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Java Set Layout

I need to create a JFrame which has three JPanels laid out as shown:
Could anybody please tell me how I can achieve this layout? I have already tried using BorderLayout, but in BorderLayout, if I add the topmost pane at BorderLayout.NORTH, the one in the center at BorderLayout.CENTER, and the one at the bottom to BorderLayout.SOUTH, the topmost pane becomes too small (in height) and the pane in the center becomes too big (in height).
P.S. I have already made the 3 panes and set their preferred sizes properly.

You could use all sorts of things, compound layouts (using two BorderLayouts for example) or other layouts, it will depend on what you ultimately want to achieve.
For simplicity, I'd use a GridBagLayout, for example...
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class TestLayout {
public static void main(String[] args) {
new TestLayout();
}
public TestLayout() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
public TestPane() {
setLayout(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridwidth = GridBagConstraints.REMAINDER;
gbc.weightx = 1;
gbc.weighty = 1;
gbc.fill = GridBagConstraints.BOTH;
add(new ABigPanel(), gbc);
gbc.weighty = 0;
gbc.fill = GridBagConstraints.HORIZONTAL;
add(new ASmallPanel(), gbc);
add(new ASmallerPanel(), gbc);
}
}
public class ABigPanel extends JPanel {
public ABigPanel() {
setBackground(Color.RED);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(400, 200);
}
}
public class ASmallPanel extends JPanel {
public ASmallPanel() {
setBackground(Color.GREEN);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 180);
}
}
public class ASmallerPanel extends JPanel {
public ASmallerPanel() {
setBackground(Color.CYAN);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 40);
}
}
}
See How to Use GridBagLayout for more details

Center JLabel in BorderLayout with a button at line end

I have a header on a section of my swing layout, and I want to have text centered horizontally across the whole width of the section, but also have a button on only the right side. It should look like this:
/------Same width------\ /------Same width------\
[------------------------]Text here[----------------[Button]]
I am currently using a BorderLayout, with the text in the center and the button at the line end, but the text is centered not counting the button, as such:
/----Same width----\ /---Same width----\
[--------------------]Text here[-------------------][Button]]

I'm not sure if this is the answer you really want, but you could use a different layout manager, like GridBagLayout
import java.awt.EventQueue;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class JavaApplication295 {
public static void main(String[] args) {
new JavaApplication295();
}
public JavaApplication295() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
public TestPane() {
setLayout(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridx = 0;
gbc.gridy = 0;
// gbc.fill = GridBagConstraints.HORIZONTAL;
gbc.weightx = 1;
add(new JLabel("Look ma, no hands"), gbc);
gbc.anchor = GridBagConstraints.EAST;
add(new JButton("No Allowance"), gbc);
}
}
}
Now, the problem with this, is both components are actually positioned at the same location, the difference is, the button is anchored to the right position of the cell, this means that when the layout is been calculated, they will overlap....

Here is an approach using the OverlayLayout which was designed to have multiple components painted on the z axis:
import java.awt.*;
import javax.swing.*;
public class SSCCE extends JPanel
{
public SSCCE()
{
JLabel label = new JLabel("I'm a Centered Label");
Box labelBox= Box.createHorizontalBox();
labelBox.add(Box.createHorizontalGlue());
labelBox.add(label);
labelBox.add(Box.createHorizontalGlue());
JButton button = new JButton("Button");
Box buttonBox= Box.createHorizontalBox();
buttonBox.add(Box.createHorizontalGlue());
buttonBox.add(button);
setLayout( new OverlayLayout(this) );
add(buttonBox);
add(labelBox);
}
private static void createAndShowGUI()
{
JFrame frame = new JFrame("SSCCE");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new SSCCE(), BorderLayout.NORTH);
frame.setLocationByPlatform( true );
frame.pack();
frame.setVisible( true );
}
public static void main(String[] args)
{
EventQueue.invokeLater(new Runnable()
{
public void run()
{
createAndShowGUI();
}
});
}
}
As the width decreases the button will paint over the label.

Swing: How to create a scrollable list of JPanels that use no Layout

I am trying to find a way to create a list of JPanels which have no Layout manager.
I found several examples on SO providing solutions to the 'scrollable JPanel list' problem. More specifically, I started from this thread and worked on it.
My current problem is that I am having issues when I remove the layout from the JPanels in the list.
They get added correctly but the scrollbar does not appear when needed, and the panels start overlapping.
Note: I know that layouts are heavily preferred but I find it more straightforward to work with pure X, Y coordinates and a mockup program. Please do not bash me for this...
Here is a small working example (taken and modified from this comment):
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.border.MatteBorder;
public class JScrollPanels {
private int i;
private JPanel listContainer;
private void initUI() {
final JFrame frame = new JFrame(JScrollPanels.class.getSimpleName());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
listContainer = new JPanel();
listContainer.setLayout(new BoxLayout(listContainer, BoxLayout.Y_AXIS));
frame.add(new JScrollPane(listContainer), BorderLayout.CENTER);
JButton button = new JButton("Add");
button.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
final JPanel newPanel = new JPanel();
newPanel.setLayout(null);
newPanel.setSize(272, 110);
JLabel name = new JLabel("Name " + i++);
name.setBounds(18, 13, 84, 21);
newPanel.setBorder(new MatteBorder(0, 0, 1, 0, Color.GRAY));
JLabel date = new JLabel("12/11/2014");
date.setBounds(10, 44, 123, 21);
JButton btn= new JButton(">");
btn.addActionListener( new NameListener(name, date) );
btn.setBounds(205, 44, 48, 30);
newPanel.add(name);
newPanel.add(date);
newPanel.add(btn);
listContainer.add(newPanel);
listContainer.revalidate();
// Scroll down to last added panel
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
newPanel.scrollRectToVisible(newPanel.getBounds());
}
});
}
});
frame.add(button, BorderLayout.PAGE_END);
frame.setSize(272, 300);
frame.setVisible(true);
}
public static void main(String[] args) {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (InstantiationException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IllegalAccessException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (UnsupportedLookAndFeelException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new JScrollPanels().initUI();
}
});
}
public class NameListener implements ActionListener {
private JLabel name;
private JLabel date;
public NameListener(JLabel name, JLabel date) {
this.name = name;
this.date = date;
}
public void actionPerformed(ActionEvent e) {
System.out.println("Clicked " + name.getText() + " on " + date.getText());
}
}
}
EDIT:
Fixed by using this:
final JPanel newPanel = new JPanel(){
#Override
public Dimension getPreferredSize() {
return new Dimension(272, 110);
}
};
Thanks, mKorbel!

Again, I still persist in my claim that in the long run, a layout manager will work best. For instance, your GUI could use something perhaps like this:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.text.SimpleDateFormat;
import java.util.Date;
import javax.swing.*;
import javax.swing.border.Border;
#SuppressWarnings("serial")
public class JScrollPanels2 extends JPanel {
private static final int PREF_W = 300;
private static final int PREF_H = 300;
private int i;
private JPanel listContainer;
public JScrollPanels2() {
JPanel outerWrapperPanel = new JPanel(new BorderLayout());
listContainer = new JPanel();
listContainer.setLayout(new BoxLayout(listContainer, BoxLayout.Y_AXIS));
outerWrapperPanel.add(listContainer, BorderLayout.PAGE_START);
JPanel buttonPanel = new JPanel(new GridLayout(1, 0, 5, 0));
buttonPanel.add(new JButton(new AddAction("Add")));
setLayout(new BorderLayout());
add(new JScrollPane(outerWrapperPanel), BorderLayout.CENTER);
add(buttonPanel, BorderLayout.PAGE_END);
}
#Override
public Dimension getPreferredSize() {
if (isPreferredSizeSet()) {
return super.getPreferredSize();
}
return new Dimension(PREF_W, PREF_H);
}
private class AddAction extends AbstractAction {
public AddAction(String name) {
super(name);
int mnemonic = (int) name.charAt(0);
putValue(MNEMONIC_KEY, mnemonic);
}
#Override
public void actionPerformed(ActionEvent evt) {
listContainer.add(new CellPanel(i));
listContainer.revalidate();
listContainer.repaint();
i++;
}
}
private class CellPanel extends JPanel {
private final int gap = 4;
private int index;
private String name;
private Date date;
private final String format = "MM/dd/yyyy";
private SimpleDateFormat sdf = new SimpleDateFormat(format);
public CellPanel(int i) {
this.index = i;
this.name = "Name " + index;
setLayout(new GridBagLayout());
date = new Date();
Border emptyBorder = BorderFactory.createEmptyBorder(gap, gap, gap, gap);
Border lineBorder = BorderFactory.createLineBorder(Color.black);
setBorder(BorderFactory.createCompoundBorder(lineBorder, emptyBorder));
add(new JLabel(name), createGbc(0, 0));
add(new JLabel(""), createGbc(1, 0));
add(new JLabel(sdf.format(date)), createGbc(0, 1));
add(new JButton(new MyBtnAction(">")), createGbc(1, 1));
}
private GridBagConstraints createGbc(int x, int y) {
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridx = x;
gbc.gridy = y;
gbc.gridwidth = 1;
gbc.gridheight = 1;
gbc.weightx = 1.0;
gbc.weighty = 1.0;
if (x % 2 == 0) {
gbc.anchor = GridBagConstraints.WEST;
} else {
gbc.anchor = GridBagConstraints.EAST;
}
return gbc;
}
private class MyBtnAction extends AbstractAction {
public MyBtnAction(String name) {
super(name);
// int mnemonic = (int) name.charAt(0);
// putValue(MNEMONIC_KEY, mnemonic);
}
#Override
public void actionPerformed(ActionEvent evt) {
System.out.println("Button pressed for " + name);
}
}
}
private static void createAndShowGui() {
JScrollPanels2 mainPanel = new JScrollPanels2();
JFrame frame = new JFrame("JScrollPanels2");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
One of the beauties of use of layout managers is their flexibility. If you wanted to add new components to the inner JPanel, you can easily do so without having to manually recalculate every dang other component's position, if they need to be shifted. Instead, let the layout managers do the heavy lifting for you. Also, while your null-layout using GUI might look good on one platform it will usually look terrible on most other platforms or screen resolutions.

how to make JButton show a list of JButtons with just few items

Hey Guys my problem is when I place the mouse on a JButton in my JFrame, I want it to show a list of JButtons on its left.
I don't known how to do that really I feel like I'm blocked and I cant make any progress in my project.
I'd would be grateful if you could help me and thanks in advance.

Can you create the list of buttons in a JPanel, add it to your JFrame and then call myPanel.setVisible(false). When you click your button then call myPanel.setVisible(true)?
As for ensuring that myPanel is positioned correctly you will want to use a Layout Manager
Or is there a more complex behaviour you want?

A basic option would be to use a MouseListener and a CardLayout. The MouseListener would be used to determine when the mouse cursor enters/exists a given component and the CardLayout would be used to display the appropriate sub component for each "menu" element.
I have to say, JButton would be me last choice for the "menu" item, in most cases, a JLabel would be preferred or even perhaps using a JMenu, which can can have sub menus, which can be displayed automatically might be a better choice, or even a JComboBox....
import java.awt.BorderLayout;
import java.awt.CardLayout;
import java.awt.EventQueue;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class ShowStuff {
public static void main(String[] args) {
new ShowStuff();
}
public ShowStuff() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
MenuPane menu = new MenuPane();
menu.addMenu("Fruit", new FruitPane());
menu.addMenu("Meat", new MeatPane());
menu.addMenu("Dairy", new DairyPane());
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(menu);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class MenuPane extends JPanel {
private JPanel subMenu;
private JPanel menu;
private CardLayout cardLayout;
private MouseListener mouseHandler;
public MenuPane() {
setLayout(new BorderLayout());
cardLayout = new CardLayout();
subMenu = new JPanel(cardLayout);
menu = new JPanel(new GridBagLayout());
add(subMenu);
add(menu, BorderLayout.WEST);
subMenu.add(new JPanel(), "BLANK");
mouseHandler = new MouseAdapter() {
#Override
public void mouseEntered(MouseEvent e) {
if (e.getSource() instanceof JButton) {
JButton btn = (JButton) e.getSource();
cardLayout.show(subMenu, btn.getText());
}
}
#Override
public void mouseExited(MouseEvent e) {
cardLayout.show(subMenu, "BLANK");
}
};
}
public void addMenu(String name, JPanel subMenuPane) {
JButton button = new JButton(name);
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridwidth = GridBagConstraints.REMAINDER;
menu.add(button, gbc);
subMenu.add(subMenuPane, name);
button.addMouseListener(mouseHandler);
}
}
public abstract class ButtonPane extends JPanel {
private int gridy = 0;
public ButtonPane() {
setLayout(new GridBagLayout());
}
protected void addButton(String name) {
JButton btn = new JButton(name);
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridx = 0;
gbc.gridy = gridy++;
gbc.fill = GridBagConstraints.HORIZONTAL;
add(btn, gbc);
}
}
public class FruitPane extends ButtonPane {
public FruitPane() {
addButton("Banana");
addButton("Grapes");
addButton("Apples");
addButton("Tomatoes");
}
}
public class MeatPane extends ButtonPane {
public MeatPane() {
addButton("Lamb");
addButton("Beef");
addButton("Pork");
addButton("Mince");
}
}
public class DairyPane extends ButtonPane {
public DairyPane() {
addButton("Milk");
addButton("Cream");
addButton("Cheese");
addButton("Yoghurt");
}
}
}

Writing at the bottom of JTextArea

I have a JScrollPane and a JTextArea (editable) with 10 rows. I want the first user input to appear at the bottom of the JTextArea and the most recent input should push the previous input upward. To achieve this I use textArea.setMargin(new Insets(x,0,0,0)); and everything works as it should - except that my second input will toggle the JScrollPane.
How can I start at the bottom of the JTextArea and only enable scrolling when the entire original viewport is filled?

Basically, you could add the JTextText onto a JPanel with another JPanel which acts a filler, causing the JTextArea to occupy the smallest space it actually needs.
I did this by using GridBagLayout to force the fill to occupy the most of space it could...
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class TestTextArea {
public static void main(String[] args) {
new TestTextArea();
}
public TestTextArea() {
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 JScrollPane(new TestPane()));
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private JTextArea ta;
public TestPane() {
setLayout(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridx = 0;
gbc.gridy = 0;
gbc.weightx = 1;
gbc.weighty = 1;
gbc.fill = GridBagConstraints.BOTH;
JPanel filler = new JPanel();
filler.setBackground(Color.WHITE);
add(filler, gbc);
gbc.gridy = 1;
gbc.weighty = 0;
ta = new JTextArea(1, 20);
add(ta, gbc);
}
}
}

To achieve this I use textArea.setMargin(new Insets(x,0,0,0)); and everything works as it should - except that my second input will toggle the JScrollPane.
Well I would guess that you would need to reset the margin every time you add text to the text area to take into account the new preferred size of the text area in relation to the size of the scroll pane.
You should be able to add a DocumentListener to the text area and make your adjustment whenever text is added to the Document.

I don't think that using margins and insets is the way to go because you are using layout adjustments to achieve text (content) functionality. This should be controlled by the Document object, which is what JTextArea makes its calls to regarding its content.
If you are calling append internally, then override it in a new class extending JTextArea:
public class Test {
static MyTextArea ta = new MyTextArea();
static int x = 0;
public static void main(String[] args) {
ta.setRows(10);
ta.setText("\n\n\n\n\n\n\n\n\n");
ta.setCaretPosition(ta.getDocument().getLength());
JButton append = new JButton("Append");
append.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
ta.append("\n" + x);
x++;
}
});
JFrame frame= new JFrame();
frame.setContentPane(new JPanel(new BorderLayout()));
frame.getContentPane().add(new JScrollPane(ta), BorderLayout.CENTER);
frame.getContentPane().add(append, BorderLayout.LINE_START);
frame.pack();
frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
static class MyTextArea extends JTextArea {
#Override
public void append(String str) {
super.append(str);
try {
if (getDocument().getText(0, 1).equals("\n"))
getDocument().remove(0, 1);
} catch (BadLocationException e) {
e.printStackTrace();
}
}
}
}
If you are editing it manually, add a DocumentListener:
public class Test {
public static void main(String[] args) {
JTextArea ta = new JTextArea();
ta.setRows(10);
ta.setText("\n\n\n\n\n\n\n\n\n");
ta.setCaretPosition(ta.getDocument().getLength());
ta.getDocument().addDocumentListener(new MyDocListener());
JFrame frame= new JFrame();
frame.setContentPane(new JPanel(new BorderLayout()));
frame.getContentPane().add(new JScrollPane(ta), BorderLayout.CENTER);
frame.pack();
frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
static class MyDocListener implements DocumentListener {
#Override
public void insertUpdate(DocumentEvent e) {
final DocumentEvent de = e;
Runnable pushUp = new Runnable() {
#Override
public void run() {
String t = null;
try {
t = de.getDocument().getText(de.getOffset(), de.getLength());
if (t.equals("\n") && de.getDocument().getText(0, 1).equals("\n"))
ta.getDocument().remove(0, 1);
} catch (BadLocationException e1) {
e1.printStackTrace();
}
}
};
SwingUtilities.invokeLater(pushUp);
}
#Override
public void removeUpdate(DocumentEvent e) {}
#Override
public void changedUpdate(DocumentEvent e) {}
}
}
Note that all you need from the code are the inner classes, the rest is just so you can see it working. I also don't have information regarding the initial state of the text area. Here I just set the number of rows to 10 and the text to 10 empty lines. I'm also not sure what you're allowed to do in the text area. This solution assumes that you can't jump lines and each time you insert a line it's not blank and it follows the previous line.