Develop Reference

JSplitPane -- can't set maximum size;

Been a while since I've been here. I'm learning java and have a question as to why the panel I've created in a JSplitPane can be resized beyond the maximum that I've set:
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class MainWindow {
//set all components
JFrame frame;
JPanel showPanel;//displays individual contact when clicked on in the contacts panel;
JPanel listPanel;// displays the contactsPanel
JSplitPane contactsSplitPane;
public void buildMainWindow() {// open method
frame = new JFrame("Contacts");
frame.setBackground(Color.WHITE);
frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
showPanel = new JPanel();
showPanel.setBackground(Color.WHITE);
listPanel = new JPanel();
listPanel.setBackground(Color.LIGHT_GRAY);
listPanel.setMaximumSize(new Dimension (300,1000));
//create SplitPane for the listPanel and showPanel
contactsSplitPane = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, listPanel,showPanel);
contactsSplitPane.setOneTouchExpandable(true);
contactsSplitPane.setDividerLocation(50);
frame.setSize(1000, 1000);
frame.setVisible(true);
frame.add(BorderLayout.CENTER, contactsSplitPane);
}//close method
public static void main (String [] args) {
MainWindow MainWindow = new MainWindow ();
MainWindow.buildMainWindow();
}
}// close class
feel free to run and compile. I've set the size of the listPanel to a maximum of 300 pixels, but I can resize it way beyond that -- almost to the end of the frame. It's not possible to crate a single resizable pane, no?
Can someone let me know what I'm doing wrong? I'm obviously missing something, but I don't know what.

A JSplitPane doesn't respect the maximum size of either component.
However, it does respect the minimum size of a component.
So one approach could be do set the minimum size on the other component added to the split pane. You will need to override the getMinimumSize() method of this component since the size of the split pane can change dynamically.
Something like:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class SplitPaneMaximum extends JPanel
{
JSplitPane splitPane;
public SplitPaneMaximum()
{
setLayout( new BorderLayout() );
JPanel red = new JPanel();
red.setBackground( Color.RED );
red.setPreferredSize( new Dimension(200, 100) );
red.setMinimumSize( new Dimension(100, 0) );
JPanel blue = new JPanel()
{
// Setting a minimum size here will limit the maximum size
// of the other component added to the split pane
#Override
public Dimension getMinimumSize()
{
int parentWidth = getParent().getSize().width;
Dimension d = getSize();
d.width = parentWidth - 200;
return d;
}
};
blue.setBackground( Color.BLUE );
blue.setPreferredSize( new Dimension(200, 100) );
splitPane = new JSplitPane();
splitPane.setLeftComponent( red );
splitPane.setRightComponent( blue );
splitPane.setResizeWeight(0.50);
add(splitPane, BorderLayout.CENTER);
}
private static void createAndShowUI()
{
JFrame frame = new JFrame("SplitPaneMaximum");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add( new SplitPaneMaximum() );
frame.pack();
frame.setLocationRelativeTo( null );
frame.setVisible( true );
}
public static void main(String[] args)
{
EventQueue.invokeLater(new Runnable()
{
public void run()
{
createAndShowUI();
}
});
}
}
Now the width of the red panel can only be sized between 100 and 200 pixels.

Layout manager problems while programming UI

There is a specific UI that I am trying to create for a Java program and I have been having trouble choosing the adequate Layout Managers. I would like my program to have a top panel with three elements (Two JTextFields and one JButton) and a lower JPanel that has another JPanel inside. The inner panel should always be a square, centered according to its container and adapt to the maximum height or width of its container. I have tried using a ComponentAdapter to achieve the effect of always staying a square, but the program does not seem to act the way I want it to, also the top Panel seems to get squeezed to the top
JPanel maincontainer = new JPanel();
maincontainer.setLayout(new BoxLayout(maincontainer, BoxLayout.PAGE_AXIS));
JPanel jpanel2 = new JPanel();
jpanel2.setLayout(new GridLayout(0, 3));
JTextField txt = new JTextField();
txt.setFocusable(false);
JButton btn = new JButton();
btn.setFocusable(false);
JTextField txt2 = new JTextField();
txt2.setFocusable(false);
jpanel2.add(txt);
jpanel2.add(btn);
jpanel2.add(txt2);
maincontainer.add(jpanel2);
JPanel masterPane = new JPanel(new GridBagLayout());
JPanel centerPane = new JPanel();
masterPane.add(centerPane);
masterPane.addComponentListener(new ComponentAdapter() {
#Override
public void componentResized(ComponentEvent e) {
if(masterPane.getHeight()<masterPane.getWidth())
centerPane.setSize(masterPane.getHeight(), masterPane.getHeight());
else
centerPane.setSize(masterPane.getWidth(), masterPane.getWidth());
}
});
centerPane.setBackground(Color.blue);
masterPane.add(centerPane);
maincontainer.add(masterPane);
JFrame frame = new JFrame("");
frame.getContentPane().add(maincontainer);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setResizable(true);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
frame.setMinimumSize(new Dimension(300,300));
frame.setSize(500, 500);

I would like my program to have a top panel with three elements (Two JTextFields and one JButton) and a lower JPanel that has another JPanel inside.
The easiest way to do this is to keep using the default layout manager of the frame which is a BorderLayout. You add the panel with the text fields and buttons to the BorderLayout.PAGE_START. Then you add the panel that changes dynamically to the BorderLayout.CENTER.
The inner panel should always be a square, centered according to its container and adapt to the maximum height or width of its container
The easiest way to center a component on a panel is to use a GridBagLayout on the panel. The default GridBagConstraints will cause the component to be displayed at it preferred size centered both vertically and horizontally. So you will need a wrapper panel using the GridBagLayout to contain your center panel.
You would then want to override the getPreferredSize() method of your center panel to dynamically change as the size of the parent panel changes. This is a better approach than using a ComponentListener.
Something like:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
public class SSCCE extends JPanel
{
SSCCE()
{
setLayout( new BorderLayout() );
JPanel top = new JPanel( new GridLayout(0, 3) );
top.add( new JTextField(10) );
top.add( new JButton("Button") );
top.add( new JTextField(10) );
add(top, BorderLayout.PAGE_START);
JPanel center = new JPanel()
{
#Override
public Dimension getPreferredSize()
{
Dimension parent = getParent().getSize();
if (parent.width < parent.height)
return new Dimension(parent.width, parent.width);
else
return new Dimension(parent.height, parent.height);
}
};
center.setBackground( Color.BLUE );
JPanel wrapper = new JPanel( new GridBagLayout() );
wrapper.add(center, new GridBagConstraints());
add(wrapper, BorderLayout.CENTER);
}
private static void createAndShowGUI()
{
JFrame frame = new JFrame("SSCCE");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new SSCCE());
frame.pack();
frame.setLocationByPlatform( true );
frame.setVisible( true );
}
public static void main(String[] args)
{
EventQueue.invokeLater( () -> createAndShowGUI() );
/*
EventQueue.invokeLater(new Runnable()
{
public void run()
{
createAndShowGUI();
}
});
*/
}
static class DragListener extends MouseInputAdapter
{
Point location;
MouseEvent pressed;
public void mousePressed(MouseEvent me)
{
pressed = me;
}
public void mouseDragged(MouseEvent me)
{
Component component = me.getComponent();
location = component.getLocation(location);
int x = location.x - pressed.getX() + me.getX();
int y = location.y - pressed.getY() + me.getY();
component.setLocation(x, y);
}
}
}

How to move button to exact location?

I want the buttons and textfield to go in the spaces marked red in the same layout as they are in. look at the picture to understand what I mean.
update: the buttons are in the place now, but the image wont appear on the second panel
how can I move them to there? heres my code so far
package gasindicator;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import javax.swing.*;
import javax.swing.border.*;
import javax.swing.plaf.basic.*;
import java.io.*;
import javax.imageio.*;
import java.net.*;
public class GasIndicator extends JPanel
{
private Image image;
GasIndicator()
{
try
{
image = ImageIO.read(new URL("http://i68.tinypic.com/2ceja8i.png"));
}
catch (IOException ioe)
{
System.out.println("Unable to fetch image.");
ioe.printStackTrace();
}
setLayout( new BorderLayout() );
JLabel background = new JLabel( new ImageIcon(image) );
background.setLayout( new FlowLayout(FlowLayout.LEFT) );
add( background );
JPanel buttonPanel = new JPanel( new GridLayout(0, 3, 6, 5) );
buttonPanel.setBorder( new EmptyBorder(338, 233, 0, 0) );
buttonPanel.setOpaque( false );
//for (int i = 0; i < 7; i++)
{
JButton button = new JButton("Button");
JButton button1 = new JButton("Button");
JButton button2 = new JButton("Button");
JButton button3 = new JButton("Button");
JButton button4 = new JButton("Button");
JButton button5 = new JButton("Button");
button.setPreferredSize( new Dimension(160, 45) );
buttonPanel.add(button);
buttonPanel.add(button1);
buttonPanel.add(button2);
buttonPanel.add(button3);
buttonPanel.add(button4);
buttonPanel.add(button5);
button.addActionListener(new Action());
}
background.add( buttonPanel );
}
static class Action implements ActionListener {
public void actionPerformed(ActionEvent e) {
JFrame frame2 = new JFrame("Museums in London");
frame2.setVisible(true);
frame2.setSize(550, 650);
JPanel panel = new JPanel();
frame2.add(panel);
Custom contentPane;
// JFrame frame = new JFrame("JTextField");
contentPane = new Custom();
frame2.setContentPane(contentPane);
}
}
private static void ShowGUI()
{
JFrame frame = new JFrame("SSCCE");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new GasIndicator());
frame.pack();
frame.setLocationByPlatform( true );
frame.setVisible( true );
}
public static void main(String[] args)
{
EventQueue.invokeLater( () -> ShowGUI() );
/*
EventQueue.invokeLater(new Runnable()
{
public void run()
{
createAndShowGUI();
}
});
*/
}
class Custom extends JPanel {
public BufferedImage image;
public Custom() {
try {
image = ImageIO.read(new URL
("http://www.destination360.com/europe/uk/images/s/museums.jpg"));
} catch (IOException ioe) {
System.out.println("Unable to fetch image.");
ioe.printStackTrace();
}
}
public Dimension getPreferredSize() {
return (new Dimension(image.getWidth(), image.getHeight()));
}
public void paintComponent(Graphics x) {
super.paintComponent(x);
x.drawImage(image, 10, 10, this);
}
}
}

Simple example to demonstrate the concept of using a layout manager with a Border. The size of the buttons has also been tweaked to the size of the buttons in the image:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.*;
import javax.swing.plaf.basic.*;
import java.io.*;
import javax.imageio.*;
import java.net.*;
public class SSCCE extends JPanel
{
private Image image;
SSCCE()
{
try
{
image = ImageIO.read(new URL("http://i68.tinypic.com/2ceja8i.png"));
}
catch (IOException ioe)
{
System.out.println("Unable to fetch image.");
ioe.printStackTrace();
}
setLayout( new BorderLayout() );
JLabel background = new JLabel( new ImageIcon(image) );
background.setLayout( new FlowLayout(FlowLayout.LEFT) );
add( background );
JPanel buttonPanel = new JPanel( new GridLayout(0, 3, 6, 5) );
buttonPanel.setBorder( new EmptyBorder(338, 233, 0, 0) );
buttonPanel.setOpaque( false );
for (int i = 0; i < 6; i++)
{
JButton button = new JButton("Button " + i);
button.setPreferredSize( new Dimension(160, 45) );
buttonPanel.add(button);
}
background.add( buttonPanel );
}
private static void createAndShowGUI()
{
JFrame frame = new JFrame("SSCCE");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new SSCCE());
frame.pack();
frame.setLocationByPlatform( true );
frame.setVisible( true );
}
public static void main(String[] args)
{
EventQueue.invokeLater( () -> createAndShowGUI() );
/*
EventQueue.invokeLater(new Runnable()
{
public void run()
{
createAndShowGUI();
}
});
*/
}
}
Yes, there is still some tweaking of the values. But it is easier to adjust the location of the entire panel with one EmptyBorder and all the buttons move at the same time than it is to adjust the location of each button individually.
Note: Don't use the JLabel to display the image as the components will shift if the frame is resized. Instead use your custom panel to paint the image.

The problem here is that your panel has the standart Layoutmanager set onto it.
Try disable it with
contentPane.setLayout(null);
Then you can move the buttons around like you want with button.setBountds(x,y,w,h);
I always draw directly on the Frame, not using a custom panel like you do, but I see that there are use cases where this would be the better way.
If you write
new JFrame.getContentPane().setLayout(null);
your frame gets the default pane and still has it's layout set to null.
The difference is you can add directly to the frame instead of using a panel where you drop your stuff on.
frame.add(new Button().setBounds(x,y,w,h));
Try out this version of the code I tried to debugg:
Custom1 contentPane;
//at first create and set the frame
JFrame frame = new JFrame("Windowname goes here");
frame.setSize(1160, 700);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocationRelativeTo(null);
//next add your custom panel
contentPane = new Custom1();
frame.setContentPane(contentPane);
//better add this to the panel instead of the frame
JTextField textfield = new JTextField(20);
frame.add(textfield);
textfield.setBackground(Color.black);
textfield.setForeground(Color.white);
//you are using 2 panels with null layout here
JPanel panel = new JPanel();
panel.setSize(frame.getHeight(),frame.getWidth()); //give the panel some bounds!
panel.setOpaque(false); //unnecesary
panel.setLayout(null);
panel.setBackground(Color.BLACK);
frame.add(panel);
JButton button = new JButton("London");
JButton button1 = new JButton("Oxford");
JButton button2 = new JButton("Cambridge");
//you seemed to not have added these before
JButton button4 = new JButton("Click");
JButton button5 = new JButton("Click");
JButton button6 = new JButton("Click");
button.setBounds(60, 400, 220, 30);
button.setBackground(Color.black);
button.setForeground(Color.WHITE);
button1.setBounds(x,y,w,h); // !!!! <------
button1.setBackground(Color.black);
button1.setForeground(Color.WHITE);
button2.setBounds(x,y,w,h); // !!!! <------
button2.setBackground(Color.black);
button2.setForeground(Color.WHITE);
button4.setBounds(80, 50, 100, 30);
button5.setBounds(x,y,w,h); // !!!! <------
button6.setBounds(x,y,w,h); // !!!! <------
panel.add(button);
panel.add(button1);
panel.add(button2);
panel.add(button3);
panel.add(button4);
panel.add(button5);
panel.add(button6);
//SETVISIBLE ALWAYS GOES LAST
frame.setVisible(true);
I patched your code and wrote some comments in it.
I marked the spots where you need to set the bounds for the buttons with !!!!<----, you seemed to have made this for button4 but not for the other ones. Also you should get a better structure in your code, I don't want to insult you but I would call this "spaghetti code".
There are aswell some things that where a problem, for example you seemed to not have added the buttons at all but they where present in your picture...
Let me know if it would work or not after playing around with the bounds value and investigating for eventual mistakes in the code.
Also if you sent me the whole project I could watch over it, but better try it yourself, it won't give you anything if someone else made your work.
Good luck and happy coding ( ͡° ͜ʖ ͡°)

How would I position a JComponent to true center in a BorderLayout?

I am developing a Swing application using BorderLayout to position the components. Since BorderLayout.CENTER positions components to whatever is left after the other components are placed, and that fact is making my GUI look weird, I was wondering if there was a way to position components to true center, rather than in between the two sides. Since BorderLayout spaces make a component fill an entire space, I'm guessing the solution would be to wrap the component into a JPanel. However, positioning the component to the center of this panel will make the component be closer to one side than another if you have components on other sides. How do I work around this?
These images demonstrate the problem and the ideal solution; the gray border represents the BorderLayout.SOUTH (wrapped in a JPanel) of the main frame. The black squares represents components that are throwing the center component off. The red square represents the component that needs to be centered.
Problem:
Ideal solution:

As I see the problem, in order for the red component to be centered the right and left components must be of equal size.
You might be able to use the Relative Layout.
The RelativeLayout will allow you to make the right/left components the same size while keeping the center component at its preferred size. As the frame is resized space will be added/removed from the right/left components.
For example:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.text.*;
public class SSCCE extends JPanel
{
public SSCCE()
{
JPanel left = new JPanel( new FlowLayout(FlowLayout.LEFT) );
JPanel leftBox = new JPanel();
leftBox.setPreferredSize( new Dimension(200, 50) );
leftBox.setBackground( Color.BLACK );
left.add( leftBox );
JPanel center = new JPanel( new FlowLayout(FlowLayout.CENTER) );
JPanel centerBox = new JPanel();
centerBox.setPreferredSize( new Dimension(50, 50) );
centerBox.setBackground( Color.RED );
center.add( centerBox );
JPanel right = new JPanel( new FlowLayout(FlowLayout.RIGHT) );
JPanel rightBox = new JPanel();
rightBox.setPreferredSize( new Dimension(50, 50) );
rightBox.setBackground( Color.BLACK );
right.add( rightBox );
setLayout( new RelativeLayout(RelativeLayout.X_AXIS, 5) );
add(left, new Float(1));
add(center);
add(right, new Float(1));
}
private static void createAndShowGUI()
{
JFrame frame = new JFrame("SSCCE");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new SSCCE());
frame.setLocationByPlatform( true );
frame.pack();
frame.setVisible( true );
}
public static void main(String[] args)
{
EventQueue.invokeLater(new Runnable()
{
public void run()
{
createAndShowGUI();
}
});
}
}
The one problem with the relative layout is that when you pack the frame the components will be dislayed too small since the preferred size is simply the sum of the components. So the left panel will be truncated.
In the example above you can add the following to get around this problem:
right.add( rightBox );
right.setPreferredSize( left.getPreferredSize() ); // added
Another option might be to use the OverlayLayout which can be set up to display the red panel over top of a panel containing the two other components:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
public class SSCCE extends JPanel
{
public SSCCE()
{
JPanel left = new JPanel( new FlowLayout(FlowLayout.LEFT) );
JPanel leftBox = new JPanel();
leftBox.setPreferredSize( new Dimension(200, 50) );
leftBox.setBackground( Color.BLACK );
left.add( leftBox );
JPanel center = new JPanel( new FlowLayout(FlowLayout.CENTER) );
center.setOpaque(false);
JPanel centerBox = new JPanel();
centerBox.setPreferredSize( new Dimension(50, 50) );
centerBox.setBackground( Color.RED );
center.add( centerBox );
JPanel right = new JPanel( new FlowLayout(FlowLayout.RIGHT) );
JPanel rightBox = new JPanel();
rightBox.setPreferredSize( new Dimension(50, 50) );
rightBox.setBackground( Color.BLACK );
right.add( rightBox );
JPanel main = new JPanel( new BorderLayout() );
main.add(left, BorderLayout.LINE_START);
main.add(right, BorderLayout.LINE_END);
setLayout( new OverlayLayout(this) );
add(center);
add(main);
}
private static void createAndShowGUI()
{
JFrame frame = new JFrame("SSCCE");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new SSCCE());
frame.setLocationByPlatform( true );
frame.pack();
frame.setVisible( true );
}
public static void main(String[] args)
{
EventQueue.invokeLater(new Runnable()
{
public void run()
{
createAndShowGUI();
}
});
}
}

SetVisible(false) changes the layout of my components within my Panel

How do I make the subpanels within my main panel stay where they are when I set one of the subpanels to be invisible?
What I have looks like:
[ (Panel1) (Panel2) (Panel3) (Panel4) ]
When I do panel3.setVisible(false) it then looks like:
[ (Panel1) (Panel2) (Panel4) ]
I would like it to look like:
[ (Panel1) (Panel2) (Panel4) ]
I am using the GridBagLayout and my mainPanel declaration looks like:
final JPanel panel = new JPanel(new GridBagLayout());
GridBagConstraints c = new GridBagConstraints();
and I add an new panel like:
final JTextField valueTextField = new JTextField();
valueTextField.setPreferredSize(new Dimension(80, 25));
valueTextField.setName("Value");
c.gridx =0;
panel.add(valueTextField, c);
I'll provide more code if needed and I don't care which layout I use as long as it gets me what I want.

I suggest using a CardLayout within the individual cells, and instead of setting it to invisible, switch to an empty panel instead.
The code below demonstrates this. Within hidePanel() there are two options to hide the cell with the CardLayout route currently enabled.
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class InvisiblePanels {
public static void main(String... args) throws Exception {
JFrame frame = new JFrame();
frame.setLayout(new GridBagLayout());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
GridBagConstraints c = new GridBagConstraints();
c.gridx = 0;
frame.add(new MyPanel(), c);
c.gridx = 1;
frame.add(new MyPanel(), c);
c.gridx = 2;
frame.add(new MyPanel(), c);
frame.pack();
frame.setVisible(true);
}
private static class MyPanel extends JPanel {
CardLayout layout;
public MyPanel() {
layout = new CardLayout();
setLayout(layout);
JButton button = new JButton("Click me");
button.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
hidePanel();
}
});
add(button, "visible");
add(new JPanel(), "invisible");
layout.show(this, "visible");
}
public void hidePanel() {
// setVisible(false);
layout.show(this, "invisible");
}
}
}

I believe all the layout manager respect the visibility of a component and don't include invisible components in the preferred size and layout calculations.
One solution might be to wrap all your panels in a panel using the OverlayLayout:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class OverlayLayoutInvisible
{
public static void main(String[] args)
{
JPanel panel = new JPanel();
panel.add( createPanel("Button 1") );
panel.add( createPanel("Button 2") );
panel.add( createPanel("Button 3") );
panel.add( createPanel("Button 4") );
panel.add( createPanel("Button 5") );
JFrame frame = new JFrame();
frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
frame.add( panel );
frame.pack();
frame.setLocationRelativeTo( null );
frame.setVisible(true);
}
public static JPanel createPanel(String text)
{
JButton button = new JButton( text );
button.addActionListener( new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
Component c = (Component)e.getSource();
c.setVisible(false);
}
});
InvisibleComponent ic = new InvisibleComponent( button );
JPanel panel = new JPanel();
panel.setLayout( new OverlayLayout(panel) );
panel.add( ic );
panel.add( button );
return panel;
}
public static class InvisibleComponent extends JComponent
{
private Component master;
public InvisibleComponent(Component master)
{
this.master = master;
setAlignmentX( master.getAlignmentX() );
setAlignmentY( master.getAlignmentY() );
}
public Dimension getPreferredSize()
{
return master.getPreferredSize();
}
}
}

You might be able to tweak GridLayout (do you have an SSCCE?)
Otherwise:
Put Panel3 and Panel4 together in a single panel that you add to the GridBagLayout. Then setup the new Panel in a Layout like FlowLayout (aligned Left with a preferred size), BorderLayout, GridLayout, etc.