Develop Reference

Retain GridBagLayout component order?

I have problems with GridBagLayout. I have to replace a component but after inserting the new one the positions change. See the following code as example.
At the start it is CYAN and YELLOW (from left to the right). After replacing it is YELLOW and RED. My desired result is RED and YELLOW. How can I fix this (with GridBagLayout)?
import java.awt.Color;
import java.awt.Dimension;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class GBLTest extends JFrame
{
public static void main(String [] args)
{
new GBLTest();
}
JPanel panelA;
JPanel panelB;
JPanel panelAReplacement;
GBLTest()
{
this.setLayout(new GridBagLayout());
GridBagConstraints cons = new GridBagConstraints();
cons.weightx = 1.0;
cons.weighty = 1.0;
cons.fill = GridBagConstraints.BOTH;
panelA = new JPanel();
panelA.setBackground(Color.CYAN);
panelB = new JPanel();
panelB.setBackground(Color.YELLOW);
panelAReplacement = new JPanel();
panelAReplacement.setBackground(Color.RED);
cons.anchor = GridBagConstraints.EAST;
this.add(panelA, cons);
cons.anchor = GridBagConstraints.WEST;
this.add(panelB, cons);
GridBagConstraints oldCons = ((GridBagLayout) this.getContentPane().getLayout()).getConstraints(panelA);
this.remove(panelA);
this.add(panelAReplacement, oldCons);
this.setSize(new Dimension(200, 200));
this.setLocationRelativeTo(null);
this.setDefaultCloseOperation(EXIT_ON_CLOSE);
this.setVisible(true);
}
}

I think you are not using the correct Layout for this pourpose.
You should use BorderLayout instead GridBagLayout. Or use the gridx and gridy properties to set the cell where each panel should be allocated.
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class GBLTest extends JFrame
{
public static void main(String [] args)
{
new GBLTest();
}
JPanel panelA;
JPanel panelB;
JPanel panelAReplacement;
GBLTest()
{
this.setLayout(new GridBagLayout());
GridBagConstraints consA = new GridBagConstraints();
consA.weightx = 1.0;
consA.weighty = 1.0;
consA.fill = GridBagConstraints.BOTH;
consA.gridx = 0;
consA.gridy = 0;
GridBagConstraints consB = new GridBagConstraints();
consB.weightx = 1.0;
consB.weighty = 1.0;
consB.fill = GridBagConstraints.BOTH;
consB.gridx = 1;
consB.gridy = 0;
panelA = new JPanel();
panelA.setBackground(Color.CYAN);
panelB = new JPanel();
panelB.setBackground(Color.YELLOW);
panelAReplacement = new JPanel();
panelAReplacement.setBackground(Color.RED);
consA.anchor = GridBagConstraints.EAST;
this.add(panelA, consA);
consA.anchor = GridBagConstraints.WEST;
this.add(panelB, consB);
GridBagConstraints oldCons = ((GridBagLayout) this.getContentPane().getLayout()).getConstraints(panelA);
this.remove(panelA);
this.add(panelAReplacement, oldCons);
this.setSize(new Dimension(200, 200));
this.setLocationRelativeTo(null);
this.setDefaultCloseOperation(EXIT_ON_CLOSE);
this.setVisible(true);
}
}

GUI: JButton Covering almost the entire screen

I have encountered a problem whilst working the JFrame's, and JButtons. I am trying to center my JButton, however when I do so, it covers almost the entire screen. Any idea's on what's causing this?
Here is a picture on how it looks :
And here is my code :
package character;
import javax.imageio.ImageIO;
import javax.swing.*;
import java.awt.*;
import java.io.IOException;
/**
* Created by Niknea on 6/28/14.
*/
public class characterSelector{
JFrame cselectorButtons, clogo;
JLabel logo, characterName, label;
JButton male, female;
public characterSelector(){
this.createCharacterSelector();
}
public void createCharacterSelector() {
try {
label = new JLabel(new ImageIcon(ImageIO.read(getClass()
.getResource("/resources/Grass_Background.jpg"))));
cselectorButtons = new JFrame("SupremeSoccer");
logo = new JLabel(new ImageIcon(ImageIO.read(this.getClass().getResource("/resources/Character_Selector_Image.png"))));
characterName = new JLabel("<Character Name>");
characterName.setFont(new Font(characterName.getFont().getName(),
Font.HANGING_BASELINE, 50));
/*
Buttons
*/
male = new JButton("Male");
////******************////
//// END OF BUTTONS ////
////****************////
cselectorButtons.add(logo);
cselectorButtons.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
cselectorButtons.setContentPane(label);
cselectorButtons.setLayout(new BorderLayout());
cselectorButtons.add(logo, BorderLayout.NORTH);
cselectorButtons.add(male, BorderLayout.CENTER);
cselectorButtons.pack();
cselectorButtons.setLocationRelativeTo(null);
cselectorButtons.setVisible(true);
} catch (IOException exp) {
exp.printStackTrace();
}
}
}
Thanks again.

Any idea's on what's causing this?
This is the default behaviour of BorderLayout. The component at the CENTER position will occupy the maximum amount of space the is available from the parent component, when the other (NORTH, SOUTH, EAST, WEST) positions have been taken into account
Depending on what you are trying to achieve you might consider creating another JPanel (set it's opaque state to false so it's transparent) and use something like GridLayout or GridBagLayout instead.
Take a look at A Visual Guide to Layout Managers for some more ideas
Updated
So based on your linked code, I changed
part2 = new JPanel();
to
part2 = new JPanel(new java.awt.GridBagLayout());
And got...
Updated with additional example
Start by breaking down your requirements into individual containers and focus on the layout requirements for each individual, then build them all back into a single container.
This will make changing them later much easier and also make controlling them much easier...
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.awt.image.BufferedImage;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class ExampleLayout {
public static void main(String[] args) {
new ExampleLayout();
}
public ExampleLayout() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private HeaderPane header;
private ScorePane score;
private CharacterSelectionPane characterSelection;
public TestPane() {
setLayout(new BorderLayout());
JLabel background = new JLabel();
try {
BufferedImage img = ImageIO.read(getClass().getResource("/Grass.jpg"));
background.setIcon(new ImageIcon(img));
} catch (IOException ex) {
ex.printStackTrace();
}
add(background);
background.setLayout(new GridBagLayout());
header = new HeaderPane();
score = new ScorePane();
characterSelection = new CharacterSelectionPane();
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridwidth = GridBagConstraints.REMAINDER;
gbc.weightx = 1;
gbc.fill = GridBagConstraints.BOTH;
background.add(header, gbc);
background.add(score, gbc);
gbc.weighty = 1;
background.add(characterSelection, gbc);
}
}
public class HeaderPane extends JPanel {
public HeaderPane() {
setLayout(new BorderLayout());
JLabel label = new JLabel("Character Selection");
label.setForeground(Color.WHITE);
label.setFont(label.getFont().deriveFont(Font.BOLD, 48f));
label.setHorizontalAlignment(JLabel.CENTER);
add(label);
setOpaque(false);
}
}
public class ScorePane extends JPanel {
public ScorePane() {
JLabel label = new JLabel("[-][-[]-][-]");
label.setForeground(Color.YELLOW);
add(label);
setOpaque(false);
}
}
public class CharacterSelectionPane extends JPanel {
private JButton btMale;
private JButton btFemale;
private JTextField tfName;
private JButton btContinue;
public CharacterSelectionPane() {
setOpaque(false);
setLayout(new GridBagLayout());
btMale = new JButton("Male");
btFemale = new JButton("Female");
btContinue = new JButton("Continue");
tfName = new JTextField(10);
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridx = 0;
gbc.gridy = 0;
gbc.insets = new Insets(4, 4, 4, 4);
gbc.fill = GridBagConstraints.HORIZONTAL;
add(btMale, gbc);
gbc.gridx++;
add(btFemale, gbc);
gbc.gridx = 0;
gbc.gridy++;
add(new JLabel("Name:"), gbc);
gbc.gridx++;
add(tfName, gbc);
gbc.gridx = 0;
gbc.gridy++;
gbc.gridwidth = GridBagConstraints.REMAINDER;
add(btContinue, gbc);
}
}
}

Use a BoxLayout or (easier) GridBagLayout for the bottom area, as seen in this answer.

What's the best way to organize JPanels in a list?

I've found myself writing up quite a few programs recently which all need to display some collection of data. So far the best looking approach I've thought of is make small JPanels which contain data on each item in the collection and put them all in a big JPanel which I then put in a JScrollPane. It works and looks just as intended but there's one issue: I can't seem to get the smaller JPanels to start at the top of the bigger JPanel.
The problem is only apparent when I've got a small number of small JPanels (green) added into the bigger JPanel (red).
Described below is the method I used to produce the above and I'd like to know if there's a better way I could do it (where the list starts at the top like it should):
I created a class which extends JPanel and in it add all data I want to display. We'll call it "SmallPanel.java". I don't set the size of it (that comes later).
In my main window's class (which extends JFrame):
private JScrollPane scrollPane;
private JPanel panel;
...
scrollPane = new JScrollPane();
getContentPane().add(scrollPane);
panel = new JPanel();
panel.setLayout(new GridBagLayout());
scrollPane.setViewportView(panel);
...
private void addPanel()
{
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridx = 0;
gbc.gridy = panel.getComponentCount(); //The new JPanel's place in the list
gbc.fill = GridBagConstraints.HORIZONTAL;
gbc.anchor = GridBagConstraints.PAGE_START; //I thought this would do it
gbc.ipady = 130; //Set the panel's height, the width will get set to that of the container JPanel (which is what I want since I'd like my JFrames to be resizable)
gbc.insets = new Insets(2, 0, 2, 0); //Separation between JPanels in the list
gbc.weightx = 1.0;
SmallPanel smallPanel = new SmallPanel();
panel.add(smallPanel, gbc);
panel.revalidate();
panel.invalidate();
panel.repaint(); //Better safe than peeved
}
Call the addPanel() method every time I want to add a panel.
EDIT
Final solution (based on MadProgrammer's answer below):
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.border.BevelBorder;
public class ListPanel extends JPanel
{
private static final long serialVersionUID = 1L;
private JPanel fillerPanel;
private ArrayList<JPanel> panels;
public ListPanel(List<JPanel> panels, int height)
{
this(panels, height, new Insets(2, 0, 2, 0));
}
public ListPanel(List<JPanel> panels, int height, Insets insets)
{
this();
for (JPanel panel : panels)
addPanel(panel, height, insets);
}
public ListPanel()
{
super();
this.fillerPanel = new JPanel();
this.fillerPanel.setMinimumSize(new Dimension(0, 0));
this.panels = new ArrayList<JPanel>();
setLayout(new GridBagLayout());
}
public void addPanel(JPanel p, int height)
{
addPanel(p, height, new Insets(2, 0, 2, 0));
}
public void addPanel(JPanel p, int height, Insets insets)
{
super.remove(fillerPanel);
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridx = 0;
gbc.gridy = getComponentCount();
gbc.fill = GridBagConstraints.HORIZONTAL;
gbc.anchor = GridBagConstraints.PAGE_START;
gbc.ipady = height;
gbc.insets = insets;
gbc.weightx = 1.0;
panels.add(p);
add(p, gbc);
gbc = new GridBagConstraints();
gbc.gridx = 0;
gbc.gridy = getComponentCount();
gbc.fill = GridBagConstraints.VERTICAL;
gbc.weighty = 1.0;
add(fillerPanel, gbc);
revalidate();
invalidate();
repaint();
}
public void removePanel(JPanel p)
{
removePanel(panels.indexOf(p));
}
public void removePanel(int i)
{
super.remove(i);
panels.remove(i);
revalidate();
invalidate();
repaint();
}
public ArrayList<JPanel> getPanels()
{
return this.panels;
}
public static void main(String[] args)
{
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setMinimumSize(new Dimension(500, 500));
f.setLocationRelativeTo(null);
f.getContentPane().setLayout(new BorderLayout());
final ListPanel listPanel = new ListPanel();
for (int i = 1; i <= 10; i++)
listPanel.addPanel(getRandomJPanel(), new Random().nextInt(50) + 50);
JButton btnAdd = new JButton("Add");
btnAdd.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent paramActionEvent)
{
listPanel.addPanel(getRandomJPanel(), new Random().nextInt(50) + 50);
}
});
JButton btnRemove = new JButton("Remove");
btnRemove.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent paramActionEvent)
{
listPanel.removePanel(0);
}
});
f.getContentPane().add(btnRemove, BorderLayout.NORTH);
f.getContentPane().add(btnAdd, BorderLayout.SOUTH);
JScrollPane scrollPane = new JScrollPane();
scrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);
scrollPane.setViewportView(listPanel);
f.getContentPane().add(scrollPane, BorderLayout.CENTER);
f.setVisible(true);
}
public static JPanel getRandomJPanel()
{
JPanel panel = new JPanel();
panel.setBorder(new BevelBorder(BevelBorder.LOWERED, null, null, null, null));
panel.add(new JLabel("This is a randomly sized JPanel"));
panel.setBackground(new Color(new Random().nextFloat(), new Random().nextFloat(), new Random().nextFloat()));
return panel;
}
}

The best solution I've found is to use VerticalLayout from the SwingLabs SwingX (which can be downloaded from here) libraries.
You "could" use a GridBagLayout with an invisible component positioned at the end, whose weighty property is set to 1, but this is a lot more additional work to manage, as you need to keep updating the x/y positions of all the components to keep it in place...
Updated with GridBagLayout example
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class VerticalLayoutExample {
public static void main(String[] args) {
new VerticalLayoutExample();
}
public VerticalLayoutExample() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
final TestPane pane = new TestPane();
JButton add = new JButton("Add");
add.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
pane.addAnotherPane();
}
});
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new JScrollPane(pane));
frame.add(add, BorderLayout.SOUTH);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private JPanel filler;
private int y = 0;
public TestPane() {
setBackground(Color.RED);
setLayout(new GridBagLayout());
filler = new JPanel();
filler.setOpaque(false);
GridBagConstraints gbc = new GridBagConstraints();
gbc.weighty = 1;
gbc.gridy = 0;
add(filler, gbc);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 400);
}
public void addAnotherPane() {
JPanel panel = new JPanel(new GridBagLayout());
panel.add(new JLabel("Hello"));
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridy = y++;
gbc.weightx = 1;
gbc.fill = GridBagConstraints.HORIZONTAL;
gbc.gridwidth = GridBagConstraints.REMAINDER;
gbc.insets = new Insets(4, 4, 4, 4);
add(panel, gbc);
GridBagLayout gbl = ((GridBagLayout)getLayout());
gbc = gbl.getConstraints(filler);
gbc.gridy = y++;
gbl.setConstraints(filler, gbc);
revalidate();
repaint();
}
}
}
This is just a concept. As camickr has pointed out, so long as you know the last component, you can adjust the GridBagConstraints of the component so that the last component which is in the list has the weighty of 1 instead...
As you can, you can override some of the things GridBagLayout does, for example, instead of using the preferred size of the panel, I've asked GridBagLayout to make it fill the HORIZONTAL width of the parent container...

You can use a vertical BoxLayout.
Just make sure the maximum size of the panel is equal to the preferred size so the panel doesn't grow.
Edit:
Since your class already has a custom panel all you need to do is override the getMaximumSize() method to return an appropriate value. Something like:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.*;
public class VerticalLayoutExample2 {
public static void main(String[] args) {
new VerticalLayoutExample2();
}
public VerticalLayoutExample2() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
final TestPane pane = new TestPane();
JButton add = new JButton("Add");
add.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
pane.addAnotherPane();
}
});
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new JScrollPane(pane));
frame.add(add, BorderLayout.SOUTH);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private JPanel filler;
private int y = 0;
public TestPane() {
setBackground(Color.RED);
setLayout(new GridBagLayout());
setLayout(new BoxLayout(this, BoxLayout.Y_AXIS));
setBorder( new EmptyBorder(4, 4, 4, 4) );
}
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 400);
}
public void addAnotherPane() {
SmallPanel panel = new SmallPanel();
panel.setLayout( new GridBagLayout() );
panel.add(new JLabel("Hello"));
add(panel);
add(Box.createVerticalStrut(4));
revalidate();
repaint();
}
}
static class SmallPanel extends JPanel
{
#Override
public Dimension getMaximumSize()
{
Dimension preferred = super.getPreferredSize();
Dimension maximum = super.getMaximumSize();
maximum.height = preferred.height;
return maximum;
}
}
}
I know you mentioned you don't want to use a lib, but you can also look at Relative Layout. It is only a single class. It can easily mimic a BoxLayout but is easier to use because you don't need to override the getMaximumSize() method or add a Box component to the panel to give the vertical spacing.
You would set it as the layout of your panel as follow:
RelativeLayout rl = new RelativeLayout(RelativeLayout.Y_AXIS);
rl.setFill( true ); // fills components horizontally
rl.setGap(4); // vertical gap between panels
yourPanel.setLayout(rl);
yourPanel.add( new SmallPanel(...) );
yourPanel.add( new SmallPanel(...) );

Can't change size of block in BorderLayout

I created simple app with Border Layout and added into it two buttons and JTable. I use JSplitPane between button2 and JTable. I would like redefine default size of block where is situated button1. How can I to solve this task?
Here is my code:
package test;
import java.awt.BorderLayout;
import java.awt.Dimension;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JSplitPane;
import javax.swing.JTable;
import javax.swing.SwingUtilities;
public class Sample {
public Sample() {
JFrame app = new JFrame("Sample");
app.setSize(new Dimension(800,600));
JPanel panel = new JPanel();
app.add(panel);
BorderLayout borderlayout = new BorderLayout();
panel.setLayout(borderlayout);
JButton but1 = new JButton("1");
JButton but2 = new JButton("2");
but2.setMinimumSize(new Dimension(250,0));
String[] colNames = {"Name","Number","Scores"};
Object[][] data = {
{ "Mark",11,12},
{"Tommy",23,34},
{"John",34,45}
};
JTable table = new JTable(data, colNames);
JScrollPane scrollpane = new JScrollPane(table);
JSplitPane jsplitpane = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT,but2,scrollpane);
panel.add(but1,BorderLayout.NORTH);
panel.add(jsplitpane,BorderLayout.CENTER);
app.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
new Sample();
}
});
}
}

Components in the BorderLayout.PAGE_START location have the height of their preferred sizes respected. Therefore, you can override the preferred size of JButton but1
JButton but1 = new JButton("1") {
public Dimension getPreferredSize() {
return new Dimension(100, 80);
};
};

If you are willing to use GridBagLayout for the said purpose, then I guess this Layout and do this job for you, as stated in the below pasted code example :-)
import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Dimension;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JSplitPane;
import javax.swing.JTable;
import javax.swing.SwingUtilities;
public class Sample {
public Sample() {
JFrame app = new JFrame("Sample");
app.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
app.setSize(new Dimension(800,600));
JPanel panel = new JPanel();
panel.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
panel.setLayout(new BorderLayout(5, 5));
JPanel centerPanel = new JPanel();
centerPanel.setLayout(new GridBagLayout());
JButton but1 = new JButton("1");
JButton but2 = new JButton("2");
but2.setMinimumSize(new Dimension(250,0));
String[] colNames = {"Name","Number","Scores"};
Object[][] data = {
{ "Mark",11,12},
{"Tommy",23,34},
{"John",34,45}
};
JTable table = new JTable(data, colNames);
JScrollPane scrollpane = new JScrollPane(table);
JSplitPane jsplitpane = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT,but2,scrollpane);
GridBagConstraints gbc = new GridBagConstraints();
gbc.anchor = GridBagConstraints.FIRST_LINE_START;
gbc.fill = GridBagConstraints.BOTH;
gbc.gridx = 0;
gbc.gridy = 0;
gbc.weightx = 1.0;
gbc.weighty = 0.3;
centerPanel.add(but1, gbc);
gbc.fill = GridBagConstraints.BOTH;
gbc.gridy = 1;
gbc.weighty = 0.7;
centerPanel.add(jsplitpane, gbc);
panel.add(centerPanel, BorderLayout.CENTER);
app.add(panel);
app.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
new Sample();
}
});
}
}
Here is the output of the same :

Alignment issues with BoxLayout

I am making an application for which I am using a BoxLayout. As you can see in the following picture, when the title string is short, it's perfect. But as the string gets longer, the JLabel gets more and more misaligned.
Here's some code that is related to the problem:
JPanel centerPanel = new JPanel();
centerPanel.setLayout(new BoxLayout(centerPanel, BoxLayout.PAGE_AXIS));
frame.add(centerPanel, BorderLayout.CENTER);
//...
JLabel l = new JLabel(/*...*/);
l.setHorizontalAlignment(SwingConstants.CENTER); //I tried removing and adding
//this but nothing changed
centerPanel.add(l);
Is there something obvious I am missing? Google isn't being helpful with this problem.
In case it's important, the country-label-progress-bar things are just JPanels with FlowLayouts.
SSCCE:
import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
public class SSCCE {
public static void main(String[] args) {
final JFrame f = new JFrame("SSCCE");
JPanel p = new JPanel();
p.setLayout(new BoxLayout(p, BoxLayout.PAGE_AXIS));
final JLabel[] titles = new JLabel[5];
JPanel[] smallPanels = new JPanel[titles.length];
for (int i = 0; i < smallPanels.length; i ++) {
titles[i] = new JLabel(Math.random() < 0.5 ? "foo" : "bar");
p.add(titles[i]);
smallPanels[i] = new JPanel();
smallPanels[i].add(new JLabel("foobar"));
smallPanels[i].add(new JProgressBar());
p.add(smallPanels[i]);
}
f.add(p, BorderLayout.CENTER);
final JTextField tf = new JTextField("foobar");
tf.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
titles[2].setText(tf.getText());
f.repaint();
}
});
f.add(tf, BorderLayout.NORTH);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setSize(600, 600);
f.setVisible(true);
}
}
To operate the SSCCE, type something in the text field and press enter.

Here is an updated version of your SSCCE with a GridBagLayout. Not sure of how you want components to resize when labels or frame size changes but it should not be too hard to manage this.
import java.awt.BorderLayout;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Random;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JProgressBar;
import javax.swing.JTextField;
public class SSCCE {
public static void main(String[] args) {
final JFrame f = new JFrame("SSCCE");
JPanel p = new JPanel();
p.setLayout(new GridBagLayout());
Insets insets = new Insets(3, 3, 3, 3);
GridBagConstraints gbc1 = new GridBagConstraints();
gbc1.gridwidth = GridBagConstraints.REMAINDER;
gbc1.anchor = GridBagConstraints.CENTER;
gbc1.insets = insets;
GridBagConstraints gbc2 = new GridBagConstraints();
gbc2.anchor = GridBagConstraints.EAST;
gbc2.insets = insets;
GridBagConstraints gbc3 = new GridBagConstraints();
gbc3.weightx = 1.0;
gbc3.fill = GridBagConstraints.HORIZONTAL;
gbc3.gridwidth = GridBagConstraints.REMAINDER;
gbc3.insets = insets;
final JLabel[] titles = new JLabel[5];
Random random = new Random();
for (int i = 0; i < titles.length; i++) {
titles[i] = new JLabel(Math.random() < 0.5 ? "foo" : "bar");
p.add(titles[i], gbc1);
p.add(new JLabel("foobar"), gbc2);
JProgressBar progress = new JProgressBar();
progress.setStringPainted(true);
progress.setString(String.valueOf(random.nextInt(100)));
p.add(progress, gbc3);
}
f.add(p, BorderLayout.CENTER);
final JTextField tf = new JTextField("foobar");
tf.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
titles[2].setText(tf.getText());
f.repaint();
}
});
f.add(tf, BorderLayout.NORTH);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.pack();
f.setVisible(true);
}
}

BoxLayout accepting Min, Max and PreferredSize, childs could be resizable from Min to MaxSize
FlowLayout accepting only PreferredSize, rest (Min, MaxSize) is ignored by this LayoutManager, childs aren't resizable
these XxxSize are calculated from PreferredSize came from childs placed into container (JPanel in this case)
(your question) for better help sooner post an SSCCE, short, runnable, compilable, just about your issue