs = new JPanel();
rhs.setAlignmentX(Component.CENTER_ALIGNMENT);
rhs.setBorder(BorderFactory.createTitledBorder("Right"));
rhs.add(btn1);
tf_list.setSize(245, 325);
JPanel center = new JPanel();
center.setSize(0, 0);
// Right Hand Side End
frame.add(lhs, BorderLayout.WEST);
frame.add(center, BorderLayout.CENTER);
frame.add(rhs, BorderLayout.EAST);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
Fuelstation gui = new Fuelstation();
}
}

You need to drop the requirement to use a BorderLayout. The resizing policy for components when using a BorderLayout is stated in the class javadoc
The components are laid out according to their preferred sizes and the constraints of the container's size. The NORTH and SOUTH components may be stretched horizontally; the EAST and WEST components may be stretched vertically; the CENTER component may stretch both horizontally and vertically to fill any space left over.
By forcing your JFrame to a certain size
frame.setResizable(false);
frame.setPreferredSize(new Dimension(500,350));
frame.setMaximumSize(new Dimension(500,350));
your center component will take the extra width, as the EAST and WEST component will only stretch vertically.
So you need to use another LayoutManager. You can use the Visual guide to layout managers to get a grasp of the available LayoutManagers and their capabilities. That document states that a GridLayout would be a good candidate:
GridLayout simply makes a bunch of components equal in size and displays them in the requested number of rows and columns

java use size of JPanel to size components

Is it possible to use the size of a JPanel to set the size of components inside the JPanel? When I try to use getHeight() or getWidth() on the JPanel it always returns 0. I know that it gets it's size once the JFrame is packed, but how would one go about using the dimensions of the JPanel and applying it to a component inside it? Something like this
JPanel panel = new JPanel();
JLabel label = new JLabel();
label.setWidth(panel.getWidth());
panel.add(label);
EDIT:
See sample code below. What should I do if I want my Jlabel to be as wide as my JPanel? Is it wrong to use boxlayout in this case?
public class Main extends JFrame{
public Main(){
JPanel panel = new JPanel();
panel.setLayout(new BoxLayout(panel, BoxLayout.PAGE_AXIS));
panel.setBorder(BorderFactory.createLineBorder(Color.blue));
JLabel label = new JLabel();
label.setBorder(BorderFactory.createLineBorder(Color.red));
label.setText("label1");
label.setMinimumSize(panel.getPreferredSize());
label.setPreferredSize(panel.getPreferredSize());
panel.add(label);
add(panel);
setDefaultCloseOperation(EXIT_ON_CLOSE);
pack();
setSize(500,500);
setVisible(true);
}
public static void main(String[] args)
{
new Main();
}
}

Is it possible to use the size of a JPanel to set the size of components inside the JPanel?
This is the job of the layout manager.
When I try to use getHeight() or getWidth() on the JPanel it always returns 0
When the layout manager is invoked the Container will have a valid size so the layout manager can do its job properly.
There is no reason for you to be playing with sizes. Leave it to the layout managers to do their jobs.
Update:
What should I do if I want my Jlabel to be as wide as my JPanel? Is it wrong to use boxlayout in this case?
The BoxLayout attempts to respect the minimum/maximum size of the component. In you case you should be able to do something like:
JLabel label new JLabel("some text");
label.setBorder(....);
Dimension d = label.getPreferredSize();
d.width = 32767;
label.setMaximumSize( d );
Or maybe a simpler approach is to start with a BorderLayout. You can add the label to the NORTH. Then create another panel and add it to the CENTER.

Of course you can, but be careful that the result depends on the layout manager of your JPanel and on the number of its child components.

Setting the width ignores resizing. LayoutManagers typically ask components for their preferred widths and heights, and expand / contract items to maintain a visually appealing position after the frame has been resized. So, your best option is to leverage the layout manager and report a "preferred width".
You can use setPreferredWidth(...); but, if your preferred width is to change over the run of the program (due to window size changes), you will need to listen to the panel in question and update your button's preferred width as the panel's preferred width changes (this assumes it changes, which might not be true).

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).