I'm trying to implement a feature that (in my test project) once a button is pressed, it adds a random number to my JPanel. (I use the layouts I have because in my real program, I have more items inside and it displays correctly). But I need my program to recognize when the scrollbar is visible (which I implemented that, but it's a little delay. What I mean by delay is I push the button to add a number, if the scrollbar becomes visible nothing happens. But then the next time I press the button it shifts over like I want). The other problem I have (the one I'm focused on now) is that when I dynamically change the size of the JPanel, if the scrollbar is visible, I have it set to change the width to my width - the width of the scrollbar. But It seems like when the scrollbar is visible, the newly inputted number moves over twice the scrollbar width instead of just once. I've been at this part of my program for over a day and can't figure it out. I'll add my full code and some screenshots.
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;
import java.util.Random;
import javax.swing.BorderFactory;
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.UIManager;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
public class Main {
JFrame frame;
JPanel topPanel;
JPanel memoryPanel;
JScrollPane sPane;
JButton button;
ArrayList<Integer> list = new ArrayList<>();
boolean isVScrollVisible = false;
int scrollBarSize = 0;
public class MyChangeListener implements ChangeListener {
#Override
public void stateChanged(ChangeEvent e) {
isVScrollVisible = (sPane.getVerticalScrollBar().isVisible());
}
}
public class ButtonListener implements ActionListener {
#Override
public void actionPerformed(ActionEvent e) {
Random random = new Random();
int r = random.nextInt(10);
list.add(r);
int n;
if (isVScrollVisible) {
n = scrollBarSize;
} else {
n = 0;
}
JPanel nextPanel = new JPanel();
nextPanel.setName("" + r);
nextPanel.setForeground(Color.BLACK);
nextPanel.setPreferredSize(new Dimension(200 - n, 55));
nextPanel.setMinimumSize(new Dimension(200 - n, 55));
nextPanel.setMaximumSize(new Dimension(200 - n, 55));
JPanel labelPanel = new JPanel();
labelPanel.setLayout(new BorderLayout());
JLabel label = new JLabel();
label.setText("" + r);
label.setPreferredSize(new Dimension(200 - n, 55));
label.setMinimumSize(new Dimension(200 - n, 55));
label.setMaximumSize(new Dimension(200 - n, 55));
label.setHorizontalAlignment(JLabel.RIGHT);
label.setBorder(BorderFactory.createEmptyBorder(0, 0, 0, 17));
label.setFont(new Font("Sans-Serif", Font.BOLD, 20));
labelPanel.add(label);
nextPanel.add(labelPanel, BorderLayout.LINE_START);
for (int i = 0; i < memoryPanel.getComponents().length; i++) {
memoryPanel.getComponent(i).setPreferredSize(new Dimension(200 - n, 55));
memoryPanel.getComponent(i).revalidate();
memoryPanel.getComponent(i).repaint();
}
memoryPanel.add(nextPanel, 0);
memoryPanel.revalidate();
memoryPanel.repaint();
sPane.revalidate();
sPane.repaint();
}
}
public Main() {
frame = new JFrame();
topPanel = new JPanel();
memoryPanel = new JPanel();
memoryPanel.setLayout(new BoxLayout(memoryPanel, BoxLayout.Y_AXIS));
sPane = new JScrollPane(memoryPanel, JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED, JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
sPane.setPreferredSize(new Dimension(200, 300));
sPane.getViewport().addChangeListener(new MyChangeListener());
scrollBarSize = ((Integer)UIManager.get("ScrollBar.width")) + 1;
button = new JButton("Add Random Number");
button.addActionListener(new ButtonListener());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
topPanel.add(button);
frame.add(topPanel, BorderLayout.PAGE_START);
frame.add(sPane, BorderLayout.CENTER);
frame.setResizable(false);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
new Main();
}
}
I need them to look exactly the same. Before I had the code I have now, the scrollbar would appear over the numbers which looked ugly. And the reason I have the frame resizable false is because In my real program I hard coded all the sizes, which in the future I will calculate the correct sizes based on the size of the frame, so right now setting resizable to true is out of the question. Any suggestions on what to do?
This is what I'm trying to accompolish.
Get rid of all the logic that sets the preferred/minimum/maximum sizes. Each component knows what its size should be. Each layout manager will in turn know what the preferred size of the panel should be. Let the layout manager use the information to do its job.
The basic logic for dynamically adding components is:
panel.add(...);
panel.revalidate();
panel.repaint();
Then the scrollbars will appear automatically when required. There is no need for listeners or anything.
Edit:
The reason I set all the sizes is because If I take them out then everything appears centered
Learn how to use layout managers properly and effectively.
For example when using a BoxLayout you can control the alignment of components by using:
component.setAlignmentX(JLabel.RIGHT_ALIGNMENT);
and the component will be aligned to the right edge of the space available to the component.
When using a JLabel you may also need to set a property on the JLabel to align the text to the right edge of the label. Read the JLabel API for the appropriate method.
Related
I'm having issues with my code regarding the fact that when I instantiate my City class as an object and add it to the right side of my JSplitPane (or even the left), the circle that is supposed to be drawn is not showing up. My cities class uses paintComponent and should draw a circle just by calling the constructor. I have also tried putting the repaint in its own drawIt() method but the result is still the same. The buttons and spinner show up on the left side of the divider, but the circle I am trying to draw does not show up at all.
Here is my City class.
import javax.swing.*;
import java.awt.*;
public class City extends JPanel{
int xPos, yPos;
City(int x, int y){
xPos = x;
yPos = y;
repaint();
}
public void paintComponent(Graphics g){
super.paintComponent(g);
g.setColor(Color.BLACK);
g.fillOval(xPos, yPos, 10, 10);
}
}
And here is my main.
Here I try to instantiate my city and add it to the right side of the JSplitPane (under Add Components) and that is where I am having issues with, as the black circle will not be drawn on the JSplitPane.
import java.awt.*;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JSpinner;
import javax.swing.JSplitPane;
import javax.swing.SpinnerNumberModel;
import javax.swing.SwingUtilities;
public class TSP{
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new TSP();
}
});
}
TSP(){
JLabel instructions = new JLabel("Enter the number of cities: ");
instructions.setBounds(30, 150, 300, 40);
SpinnerNumberModel numMod = new SpinnerNumberModel(2, 2, 10, 1);
JSpinner numOfCities = new JSpinner(numMod);
numOfCities.setBounds(185, 150, 80, 40);
JButton start = new JButton("Start Simulation");
start.setBounds(50, 400, 200, 40);
JFrame frame = new JFrame("Travelling Salesperson");
JSplitPane sp = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT);
JPanel lp = new JPanel(null);
JPanel rp = new JPanel(null);
sp.setDividerLocation(300);
sp.setLeftComponent(lp);
sp.setRightComponent(rp);
sp.setEnabled(false);
frame.setDefaultCloseOperation(3);
frame.setSize(1100,600);
frame.setResizable(false);
////////////////Add Components//////////////////////////
lp.add(instructions);
lp.add(numOfCities);
lp.add(start);
City test = new City(301, 301);
rp.add(test);
frame.add(sp);
////////////////////////////////////////////////////////
frame.setVisible(true);
}
}
I feel like the circle is being drawn under the JSplitPane as if I add my cities object (test) to my frame instead of the JSplitPane(frame.add(test) instead of rp.add(test) under the Add Components section) the black circle will appear in the desired spot but the JSplitPane along with the buttons and spinners will disappear so I feel as if they are conflicting. Is there any fix to this or is there another way altogether to make the circle appear on the right side while the other components are on the left side.
I do not know why it is not drawing the circle on the JSplitPane, but any sort of help would be appreciated. Thanks!
Sorry if anything is unclear or there is any ambiguity in my code, or if I need to post more information as I am quite new to posting here. Let me know if there is anything else I need to add or if there are any questions regarding what I am asking!
EDIT:
It seems there is something blocking where I draw the circle, like another JPanel. Here is an image below. As you can see part of the circle looks as if it is being covered. The small box I drew is the only area that the dot is visible from (everywhere else the circle is covered up by white). Also, the coordinates for the circle in the image below is at (3, 0), i.e City test = new City(3, 0);
I am not quite sure why this is happening though.
the invisible JPanel?
Now that I've seen what you're trying to do, I can provide a more proper answer.
You have a control panel on the left and a drawing panel on the right. Usually, you don't use a JSplitPane to separate the panels. To create your layout, you would add the control panel to the LINE_START of the JFrame BorderLayout and the drawing panel to the CENTER.
The reason for this is that you don't want to constantly recalculate the size of the drawing panel.
So let me show you one way to get a solid start. Here's the GUI I created.
Here are the things I did.
All Swing GUI applications must start with a call to the SwingUtilities invokeLater method. This method ensures that Swing components are created and executed on the Event Dispatch Thread.
I separated the creation of the JFrame, the control panel, and the drawing panel. That way, I could focus on one part of the GUI at a time.
The JFrame methods must be called in a certain order. This is the order that I use for most of my Swing applications.
The JFrame is not sized. It is packed. The Swing layout managers will calculate the size of the components and the JPanels.
I used a FlowLayout and a GridBagLayout to create the control panel. Yes, this looks more complicated than absolute positioning, but in the long run, layout managers allow the GUI to be more flexible.
I used the setPreferredSize method in the drawing panel to set the preferred size of the drawing panel. Because I know the drawing panel size, I can put the first city in the center of the drawing panel.
And here's the code. You don't have to code exactly like this, but this code should give you a good basis to start your project. Take a look at the model / view / controller pattern and see how to further separate your code into smaller pieces that allow you to focus on one part of your application at a time.
I put all the classes in one file to make it easier to paste. You should separate these classes into separate files.
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JSpinner;
import javax.swing.SpinnerNumberModel;
import javax.swing.SwingUtilities;
public class CitySimulation implements Runnable {
public static void main(String[] args) {
SwingUtilities.invokeLater(new CitySimulation());
}
private ControlPanel controlPanel;
private DrawingPanel drawingPanel;
private JFrame frame;
#Override
public void run() {
frame = new JFrame("Traveling Salesperson");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
controlPanel = new ControlPanel();
frame.add(controlPanel.getPanel(), BorderLayout.LINE_START);
drawingPanel = new DrawingPanel();
frame.add(drawingPanel, BorderLayout.CENTER);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public class ControlPanel {
private JPanel panel;
public ControlPanel() {
panel = new JPanel(new FlowLayout());
JPanel mainPanel = new JPanel(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.anchor = GridBagConstraints.LINE_START;
gbc.fill = GridBagConstraints.HORIZONTAL;
gbc.gridx = 0;
gbc.gridy = 0;
gbc.insets = new Insets(10, 10, 10, 10);
JLabel instructions = new JLabel("Enter the number " +
"of cities:");
mainPanel.add(instructions, gbc);
gbc.gridx++;
gbc.insets = new Insets(10, 0, 10, 10);
SpinnerNumberModel numMod =
new SpinnerNumberModel(2, 2, 10, 1);
JSpinner numOfCities = new JSpinner(numMod);
mainPanel.add(numOfCities, gbc);
gbc.anchor = GridBagConstraints.CENTER;
gbc.gridx = 0;
gbc.gridy++;
gbc.gridwidth = 2;
gbc.insets = new Insets(10, 10, 10, 10);
JButton start = new JButton("Start Simulation");
mainPanel.add(start, gbc);
panel.add(mainPanel);
}
public JPanel getPanel() {
return panel;
}
}
public class DrawingPanel extends JPanel {
private static final long serialVersionUID = 1L;
public DrawingPanel() {
this.setBackground(Color.WHITE);
this.setPreferredSize(new Dimension(400, 400));
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(Color.BLACK);
g.fillOval(195, 195, 10, 10);
}
}
}
So I have been trying to come up with a good layout manager that will enable me to put multiple components in a scrollable panel with different sizes. The only one I found was gridlayout, but it forces the same size.
here is the current code I have:
package main;
import java.awt.Dimension;
import java.awt.GridLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Main {
public static void main(String[] args) {
// Create and set up a frame window
JFrame frame = new JFrame("Layout");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// Define the panel to hold the components
JPanel panel = new JPanel(new GridLayout(0, 1, 0, 0));
panel.setPreferredSize(new Dimension(500, 800));
for (int i = 0; i < 20; i++) {
JButton button = new JButton("Button " + i);
button.setPreferredSize(new Dimension(50, 100 + (i * 10)));
panel.add(button);
}
// Add the panel and set the window to be visible
frame.add(panel);
frame.pack();
frame.setVisible(true);
}
}
I also do know about GridBagLayout, but I do want a layout that wouldn't require me to enter the numbers manually.
I also do know about GridBagLayout, but I do want a layout that wouldn't require me to enter the numbers manually.
You can specify:
constraint.gridWidth = GridBagConstraints.REMAINDER;
and each component will be placed on a new row.
Or you can use a BoxLayout, as I suggested in my comment, and not worry about constraints.
Read the tutorial. The constraints for the GridBagLayout are explained in more detail.
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
I built a great GUI using the frowned upon null layout (I defined a lot of constants and used a window resize listener to make it easy). Everything worked perfectly until I started using a new computer. Now, the component's are not positioned properly (from the picture you can see that the components are offset down and right). After researching the problem I learned that layout managers make sure that the components are positioned properly throughout different machines. Because of this, I would like to start rebuilding the GUI in an actual layout manager. The problem is that I often feel limited in the way I position components when attempting to use an actual layout manager.
For anyone who is curious, I was originally using a dell inspiron laptop with windows 10, and have moved to an Asus Laptop (I don't know the actual model, but the touch screen can detach from the keyboard), also with windows 10.
My question:
Which layout manager would be the fastest and easiest to build the GUI shown in the picture above (out of the stock Swing Layouts and others). I would like this layout to respect the components' actual sizes for only a few but not all of the components. Using this layout, how would I go about positioning the inventory button (the hammer at the bottom left) so that the bottom left corner of the inventory button is 5 pixels up and right from the bottom left corner of the container, even after resizing the container?
Thanks in advance. All help is appreciated.
EDIT: The "go find a key" and "Attempt to force the door open" options should have their sizes respected.
The simplest solution that comes to my mind is a BorderLayout for the main panel. Add the textarea to NORTH / PAGE_START. Make another BorderLayout containing the inventory button (WEST / LINE_START) and the location label (EAST / LINE_END). Add that to SOUTH / PAGE_END of the main BorderLayout. Then just add a BoxLayout with vertical alignment to the main BorderLayout's CENTER containing the two buttons. Here's a tutorial for the standard layout managers.
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Insets;
import java.awt.image.BufferedImage;
import javax.swing.BorderFactory;
import javax.swing.Box;
import javax.swing.BoxLayout;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextArea;
public class Example {
public Example() {
JTextArea textArea = new JTextArea("There is a locked door");
textArea.setRows(5);
textArea.setBorder(BorderFactory.createLineBorder(Color.GRAY));
textArea.setEditable(false);
WhiteButton button1 = new WhiteButton("Go find a key") {
#Override
public Dimension getMinimumSize() {
return new Dimension(200, 25);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 25);
}
#Override
public Dimension getMaximumSize() {
return new Dimension(200, 25);
}
};
WhiteButton button2 = new WhiteButton("Attempt to force the door open");
button2.setMargin(new Insets(0, 60, 0, 60));
JPanel buttonPanel = new JPanel();
buttonPanel.setLayout(new BoxLayout(buttonPanel, BoxLayout.Y_AXIS));
buttonPanel.add(button1);
buttonPanel.add(Box.createVerticalStrut(5));
buttonPanel.add(button2);
WhiteButton inventoryButton = new WhiteButton(
new ImageIcon(new BufferedImage(50, 50, BufferedImage.TYPE_INT_RGB)));
JLabel locationLabel = new JLabel("Location: 0");
locationLabel.setVerticalAlignment(JLabel.BOTTOM);
JPanel southPanel = new JPanel(new BorderLayout());
southPanel.add(inventoryButton, BorderLayout.WEST);
southPanel.add(locationLabel, BorderLayout.EAST);
JPanel mainPanel = new JPanel(new BorderLayout(0, 5));
mainPanel.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
mainPanel.add(textArea, BorderLayout.NORTH);
mainPanel.add(buttonPanel);
mainPanel.add(southPanel, BorderLayout.SOUTH);
JFrame frame = new JFrame("Example");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setContentPane(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
new Example();
}
});
}
private class WhiteButton extends JButton {
public WhiteButton() {
setBackground(Color.WHITE);
}
public WhiteButton(String text) {
this();
setText(text);
}
public WhiteButton(ImageIcon icon) {
this();
setIcon(icon);
setBorder(BorderFactory.createLineBorder(Color.GRAY));
}
}
}
I am trying to create very simple class. The goal is to create a button in the maximum size when scrollbars are not visible yet. My code doesn`t work. The condition pane.getVerticalScrollBar().isVisible() returns true even if the scrollbar is not visible. I wonder why and how can I fix it?
import java.awt.BorderLayout;
import java.io.UnsupportedEncodingException;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
public class Main {
public static void main(String[] args) throws UnsupportedEncodingException {
JFrame frame = new JFrame();
final JButton button = new JButton("Hello");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel panel = new JPanel(new BorderLayout());
final JPanel buttons = new JPanel();
buttons.add(button);
buttons.revalidate();
final JScrollPane pane = new JScrollPane(buttons);
pane.getViewport().addChangeListener(new ChangeListener() {
#Override
public void stateChanged(ChangeEvent e) {
System.out.println("*******************************************************************");
System.out.println("Vertical visible? " + pane.getVerticalScrollBar().isVisible());
System.out.println("Horizontal visible? " + pane.getHorizontalScrollBar().isVisible());
if (!pane.getVerticalScrollBar().isVisible() && !pane.getHorizontalScrollBar().isVisible()) {
button.setSize(button.getWidth() + 1, button.getHeight() + 1);
buttons.revalidate();
pane.revalidate();
} else {
button.setSize(button.getWidth() - 1, button.getHeight() - 1);
buttons.revalidate();
pane.revalidate();
pane.getViewport().removeChangeListener(this);
}
}
});
panel.add(pane);
frame.setContentPane(panel);
frame.setSize(300, 200);
frame.setVisible(true);
}
}
Don't play with the set size method.
If you want the button to occupy all the space available then use either:
frame.add(button); // height/width will be max
frame.add(button, BorderLayout.SOUTH); // only width will be max
Let the layout managers do the job for you.
Edit:
I have another class which scale img in the label and I want to find the best value for scale to make it maximalized as possible
Create a custom panel and dynamically draw the image at the size of the panel. Then it will automatically scale based on the space available.
See Background Panel as an example of this approach.