Develop Reference

JFrame/BoxLayout weird size behavior

I am trying to set the sizes of my JButtons in a JPanel with BoxLayout correctly, but the behavior is beyond weird.
It will take the height from JButton.setPreferredSize, but completely ignore the width. This also only works when all buttons are set to the same height. As soon as one is smaller, it will revert all of them to some random minimum size (which isn't even the same for all buttons)
My code is this:
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(800, 500);
JPanel rightPanel = new JPanel();
JPanel leftPanel = new JPanel();
leftPanel.setLayout(new BoxLayout(leftPanel, BoxLayout.PAGE_AXIS));
JButton bBookmarks = new JButton("Bookmarks");
bBookmarks.setPreferredSize(new Dimension(200, 100));
//more buttons with same size
leftPanel.add(bBookmarks);
//more buttons
JSplitPane mainPanel = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, leftPanel, rightPanel);
mainPanel.setDividerLocation(200);
frame.add(mainPanel);
frame.setResizable(false);
frame.setVisible(true);
This creates this image.
The middle button is always wider than the rest as well. Using frame.pack() doesn't do anything except resizing the frame because the right panel is empty.
What am I doing wrong?
Edit: Should look like this:

Divide and conquer: break the design into small, easy to layout containers. In this case do not place the buttons directly in the left (BoxLayout) container but in a nested JPanel using GridLayout manager.
This ensures that all buttons have the same size:
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocationRelativeTo(null);
//add all buttons to a panel using a GridLayout which shows all components having the same size
JPanel buttons = new JPanel(new GridLayout(0,1));
JButton bBookmarks = new JButton("Bookmarks"); buttons.add(bBookmarks);
JButton bPlotter = new JButton("Plotter"); buttons.add(bPlotter);
JButton bShips = new JButton("Ships"); buttons.add(bShips);
//add buttons and text area to a panel using BoxLayout
JPanel leftPanel = new JPanel();
leftPanel.setPreferredSize(new Dimension(100,400));
leftPanel.setLayout(new BoxLayout(leftPanel, BoxLayout.PAGE_AXIS));
leftPanel.add(buttons);
leftPanel.add(new TextArea(10,30));
JPanel rightPanel = new JPanel();
rightPanel.setPreferredSize(new Dimension(600,400));
rightPanel.add(new JLabel("right pane"));
JSplitPane mainPanel = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT,true, leftPanel, rightPanel);
frame.add(mainPanel);
frame.pack();
frame.setVisible(true);

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!"));

How can I make a layout like the attached image

I am trying to design a layout which contains a form and couple of items. but I found it too hard to put items in right places.
In the following image, the right frame is what I am aiming to design and the left on is what I could made.
And this is the code for the right frame:
public class GUI extends JFrame{
public GUI(){
JFrame frame = new JFrame("frame");
frame.setSize(600, 600);
JPanel panel = new JPanel(new BorderLayout());
panel.add(new JLabel("Title"), BorderLayout.NORTH);
JPanel formPanel = new JPanel(new GridLayout(1,2));
panel.add(formPanel);
TitledBorder formPanelTitle = BorderFactory.createTitledBorder("GridLayout(1,2)");
formPanel.setBorder(formPanelTitle);
//LEFT PANEL
JPanel labelsPanel = new JPanel(new GridLayout(4,1));
TitledBorder labelsPanelTitle = BorderFactory.createTitledBorder("GridLayout(4,1)");
labelsPanel.setBorder(labelsPanelTitle);
labelsPanel.add(new JLabel("Label 1"));
labelsPanel.add(new JLabel("Label 2"));
labelsPanel.add(new JLabel("Label 3"));
labelsPanel.add(new JLabel("Label 4"));
formPanel.add(labelsPanel);
//RIGHT PANEL
JPanel fieldsPanel = new JPanel(new GridLayout(4,1));
TitledBorder fieldsPanelTitle = BorderFactory.createTitledBorder("GridLayout(4,1)");
fieldsPanel.setBorder(fieldsPanelTitle);
fieldsPanel.add(new JTextField("Label 1"));
fieldsPanel.add(new JTextField("Label 2"));
fieldsPanel.add(new JTextField("Label 3"));
fieldsPanel.add(new JTextField("Label 4"));
formPanel.add(fieldsPanel);
//BOTTOM PANEL
JPanel bottomPanel = new JPanel(new GridLayout(2,1));
TitledBorder BottomPanelTitle = BorderFactory.createTitledBorder("GridLayout(2,1)");
bottomPanel.setBorder(BottomPanelTitle);
panel.add(bottomPanel, BorderLayout.SOUTH);
JPanel buttonPanel = new JPanel(new FlowLayout());
buttonPanel.add(new JButton("Browse"));
buttonPanel.add(new JLabel("Label"));
TitledBorder buttonPanelTitle = BorderFactory.createTitledBorder("FlowLayout()");
buttonPanel.setBorder(buttonPanelTitle);
bottomPanel.add(buttonPanel);
JPanel secondButtonPanel = new JPanel(new GridLayout(1,2));
secondButtonPanel.add(new JButton("Back"));
secondButtonPanel.add(new JButton("Next"));
TitledBorder secondButtonPanelTitle = BorderFactory.createTitledBorder("GridLayout(1,2)");
secondButtonPanel.setBorder(secondButtonPanelTitle);
bottomPanel.add(secondButtonPanel);
frame.add(panel);
frame.setLocationRelativeTo(null);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
public static void main(String[] args) {
// TODO code application logic here
new GUI();
}
}
I am not sure if the code is really optimal, since there are a lot of inner panels and made it too complicated. Also I could not put items in the places I wanted to. Is there any suggestion or idea to make this layout look better?

Create a JPanel, using GridBagLayout and add your labels/fields to it, this forms the "center" portion of your layout.
Create a JPanel and add the Browse button a JLabel to it. Using GridBagConstraints#gridwidth set to REMAINDER, add this to your first panel
Create a JPanel, using BorderLayout, add the first panel to the CENTER position. Add the title Label to the NORTH position, you may need to adjust it's horizontalAlignment property
Create a JPanel using FlowLayout, aligned to the RIGHT and add your "Back" and "Next" buttons to it. Add this to the SOUTH position of the previous panel.
Check out Laying Out Components Within a Container for more details

Adding components into JPanel inside a JFrame

Since im a beginner and i don't want to get involved with the layout managers, i was simply adding a JPanel into my main JFrame and giving spesific location to each component in the panel. But somehow the output appears way too wrong..
frame = new JFrame(email + " (Offline)");
frame.setSize(400, 400);
frame.setLocation(0, 0);
frame.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
frame.setLayout(new FlowLayout());
frame.addWindowListener(new WindowAdapter()
{
public void windowClosing(WindowEvent e)
{
// out.println("BYE");
// out.flush();
frame.dispose();
thread.stop();
}
});
panel = new JPanel();
frame.add(panel);
chat = new JTextArea();
chat.setSize(400, 200);
chat.setLocation(0, 0);
chat.setEditable(false);
panel.add(chat);
panel.validate();
JLabel you = new JLabel("You:");
you.setSize(you.getPreferredSize());
you.setLocation(0, 210);
panel.add(you);
panel.validate();
input = new JTextArea();
input.setSize(200, 200);
input.setLocation(0, 220 + chat.getSize().height);
panel.add(input);
panel.validate();
send = new JButton("Send");
send.setSize(send.getPreferredSize());
send.setLocation(210, 220 + chat.getSize().height);
panel.add(send);
panel.validate();
frame.setVisible(true);
The outcome of this frame is that text areas are invisible, a You: label in the middle and next to the right of it the button.. What am i missing here?

Again, don't use null layout since it makes updating and maintaining your GUI much more difficult than it should be, and can lead to ugly GUI's if you plan on having them run on multiple platforms. Instead
Use several JPanels, each one holding a core group of components and each using its best layout manager
Nest these JPanels in other JPanels that use the best layout manager to display them
and that will allow your GUI to be resizeable without need of extra code.
Put your JTextAreas in JScrollPanes so that you can see all text even if it goes beyond the text area.
Never set the size of the JTextArea as that will not allow it to scroll. Instead set its columns and rows.
As a very simple example, run this to see what I mean:
import java.awt.*;
import javax.swing.*;
public class FooSwing2 {
public static void main(String[] args) {
JTextArea chatArea = new JTextArea(8, 40);
chatArea.setEditable(false);
chatArea.setFocusable(false);
JScrollPane chatScroll = new JScrollPane(chatArea);
JPanel chatPanel = new JPanel(new BorderLayout());
chatPanel.add(new JLabel("Chat:", SwingConstants.LEFT), BorderLayout.PAGE_START);
chatPanel.add(chatScroll);
JTextField inputField = new JTextField(40);
JButton sendBtn = new JButton("Send");
JPanel inputPanel = new JPanel();
inputPanel.setLayout(new BoxLayout(inputPanel, BoxLayout.LINE_AXIS));
inputPanel.add(inputField);
inputPanel.add(sendBtn);
JPanel youLabelPanel = new JPanel(new FlowLayout(FlowLayout.LEFT, 0, 0));
youLabelPanel.add(new JLabel("You:"));
JPanel mainPanel = new JPanel();
mainPanel.setLayout(new BoxLayout(mainPanel, BoxLayout.PAGE_AXIS));
mainPanel.add(chatPanel);
mainPanel.add(Box.createVerticalStrut(10));
mainPanel.add(youLabelPanel);
mainPanel.add(inputPanel);
JFrame frame = new JFrame("Foo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(mainPanel);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
}
This would result in a simple (non-functioning) GUI that looked like this:
Now say you want to change this and add another button, an "exit" JButton to the right of the send JButton. If you used null layout, you'd have to resize your GUI, you'd have to move the send button over to the left and make sure that your math was without error, etc. If you used layout managers, you'd need just two new lines of code (to change the display, not the functionality of course):
JTextField inputField = new JTextField(40);
JButton sendBtn = new JButton("Send");
JButton exitBtn = new JButton("Exit"); // ***** added
JPanel inputPanel = new JPanel();
inputPanel.setLayout(new BoxLayout(inputPanel, BoxLayout.LINE_AXIS));
inputPanel.add(inputField);
inputPanel.add(sendBtn);
inputPanel.add(exitBtn); // ***** added
That's it, and this would display:

setAlignmentY not centering JLabel in BorderLayout

new to java and brand new to the site. I have a JLabel added to the center panel of a BorderLayout. I would like the JLabel to be centered in the panel; setAlignmentX appears to work, but setAlignmentY does not (the label appears at the top of the panel). Here is the code:
centerPanel = new JPanel();
centerPanel.setLayout(new BoxLayout(centerPanel,BoxLayout.Y_AXIS));
JLabel label = new JLabel("This should be centered");
label.setAlignmentX(Component.CENTER_ALIGNMENT);
label.setAlignmentY(Component.CENTER_ALIGNMENT);
centerPanel.add(label);
contentPane.add(centerPanel, BorderLayout.CENTER);
I have also tried label.setVerticalAlignment(CENTER);, to no avail. I've looked for an answer in the API and in the Java Tutorials, on this site, and through a google search. Thanks!

You were close, try this:
public static void main(String[] args)
{
JFrame contentPane = new JFrame();
JPanel centerPanel = new JPanel();
centerPanel.setLayout(new BorderLayout());
JLabel label = new JLabel("This should be centered");
label.setHorizontalAlignment(SwingConstants.CENTER);
centerPanel.add(label, BorderLayout.CENTER);
contentPane.add(centerPanel, BorderLayout.CENTER);
contentPane.pack();
contentPane.setVisible(true);
}
One of the many joys of GUI programming in Java. I'd rather poke my eye out if I'm being honest.

I tried to vertically center align JButton but I had problem it was stretched. After fiddling I found this works:
JPanel jpTop = new JPanel(new BorderLayout());
jbStop = new JButton("Cancel");
JPanel extraPanel = new JPanel();
extraPanel.setLayout(new BoxLayout(extraPanel, BoxLayout.X_AXIS));
extraPanel.setAlignmentY(Component.CENTER_ALIGNMENT);
extraPanel.add(jbStop);
jpTop .add(extraPanel, BorderLayout.EAST);
Of course it works as well for JLabel.