Develop Reference

Set minimum width in side panel of Swing BorderLayout

I understand some parts of BorderLayout -- e.g., the EAST/WEST (or BEGINNING_OF_LINE/END_OF_LINE) panel component stays one width and its length is stretched with the length of the window.
I want to put a panel on the WEST side that itself has multiple components - a panel of buttons and a JList of things the buttons control, in this case. I would like to allocate a minimum width for the strings in that JList, but something (probably BorderLayout) prevents me from setting a minimum or preferred width.
When I run the code below, the list in the left panel is wide enough for "LongNameGame 3", but only because I added the string before rendering the list. I would like to set the width of that JList to accommodate strings of the width of my choice. Later I'll put it in a ScrollPane for strings wider than that, but that's a different problem.
My question is not answered by referring me to other layout managers -- I want to know how to do this with BorderLayout, if possible.
package comm;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.GridLayout;
import java.util.Vector;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JList;
import javax.swing.JPanel;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.border.Border;
public class BLPlay
{
public static void main(String ... arguments)
{
JFrame frame = buildLoungeFrame();
frame.setVisible(true);
}
private static JFrame buildLoungeFrame()
{
JFrame loungeFrame = new JFrame("BLPlay");
loungeFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
loungeFrame.setLayout(new BorderLayout(10,10));
// left panel is another BorderLayout panel with buttons and a list of games
JPanel gameListControlPanel = new JPanel(new BorderLayout());
Border innerBorder = BorderFactory.createLineBorder(Color.BLACK, 2);
Border outerBorder = BorderFactory.createEmptyBorder(3,3,3,3);
gameListControlPanel.setBorder(BorderFactory.createCompoundBorder(outerBorder, innerBorder));
String[] gamePanelButtonLabels = { "New", "Join", "Leave", "End" };
JPanel gamePanelButtons = new JPanel(new GridLayout(gamePanelButtonLabels.length,1));
addButtons(gamePanelButtons, gamePanelButtonLabels);
JPanel gamePanelButtonsContainerPanel = new JPanel();
gamePanelButtonsContainerPanel.add(gamePanelButtons);
gameListControlPanel.add(gamePanelButtonsContainerPanel, BorderLayout.WEST);
Vector<String> gameList = new Vector<>();
gameList.add("Game 1");
gameList.add("Game 2");
gameList.add("LongNameGame 3");
JList<String> gameJList = new JList<>(gameList);
JPanel gameListPanel = new JPanel(new FlowLayout());
gameListPanel.setMinimumSize(new Dimension(600,600)); // <-- has no effect
gameListPanel.add(gameJList);
gameListControlPanel.add(gameListPanel, BorderLayout.EAST);
loungeFrame.add(gameListControlPanel, BorderLayout.WEST);
// center panel in the lounge is for chat messages; it has a separate border layout,
// center for accumulated messages, bottom for entering messages
JPanel chatMessagePanel = new JPanel(new BorderLayout());
// Border chatMessagePanelBorder = BorderFactory.createEmptyBorder(7,7,7,7);
// chatMessagePanel.setBorder(chatMessagePanelBorder);
JTextArea chatMessages = new JTextArea();
chatMessagePanel.add(chatMessages, BorderLayout.CENTER);
// debug
chatMessages.append("message one\n");
chatMessages.append("message two\n");
chatMessages.append("message three\n");
// and lower panel is for entering one's own chat messages
JPanel chatMessageEntryPanel = new JPanel(new FlowLayout(FlowLayout.LEFT));
JTextField chatMessageEntryField = new JTextField(35);
JButton chatMessageEntryButton = new JButton("Enter");
chatMessageEntryPanel.add(chatMessageEntryField);
chatMessageEntryPanel.add(chatMessageEntryButton);
chatMessagePanel.add(chatMessageEntryPanel, BorderLayout.SOUTH);
loungeFrame.add(chatMessagePanel, BorderLayout.CENTER);
loungeFrame.pack();
return loungeFrame;
}
private static void addButtons(JPanel panel, String ... labels)
{
for (String label : labels)
{
JButton button = new JButton(label);
panel.add(button);
}
}
}

Give the JList a prototype cell value that is wide enough to display what you need. e.g.,
gameJList.setPrototypeCellValue("xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx");
The prototype value (here a String because the list has been declared as a JList<String>) is used to set the list's preferred size, but is not displayed in the JList. You can use as large or small a list as you need. Also be sure to set visible row count for the same purpose in the horizontal dimension:
gameJList.setVisibleRowCount(20); // for example

How can I display 2 different panels at the same time?

My first panel's layout is BorderLayout and my second panel's layout is GridBagLayout. I don't know how to show them both at the same time.
I already tried adding two panels to on another panel.

Adding both to another panel is the way to go! But you have to make the right choice of LayoutManager for this "parent" panel. Let me give you an example:
The JFrame's content pane (where you add all your Components to) can be setup with a LayoutManager of your choice. See this runnable example, which creates two JPanels of 100x100 pixels in different colors. The panels are using the LayoutManagers you mentioned, but the main content pane of the JFrame is set to a BoxLayout (horizontal, but you can also set it to vertical!).
You can do this to any other panel, too. A panel.setLayout(new BoxLayout(panel, BoxLayout.X_AXIS)); is enough. The below example just uses the content pane, but you can adapt it to your needs:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.GridBagLayout;
import javax.swing.BoxLayout;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class TwoPanels extends JFrame {
private static final long serialVersionUID = 1L;
private static final Dimension DEFAULT_DIMENSION = new Dimension(100, 100);
public static void main(String[] args) {
new TwoPanels();
}
public TwoPanels() {
//create panel 1
JPanel panel1 = new JPanel(new BorderLayout());
panel1.setPreferredSize(DEFAULT_DIMENSION);
panel1.setBackground(Color.RED);
//create panel 2
JPanel panel2 = new JPanel(new GridBagLayout());
panel2.setPreferredSize(DEFAULT_DIMENSION);
panel2.setBackground(Color.GREEN);
//set content pane layout
setLayout(new BoxLayout(this.getContentPane(), BoxLayout.X_AXIS));
//add to content pane
add(panel1);
add(panel2);
//setup and display window
pack();
setVisible(true);
}
}
It looks like this:
EDIT: It's a little unclear from your question that you actually want to stack overlaying panels. You might find what you need here: https://docs.oracle.com/javase/tutorial/uiswing/components/layeredpane.html

Java Swing UI Layout

I am creating a basic user interface in Swing and was hoping for some help. Below is a screenshot of what I am trying to achieve:
My code currently is as follows:
package testui;
import java.awt.Container;
import javax.swing.*;
public class TestUI{
private JTextField outputArea = new JTextField();
private JTextField errorReportArea = new JTextField();
private JPanel inputPanel = new JPanel();
private JLabel nameLabel = new JLabel("Item Name");
private JLabel numberLabel = new JLabel("Number of units (or Volume in L)");
private JLabel priceLabel = new JLabel("Price per unit (Or L) in pence");
private JTextField nameField = new JTextField(10);
private JTextField numberField = new JTextField(10);
private JTextField priceField = new JTextField(10);
private JButton addVolumeButton = new JButton("Add by Volume");
private JButton addNumberButton = new JButton("Add by number of units");
public TestUI() {
JFrame frame = new JFrame("Fuel Station");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
outputArea.setEditable(false);
errorReportArea.setEditable(false);
inputPanel.setLayout(new BoxLayout(inputPanel, BoxLayout.X_AXIS));
inputPanel.add(nameLabel);
inputPanel.add(nameField);
inputPanel.add(numberLabel);
inputPanel.add(numberField);
inputPanel.add(priceLabel);
inputPanel.add(priceField);
inputPanel.add(addVolumeButton);
inputPanel.add(addNumberButton);
Container contentPane = frame.getContentPane();
contentPane.setLayout(new BoxLayout(contentPane, BoxLayout.Y_AXIS));
contentPane.add(outputArea);
contentPane.add(errorReportArea);
contentPane.add(inputPanel);
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
TestUI test1 = new TestUI();
}
}
Which looks like this:
So what I would like to do is set a specific size for the top two JTextFields, as the top one will contain multiple lines of text, and the one below will contain just one line of text. I am unsure how to do this without using setSize, as I have been told it is bad coding practice to use this.
I would also like to add some padding between the JLabels, JTextFields and JButtons in the bottom JPanel.
If anyone could give me some suggestions on resizing these components I would be most grateful

Since you want your textfields to be multilined, use JTextAreas. JTextFields are single lined only.
Your components are right next to each other which isn't the same look as your intended outcome. There may be some method that gives your components some breathing room before you would call frame.pack()
Look for any method that can make a component fill the total amount of room it's given; especially when you want something to fill a large chunk of space.
You can set the number of columns instead of using setSize() for your JTextFields/JTextAreas. Just saying.
Reviewing all of Java's Layout Managers would help you get a grasp of the capabilities and use cases for each layout manager

There are a few layout managers that are flexible enough to perform this, such as Mig, Gridbag, and SpringLayout.
In your case, you'd have the following constraints:
outputarea - south border constrained to be ###px from the north border of the contentPane
errorReportArea - north border constrained to be 0px from outputarea's south, and south border constrained to be 0px from inputPanel's north.
inputPanel - north border constrained to be ##px from the south border of the contentPane.
GUI builders such as WindowBuilder will allow you to do this pretty quickly. You just drop in the layout onto the contentPane and then set the constraints.

If you have to use a box layout look at the glue and rigidArea methods in Box. If you can use other layouts, go with those suggested by the other answers.

I have created a solution with the MigLayout manager.
Here are some recommendations:
Put application code outside the constructor; in the solution, the code
is placed in the initUI() method.
The application should be started on EDT by calling the
EventQueue.invokeLater(). (See the main() method of the provided solution.)
Use a modern, flexible layout manager: MigLayout, GroupLayout, or FormLayout.
Take some time to study them to fully understand the layout management process. It
is important have a good understanding of this topic.
Shorten the labels; use more descriptive tooltips
instead.
package com.zetcode;
import java.awt.EventQueue;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import net.miginfocom.swing.MigLayout;
public class MigLayoutSolution extends JFrame {
private JTextArea outputArea;
private JTextField errorReportField;
private JLabel nameLabel;
private JLabel numberLabel;
private JLabel priceLabel;
private JTextField nameField;
private JTextField numberField;
private JTextField priceField;
private JButton addVolumeButton;
private JButton addNumberButton;
public MigLayoutSolution() {
initUI();
}
private void initUI() {
setLayout(new MigLayout());
outputArea = new JTextArea(10, 20);
errorReportField = new JTextField(15);
nameLabel = new JLabel("Item name");
numberLabel = new JLabel("# of units");
numberLabel.setToolTipText("Number of units (or Volume in L)");
priceLabel = new JLabel("Price per unit");
priceLabel.setToolTipText("Price per unit (Or L) in pence");
nameField = new JTextField(10);
numberField = new JTextField(10);
priceField = new JTextField(10);
addVolumeButton = new JButton("AddVol");
addVolumeButton.setToolTipText("Add by Volume");
addNumberButton = new JButton("AddNum");
addNumberButton.setToolTipText("Add by number of units");
add(new JScrollPane(outputArea), "grow, push, wrap");
add(errorReportField, "growx, wrap");
add(nameLabel, "split");
add(nameField);
add(numberLabel);
add(numberField);
add(priceLabel);
add(priceField);
add(addVolumeButton);
add(addNumberButton);
pack();
setTitle("Fuel station");
setLocationRelativeTo(null);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
MigLayoutSolution ex = new MigLayoutSolution();
ex.setVisible(true);
}
});
}
}

JLabel alignment in JPanel

I'm trying to align a JLabel to the right in a JPanel. I'm adding a JTabbedPane, a JPanel which contains my JLabel and JTextArea to a main JPanel.
I have searched SO and tried some methods like setAlignmentX, setHorizontalAlignment(SwingConstants.LEFT) and nested containers to no avail.
Here's my code:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
class LabelProblem
{
public static void main(String[] args)
{
JFrame frame = new JFrame("Label Problem");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel Main = new JPanel();
Main.setLayout(new BoxLayout(Main, BoxLayout.Y_AXIS));
JPanel ComponentPanel = new JPanel();
JLabel label = new JLabel("Sample Text");
label.setHorizontalAlignment(SwingConstants.LEFT);
label.setBorder(BorderFactory.createLineBorder(Color.BLACK));
label.setAlignmentX(Component.RIGHT_ALIGNMENT);
ComponentPanel.add(label);
JTabbedPane Tab = new JTabbedPane();
Tab.add("Document 1", new JPanel());
Main.add(Tab);
Main.add(ComponentPanel);
JTextArea Area = new JTextArea(10,10);
JScrollPane Scroll = new JScrollPane(Area);
frame.add(Main);
frame.add(Scroll, BorderLayout.SOUTH);
frame.setSize(450,450);
frame.setVisible(true);
}
}
How can I align my JLabel to the right?
Thanks!

So, the place of that label is determined by the layout of ComponentPanel. Since you didn't specify any layout it is using the default FlowLayout with a CENTER alignment. Assuming that you are ok with a FlowLayout it is a mere question of setting the alignment of the LEFT since this is possible with this layout.
Here's the code with the fix, however I suspect that as you put more elements to the ComponentPanel you will want to use another layout since FlowLayout is more adequate for menus and the like and not for displaying the main content.
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Component;
import java.awt.FlowLayout;
import javax.swing.BorderFactory;
import javax.swing.BoxLayout;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTabbedPane;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;
class LabelProblem
{
public static void main(String[] args)
{
SwingUtilities.invokeLater(new Runnable()
{
public void run()
{
initGUI();
}
});
}
public static void initGUI()
{
JFrame frame = new JFrame("Label Problem");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel main = new JPanel();
main.setLayout(new BoxLayout(main, BoxLayout.Y_AXIS));
JPanel componentPanel = new JPanel(new FlowLayout(FlowLayout.LEFT));
JLabel label = new JLabel("Sample Text");
label.setBorder(BorderFactory.createLineBorder(Color.BLACK));
componentPanel.add(label);
JTabbedPane Tab = new JTabbedPane();
Tab.add("Document 1", new JPanel());
main.add(Tab);
main.add(componentPanel);
JTextArea area = new JTextArea(10, 10);
JScrollPane scroll = new JScrollPane(area);
frame.add(main);
frame.add(scroll, BorderLayout.SOUTH);
frame.setSize(450, 450);
frame.setVisible(true);
}
}
Result:
Note: I also changed the variable names to follow the java style convention: variable names should start with lower case to differenciate them from clases names, starting in upper case.

One simple approach is to set the label's horizontalAlignment to JLabel.RIGHT in the constructor.
import java.awt.*;
import javax.swing.*;
class LabelProblem {
public static void main(String[] args) {
JFrame frame = new JFrame("Label Problem");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new GridLayout(0, 1));
JTabbedPane tab = new JTabbedPane();
tab.add("Document 1", new JPanel());
frame.add(tab);
JLabel label = new JLabel("Sample Text", JLabel.RIGHT);
frame.add(label);
JTextArea area = new JTextArea(10, 10);
JScrollPane scroll = new JScrollPane(area);
frame.add(scroll);
frame.pack();
frame.setSize(450, 450);
frame.setVisible(true);
}
}

I think it may be a matter of you not actually setting layouts where you imagine you're setting layouts.
You have a JPanel with a vertically oriented BoxLayout (Main) enclosing another JPanel with default layout (ComponentPanel), finally enclosing your label. The reason why your label can't be pushed to the right is because is already is pushed to the right within it's enclosing container. If you set a colored border around ComponentPanel, you'll see what I mean -- it only occupies the same amount of space as the JLabel, giving the JLabel nowhere to move.
You need to set a layout and constraints for your intermediate ComponentPanel, allowing it to horizontally fill its parent container so that the label has someplace to go.
You haven't really specified how your layout is supposed to look, but if you change the layout on Main to X_AXIS, your label will pop over to the left (as will its parent container). Without knowing what you're really trying to do, I can't say much more.
I would however, suggest you throw your BoxLayout away entirely and look into using GridBagLayout, which gives you a high level control over your UI. GridBagLayout isn't the most concise construct, but that's the price of control.

JPanel with BoxLayout and ScrollPane as its Parent

I have a JScrollPane (with both scrollbars optional (should not cause the problem)
Inside of the ScrollPane is a panel with BoxLayout and X_Axis - align. (it contains arbitrary number of Panels with fixed (prefference)Size.
The Problem is that the ScrollPane will be much wider than necessary (Horizontal Scrollbar scrolls through "grey screen").
With Y_Axis align it works as it should.
Relevant code:
final JPanel forSpecific = new JPanel();
final JScrollPane scrollSpecific = new JScrollPane(forSpecific,
ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED,
ScrollPaneConstants.HORIZONTAL_SCROLLBAR_AS_NEEDED);
forSpecific.setLayout(new BoxLayout(forSpecific,BoxLayout.X_AXIS));
I have no idea whats the poblem and did not find any solution...
EDITED: sry it took some time. The original code was to complex to extract some sscce.. i wrote a test-class. This example works coorect.. but i dont know whats different.. package getdata;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.GridLayout;
import javax.swing.BoxLayout;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
public class Sscce {
public static void gui(){
final JFrame rootframe = new JFrame("Time Series Mining");
final JPanel mainPanel = new JPanel(new BorderLayout());
rootframe.setSize(new Dimension(400,400));
rootframe.setContentPane(mainPanel);
mainPanel.setLayout(new BorderLayout());
JPanel center=new JPanel(new GridLayout(2,1));
JPanel forSpecific=new JPanel();
forSpecific.setLayout(new BoxLayout(forSpecific, BoxLayout.X_AXIS));
JPanel test1 = new JPanel();
test1.setPreferredSize(new Dimension(1000,1000));
forSpecific.add(test1);
test1.setBackground(Color.white);
final JScrollPane scrollSpecific = new JScrollPane(forSpecific);
center.add(scrollSpecific);
rootframe.add(center, BorderLayout.CENTER);
rootframe.setVisible(true);
}
}

//final JScrollPane scrollSpecific = new JScrollPane(forSpecific,
// ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED,
// ScrollPaneConstants.HORIZONTAL_SCROLLBAR_AS_NEEDED);
final JScrollPane scrollSpecific = new JScrollPane(forSpecific);
Not the problem but the "scrollbar as needed" is the default. You don't need to specify this.
Inside of the ScrollPane is a panel with BoxLayout and X_Axis - align. (it contains arbitrary number of Panels with fixed (prefference)Size.
What is a fixed size?
the "main" panel added to the scrollpane
the "child" panels added to the main panel
In any case the size should not be fixed, the layout manager should determine the preferred size. Or if you are creating a custom component then you should override the getPreferredSize() method to return the proper size so the layout manager can do its job.