Develop Reference

Implementing BoxLayout in Java Swing [duplicate]

I have this Java JFrame class, in which I want to use a boxlayout, but I get an error saying java.awt.AWTError: BoxLayout can't be shared. I've seen others with this problem, but they solved it by creating the boxlayout on the contentpane, but that is what I'm doing here. Here's my code:
class EditDialog extends JFrame {
JTextField title = new JTextField();
public editDialog() {
setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
setTitle("New entity");
getContentPane().setLayout(
new BoxLayout(this, BoxLayout.PAGE_AXIS));
add(title);
pack();
setVisible(true);
}
}

Your problem is that you're creating a BoxLayout for a JFrame (this), but setting it as the layout for a JPanel (getContentPane()). Try:
getContentPane().setLayout(
new BoxLayout(getContentPane(), BoxLayout.PAGE_AXIS)
);

I've also found this error making this:
JPanel panel = new JPanel(new BoxLayout(panel, BoxLayout.PAGE_AXIS));
The JPanel isn't initialized yet when passing it to the BoxLayout. So split this line like this:
JPanel panel = new JPanel();
panel.setLayout(new BoxLayout(panel, BoxLayout.PAGE_AXIS));
This will work.

I think that one important thing to highlight from the previous answers is that the BoxLayout's target (the first parameter) should be the same Container that the setLayout method is being called upon as in the following example:
JPanel XXXXXXXXX = new JPanel();
XXXXXXXXX.setLayout(new BoxLayout(XXXXXXXXX, BoxLayout.Y_AXIS));

If you're using the layout on a JFrame like:
JFrame frame = new JFrame();
frame.setLayout(new BoxLayout(frame, BoxLayout.Y_AXIS));
frame.add(new JLabel("Hello World!"));
The control is actually being added to the ContentPane so it will look like it's 'shared' between the JFrame and the ContentPane
Do this instead:
JFrame frame = new JFrame();
frame.setLayout(new BoxLayout(frame.getContentPane(), BoxLayout.Y_AXIS));
frame.add(new JLabel("Hello World!"));

java.awt.AWTERROR When Creating a BoxLayout

I am trying to make a boxlayout filled with a Jlabel and 3 radio buttons in descending order. The program compiles fine but then errors out with the error BoxLayout cant be shared. I have seen people saying this error is because they are trying to attach it to a jframe, but in this case it is the jpanel being given the layout not a frame. This is the segment of code that compiles the window.
JPanel mainPanel = new JPanel();
mainPanel.setLayout(new BorderLayout());
JPanel effortButtons = new JPanel();
JPanel skillButtons = new JPanel();
effortButtons.setLayout(new BoxLayout(mainPanel, BoxLayout.Y_AXIS));
skillButtons.setLayout(new BoxLayout(mainPanel, BoxLayout.Y_AXIS));
effortButtons.add(effortHeader);//this is what gives the error
effortButtons.add(oneEffort);
effortButtons.add(twoEffort);
effortButtons.add(threeEffort);
skillButtons.add(skillHeader);
skillButtons.add(oneSkill);
skillButtons.add(twoSkill);
skillButtons.add(threeSkill);
mainPanel.add(effortButtons, BorderLayout.WEST);
mainPanel.add(skillButtons, BorderLayout.EAST);
mainPanel.add(studentName, BorderLayout.NORTH);
mainPanel.add(next, BorderLayout.SOUTH);
add(mainPanel);
pack();

// xxxxxxxxxxxxx xxxxxxxxx
effortButtons.setLayout(new BoxLayout(mainPanel, BoxLayout.Y_AXIS));
You have to pass into the BoxLayout constructor the component that is getting the layout. So this should be:
effortButtons.setLayout(new BoxLayout(efforButtons, BoxLayout.Y_AXIS));
Likewise for our other JPanel -- change it to:
skillButtons.setLayout(new BoxLayout(skillButtons, BoxLayout.Y_AXIS));
Per the BoxLayout API:
public BoxLayout(Container target, int axis)
target - the container that needs to be laid out

Adding labels to the next line of a BoxLayout

I have a box layout that has a JLabel and a button next to it, as such:
JFrame frame = new JFrame();
JPanel panel = new JPanel();
panel.setLayout(new BoxLayout(panel,BoxLayout.X_AXIS));
panel.add(new JLabel("Reference "));
panel.add(new JButton("HI"));
frame.add(panel);
frame.setSize(500,300);
frame.setVisible(true);
This correctly presents a label called reference and a button right next to it. But if I want to present the same thing right below it (a new label, and another button), how would I do that?
Because simply creating another panel, and emulating what I did before, doesn't seem to work.
I.e
JPanel newPanel = new JPanel();
newPanel.setLayout(new BoxLayout(panel,BoxLayout.X_AXIS));
Or using HTML in a new label like
JLabel s = new JLabel("<html> <br>newLaberl </html>");
adding this to the panel still would print it on the same line, after the button, not the next, any ideas?

You just have to set the layout of the JFrame get it working the way you said.
I used your example setting the frame layout to use a GridLayout
JFrame frame = new JFrame();
JPanel panel = new JPanel();
JPanel panel2 = new JPanel();
frame.setLayout(new GridLayout(2,1));
panel.setLayout(new BoxLayout(panel,BoxLayout.X_AXIS));
panel.add(new JLabel("Reference "));
panel.add(new JButton("HI"));
panel2.setLayout(new BoxLayout(panel2,BoxLayout.X_AXIS));
panel2.add(new JLabel("Reference2 "));
panel2.add(new JButton("HI2"));
frame.add(panel);
frame.add(panel2);
frame.setSize(500,300);
frame.setVisible(true);

boxlayout isn't maybe the best layout for such thing, i suggest you to go to
https://docs.oracle.com/javase/tutorial/uiswing/layout/layoutlist.html
and take a look on the various layout and tutorial documented on Oracle's docs website.
this one could be usefull for your application
https://docs.oracle.com/javase/tutorial/uiswing/layout/gridbag.html

Control sizing of JPanel

I have a typical IDE style window with a top JMenuBar and JToolBar,
a large center console and a bottom status bar.
Here are the main parts of the code:
mainPanel = new JPanel();
mainPanel.setLayout(new BorderLayout());
JPanel topPanel = new JPanel();
. (JMenuBar and JToolBar)
.
mainPanel.add(topPanel, BorderLayout.NORTH);
cardPanel = new JPanel();
cardPanel.setLayout(cardLayout);
.
.
Dimension minDimension = new Dimension(680, 400);
Dimension maxDimension = new Dimension(750, 800);
JPanel centerPanel = new JPanel();
centerPanel.setMinimumSize(minDimension);
centerPanel.setPreferredSize(minDimension);
centerPanel.setMaximumSize(maxDimension);
centerPanel.setLayout(new BoxLayout(centerPanel, BoxLayout.Y_AXIS));
centerPanel.add(cardPanel);
mainPanel.add(centerPanel, BorderLayout.CENTER);
mainPanel.add(statusBar, BorderLayout.SOUTH);
I want to be able to control the sizing of the whole window,
with a minimum and maximum size.
I thought I could have the 'centerPanel' JPanel as a BoxLayout,
so I could have some control over it, but as it is, I can't
control the sizing of the window at all.
I tried to make the 'mainPanel' use a BoxLayout, instead of a BorderLayout, but there
where too many issues.
Is the main BorderLayout causing it to "ignore" the sizing?
I know that the parts, other than the center, have some sizing
control, that's why I tried to use a BoxLayout in the center.
Is it possible to keep the BorderLayout, and get it to work,
with some other modifications, or would I need to switch to some other Layout Manager?
Thanks!

Layout Manager preferredSize Java

I'm still trying to learn how layout managers work. I made a Frame with two JPanels.
The first one contains a textArea with a boxLayout.
The second one contains a flow layout with a button.
I set the preferredSize of each panel accordingly, packed them, but got unexpected results.
import java.awt.*;
import javax.swing.*;
public class LayoutMgrTest
{
public static void main(String[] args)
{
TableBasic frame = new TableBasic();
frame.setDefaultCloseOperation( EXIT_ON_CLOSE );
frame.setVisible(true);
frame.getContentPane().setLayout(new GridLayout(2,1));
JPanel controlPane = new JPanel();
JPanel buttonPane = new JPanel();
controlPane.setLayout(new BoxLayout(controlPane, BoxLayout.PAGE_AXIS));
controlPane.setPreferredSize(new Dimension(200, 200));
controlPane.add(new JScrollPane(new JTextArea()));
buttonPane.setLayout(new FlowLayout(FlowLayout.LEFT));
buttonPane.setPreferredSize(new Dimension(100,20));
buttonPane.add(new JButton("Button1"));
buttonPane.add(new JButton("Button2"));
frame.getContentPane().add(controlPane, BorderLayout.NORTH);
frame.getContentPane().add(buttonPane, BorderLayout.SOUTH);
frame.setSize(new Dimension(500,500));
frame.pack();
}
}
Whatever I do, if I use a grid Layout, it seems to always allocate half of the available space to each control. I have been told that:
The height of each row is dependent on the height of each component
added in each row.
The buttonpane's height is 20. It's allocating much more than that to it:
What's wrong with this code?
I would like to leave the two JPanels intact please. It's easy to simply add the textbox and the buttons directly to the frame, but I need to do it with JPanels (because I will be adding borders and other things).

That's the result of using GridLayout as layout manager. Change it to BorderLayout:
frame.getContentPane().setLayout(new BorderLayout());
For example, this code (I changed a little as possible from the original):
import java.awt.*;
import javax.swing.*;
public class LayoutMgrTest
{
public static void main(String[] args)
{
JFrame frame = new JFrame();
frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
//frame.setVisible(true);
//frame.getContentPane().setLayout(new BorderLayout());
JPanel controlPane = new JPanel();
JPanel buttonPane = new JPanel();
controlPane.setLayout(new BoxLayout(controlPane, BoxLayout.PAGE_AXIS));
controlPane.setPreferredSize(new Dimension(200, 200));
controlPane.add(new JScrollPane(new JTextArea()));
buttonPane.setLayout(new FlowLayout(FlowLayout.LEFT));
buttonPane.setPreferredSize(new Dimension(100,40));
buttonPane.add(new JButton("Button1"));
buttonPane.add(new JButton("Button2"));
frame.add(controlPane, BorderLayout.NORTH);
frame.add(buttonPane, BorderLayout.SOUTH);
//frame.setSize(new Dimension(500,500));
frame.pack();
frame.setVisible(true);
}
}
Generates this frame:

I set the preferredSize of each panel accordingly,
That is another problem. You should NOT set the preferred size. That is the job of the layout manager. Just add your components to the panels and let the layout manager do its job.
Most compnents have a default preferred size. For some you need to give it a little tip.
For example when using a text area you would give a "suggested" preferred size by using:
JTextArea textArea = new JTextArea(rows, columns);

If you use LayoutManager, you should not set a size on a component except the frame.
the size for the components is calculated from the different layout managers.
you find more infos at http://download.oracle.com/javase/tutorial/uiswing/layout/howLayoutWorks.html
in your code, you can add the panel with the textarea to BorderLayout.CENTER. this should solve your problem. the component in BorderLayout.CENTER takes the whole space, except the space needed for the components in NORTH, EAST, SOUTH and WEST.