I have a frame which contains a vertical toolbar with a combobox and some buttons. The combobox takes up the maximum height it can in the toolbar. Why? And how to solve this? Is there a way to fix the size of the combobox?
The code:
import java.awt.BorderLayout;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JToolBar;
import javax.swing.border.BevelBorder;
public class Clipping extends JPanel {
public Clipping()
{
setLayout(new BorderLayout());
JToolBar toolbar = new JToolBar(JToolBar.VERTICAL);
CreateToolBarButtons(toolbar);
toolbar.setFloatable(false);
toolbar.setBorder(new BevelBorder(BevelBorder.RAISED));
add(toolbar, BorderLayout.WEST);
}
private static void CreateToolBarButtons(JToolBar toolbar)
{
String[] cboList = {"Line", "Polygon"};
JComboBox cboDraw = new JComboBox(cboList);
JButton btnClip = new JButton("Set clip area");
JButton btnClear = new JButton("Clear");
toolbar.add(cboDraw);
toolbar.addSeparator();
toolbar.add(btnClip);
toolbar.addSeparator();
toolbar.add(btnClear);
}
public static void main(String[] args)
{
CreateFrame();
}
private static void CreateFrame()
{
JFrame frame = new JFrame("Clipping");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new Clipping());
frame.setSize(500,500);
frame.setVisible(true);
}
}
JToolbar uses a BoxLayout and JComboBox has an issue with it. See this question for a solution. Rather than creating a subclass, try to just setMaximumSize on the combo box with the height that you like.
Related
This question already has answers here:
Java GUI: How to Set Focus on JButton in JPanel on JFrame?
(5 answers)
Closed 4 years ago.
The following program shows a JTextArea and a "Close" JButton. I defined the button as the default button because I would like it to have the focus as soon as I open the window. However, when I run the program the button is highlighted but the focus is on the text field.
How do I set the focus on the button and not the text area?
package test;
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.ScrollPaneConstants;
import javax.swing.border.EtchedBorder;
public class Test {
static JPanel southPanel;
static JButton closeButton;
static JFrame frame;
static JTextArea textArea;
private static final Dimension REASON_AREA_SIZE = new Dimension(250, 50);
public static void main(String args[]) {
String title = "";
frame = new JFrame();
frame.setLayout(new BorderLayout());
frame.setSize(1000, 800);
textArea = new JTextArea();
textArea.setLineWrap(true);
textArea.setWrapStyleWord(true);
textArea.setEditable(true);
JScrollPane lScrollPane = new JScrollPane(textArea);
lScrollPane.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED);
lScrollPane.setPreferredSize(REASON_AREA_SIZE);
frame.add(lScrollPane, BorderLayout.CENTER);
frame.add(createSouthPanel(), BorderLayout.SOUTH);
//Here the close button is defined by default, the focus should be on it
setDefaultButton();
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.setTitle(title);
frame.setVisible(true);
}
private static JPanel createSouthPanel() {
southPanel = new JPanel(
new FlowLayout(FlowLayout.RIGHT, 10, 10));
southPanel.setBorder(new EtchedBorder(EtchedBorder.RAISED));
addCloseButton(southPanel);
return southPanel;
}
/**
* Set the close button as default
*/
protected static void setDefaultButton() {
frame.getRootPane().setDefaultButton(closeButton);
}
private static void addCloseButton(JPanel pButtonsPanel) {
closeButton = new JButton("Close");
closeButton.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent pEvent) {
frame.dispose();
}
});
pButtonsPanel.add(closeButton);
}
}
Inside your setDefaultButton() method, add:
closeButton.requestFocus()
Focus is different to the default.
I failed to change the height of JPanel or JScrollPane to make more lines to appear, I used GridLayout. It seems that, every component in it should have the same size even when I use setSize(). Should I use another layout?
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextField;
public class Main {
private JFrame mainFrame;
private JLabel headerLabel;
private JLabel statusLabel;
private JPanel controlPanel;
private imagePanel image;
JTextField textField = new JTextField(20);
public Main() throws IOException{
prepareGUI();
}
class imagePanel extends JPanel {
private static final long serialVersionUID = 1L;
public void paint(Graphics g) {
try {
BufferedImage image = ImageIO.read(new File("file.jpg"));
g.drawImage(image, 170, 0, null);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
public static void main(String[] args) throws IOException{
Main swingControlDemo = new Main();
swingControlDemo.showEventDemo();
}
private void prepareGUI(){
mainFrame = new JFrame("Java SWING Examples");
mainFrame.setSize(400,500);
GridLayout gridlayout = new GridLayout(4, 1);
gridlayout.setVgap(1);
mainFrame.setLayout(gridlayout);
headerLabel = new JLabel("",JLabel.CENTER );
statusLabel = new JLabel("",JLabel.CENTER);
JScrollPane scroller = new JScrollPane(statusLabel, JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED, JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
mainFrame.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent windowEvent){
System.exit(0);
}
});
controlPanel = new JPanel();
controlPanel.setLayout(new FlowLayout());
image = new imagePanel();
image.setLayout(new FlowLayout());
// mainFrame.add(headerLabel);
mainFrame.add(image);
mainFrame.add(controlPanel);
mainFrame.add(scroller);
mainFrame.setVisible(true);
}
private void showEventDemo(){
headerLabel.setText("Control in action: Button");
JButton okButton = new JButton("reload");
JButton submitButton = new JButton("Submit");
JButton cancelButton = new JButton("Cancel");
okButton.setActionCommand("reload");
submitButton.setActionCommand("Submit");
cancelButton.setActionCommand("Cancel");
okButton.addActionListener(new ButtonClickListener());
submitButton.addActionListener(new ButtonClickListener());
cancelButton.addActionListener(new ButtonClickListener());
controlPanel.add(okButton);
controlPanel.add(submitButton);
//controlPanel.add(cancelButton);
controlPanel.add(textField);
System.out.println("---------------------");
mainFrame.setVisible(true);
}
private class ButtonClickListener implements ActionListener{
public void actionPerformed(ActionEvent e) {
String command = e.getActionCommand();
if( command.equals( "reload" )) {
statusLabel.setText(convertToMultiline("Line1\nLine2\nLine3\nLine4\nLine5\nLine6\nLine7\nLine8\nLine9\nLine2\nLine3\nLine\nLine2\nLine3\nLine\nLine2\nLine3\nLine\nLine2\nLine3\nLine\nLine2\nLine3\nLine\nLine2\nLine3\nLine\nLine2\nLine3\nLine"));
}
else {
statusLabel.setText("Submit Button clicked.");
}
}
}
public static String convertToMultiline(String orig)
{
return "<html>" + orig.replaceAll("\n", "<br>");
}
}
The GUI need to look like this
I want to remove the large vertical gaps between the componets, and the jLabel should use that space
Well in your comment you say you want the label to use the space. But in your picture you show the text area with all the space. How can we answer a question when you give us conflicting requirements? Be specific and accurate when describing a problem.
In any case, the default layout of a JFrame is a BorderLayout so you would probably start with that.
Then the component that you want to grow/shrink as the frame is resized should be added to the CENTER of the frame.
Then you create a second panel to contain your other components. This panel would then be added to either the PAGE_START or PAGE_NORTH of the frame depending on your exact requirement.
The layout manager of this panel can then be whatever your want. Maybe a GridLayout, or a GridBagLayout or a vertical BoxLayout.
Read the section from the Swing tutorial on Layout Managers for more information and working examples. The key point is you create nest panels each with a different layout manager to achieve your layout.
I have been trying to learn Buttons but it refuses to resize. Button1 (code below) just takes up the whole screen. I have seen other posts who's problem was that they didn't use
setMaximumSize();
but I'm using it and it still isn't working! I didn't make a JPanel yet. Here is my JFrame:
import java.awt.Dimension;
import javax.swing.JButton;
import javax.swing.JFrame;
public class Frame extends JFrame {
private JButton button1;
private JButton button2;
public Frame()
{
button1 = new JButton("Hello button1");
button2 = new JButton("Hello button2");
button2.setMaximumSize(new Dimension(100,100));
button1.setMaximumSize(new Dimension(100,100));
add(button2);
add(button1);
}
}
My main class is plain and simple:
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Panel extends JPanel{
public static void main(String args [])
{
Frame frame = new Frame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(500, 500);
frame.setVisible(true);
}
}
It's because the frame('s contentPane) has a BorderLayout by default. You add the buttons to BorderLayout.CENTER, so the layout manager ignores the minimum-, preferred- and maximumSize.
I just want them to come up small and side by side
For that you could use a simple FlowLayout. (And if you want them to be centered on the frame, a parent JPanel with a GridBagLayout)
If you want a custom width & height for the buttons, override their getPreferredSize method. Overriding this method is safer than calling setPreferredSize.
Example:
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.GridBagLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Example {
public Example() {
JButton button1 = new JButton("Hello button1");
JButton button2 = new JButton("Hello button2") {
#Override
public Dimension getPreferredSize() {
int width = super.getPreferredSize().width;
return new Dimension(width, width);
}
};;
JPanel buttonPanel = new JPanel();
buttonPanel.add(button1);
buttonPanel.add(button2);
JPanel contentPanel = new JPanel(new GridBagLayout());
contentPanel.add(buttonPanel);
JFrame frame = new JFrame();
frame.setContentPane(contentPanel);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(400, 400);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
new Example();
}
});
}
}
I added a flowlayout and changed setMaximumSize to setPreferredSize. That should fix your problem.
Here try this:
import java.awt.Dimension;
import javax.swing.JButton;
import javax.swing.JFrame;
public class Frame extends JFrame {
private JButton button1;
private JButton button2;
public Frame()
{
button1 = new JButton("Hello button1");
button2 = new JButton("Hello button2");
button2.setPreferredSize(new Dimension(100,100));
button1.setPreferredSize(new Dimension(100,100));
add(button2);
add(button1);
}
}
<----now the other class--->
import java.awt.FlowLayout;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Panel extends JPanel{
public static void main(String args [])
{
Frame frame = new Frame();
frame.setLayout(new FlowLayout());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(500, 500);
frame.setVisible(true);
}
}
I am trying to create a Java GUI application that contains a label and button. When the button is clicked the background color of the first panel is changed. I've got the label and button but getting errors whenever I click the button. Also, I wanted the first panel to originally have a yellow background then switch to whatever color. Here's my code:
import javax.swing.JFrame;
import javax.swing.JPanel;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.GridLayout;
import java.awt.FlowLayout;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.JLabel;
public class ChangeDemo extends JFrame implements ActionListener
{
public static final int WIDTH = 300;
public static final int HEIGHT= 200;
private JPanel biggerPanel;
public static void main(String[] args)
{
ChangeDemo gui = new ChangeDemo();
gui.setVisible(true);
}
public ChangeDemo()
{
super ("ChangeBackgroundDemo");
setSize(WIDTH,HEIGHT);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLayout(new GridLayout(2,3));
JPanel biggerPanel = new JPanel();
biggerPanel.setLayout(new BorderLayout());
biggerPanel.setBackground(Color.YELLOW);
JLabel namePanel = new JLabel("Click the button to change the background color");
biggerPanel.add(namePanel, BorderLayout.NORTH);
add(namePanel);
JPanel buttonPanel = new JPanel();
buttonPanel.setLayout(new FlowLayout());
buttonPanel.setBackground(Color.LIGHT_GRAY);
JButton changeButton = new JButton("Change Color");
changeButton.addActionListener(this);
buttonPanel.add(changeButton);
add(buttonPanel);
}
public void actionPerformed(ActionEvent e)
{
String buttonString = e.getActionCommand();
if(buttonString.equals("Change Color"))
biggerPanel.setBackground(Color.RED);
else
System.out.println("Unexpected Error!");
}
}
I made a few changes to your code.
First, you must start a Swing application with a call to SwingUtilities.invokeLater.
public static void main(String[] args) {
SwingUtilities.invokeLater(new ChangeDemo());
}
Second, you use Swing components. You only extend a Swing component when you want to override a method of the Swing component.
Third, I made a action listener specifically for your JButton. That way, you don't have to check for a particular JButton string. You can create as many action listeners as you need for your GUI.
JButton changeButton = new JButton("Change Color");
changeButton.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent event) {
isYellow = !isYellow;
if (isYellow) buttonPanel.setBackground(Color.YELLOW);
else buttonPanel.setBackground(Color.RED);
}
});
Finally, I changed the background color of the JButton panel.
Here's the entire ChangeDemo class.
package com.ggl.testing;
import java.awt.Color;
import java.awt.FlowLayout;
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.SwingUtilities;
public class ChangeDemo implements Runnable {
private boolean isYellow;
private JFrame frame;
public static void main(String[] args) {
SwingUtilities.invokeLater(new ChangeDemo());
}
#Override
public void run() {
frame = new JFrame("Change Background Demo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel mainPanel = new JPanel();
mainPanel.setLayout(new BoxLayout(mainPanel, BoxLayout.PAGE_AXIS));
JPanel namePanel = new JPanel();
JLabel nameLabel = new JLabel(
"Click the button to change the background color");
nameLabel.setAlignmentX(JLabel.CENTER_ALIGNMENT);
namePanel.add(nameLabel);
mainPanel.add(namePanel);
final JPanel buttonPanel = new JPanel();
buttonPanel.setLayout(new FlowLayout());
buttonPanel.setBackground(Color.YELLOW);
isYellow = true;
JButton changeButton = new JButton("Change Color");
changeButton.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent event) {
isYellow = !isYellow;
if (isYellow) buttonPanel.setBackground(Color.YELLOW);
else buttonPanel.setBackground(Color.RED);
}
});
buttonPanel.add(changeButton);
mainPanel.add(buttonPanel);
frame.add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
}
Here is working demo based on amendments to your code, haven't had time to tidy it up but hopefully you'll get the gist of it. Problem was you hand't added Panels to the borders (north, south etc.) in order to color them. Hopefully this helps.
import javax.swing.JFrame;
import javax.swing.JPanel;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.GridLayout;
import java.awt.FlowLayout;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.JLabel;
public class ChangeDemo extends JFrame implements ActionListener
{
public static final int WIDTH = 300;
public static final int HEIGHT= 200;
private JPanel biggerPanel = new JPanel();
private JPanel namePanel = new JPanel();
public static void main(String[] args)
{
ChangeDemo gui = new ChangeDemo();
gui.setVisible(true);
}
public ChangeDemo()
{
super ("ChangeBackgroundDemo");
setSize(WIDTH,HEIGHT);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLayout(new GridLayout(2,3));
//JPanel biggerPanel = new JPanel();
this.biggerPanel.setLayout(new BorderLayout());
this.biggerPanel.setBackground(Color.YELLOW);
JLabel nameLabel = new JLabel("Click the button to change the background color");
namePanel.add(nameLabel);
namePanel.setBackground(Color.YELLOW);
//this.biggerPanel.add(namePanel, BorderLayout.NORTH);
add(namePanel);
JPanel buttonPanel = new JPanel();
buttonPanel.setLayout(new FlowLayout());
buttonPanel.setBackground(Color.LIGHT_GRAY);
JButton changeButton = new JButton("Change Color");
changeButton.addActionListener(this);
changeButton.setActionCommand("Change Color");
buttonPanel.add(changeButton);
add(buttonPanel);
}
public void actionPerformed(ActionEvent e)
{
String buttonString = e.getActionCommand();
if(buttonString.equals("Change Color"))
this.namePanel.setBackground(Color.RED);
else
System.out.println("Unexpected Error!");
}
}
I'm currently writing an interface where a have a JFrame class and two JPanel classes. When the script is first executed, Panel A is shown. I have a JButton in Panel A which I would like, when clicked, to display Panel B instead of Panel A.
Is there any way I could do this?
Read tutorial for that.
You can use next() method of CardLayout for showing next card,
or you can use show(...); for showing specific card.
Simple example:
import java.awt.BorderLayout;
import java.awt.CardLayout;
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;
public class Example {
public static void main(String[] args){
JFrame frame = new JFrame();
final JPanel panel = new JPanel(new CardLayout());
JLabel l1 = new JLabel("1");
JLabel l2 = new JLabel("2");
JLabel l3 = new JLabel("3");
panel.add(l1,"l1");
panel.add(l2,"l2");
panel.add(l3,"l3");
JButton btn = new JButton("next");
btn.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent arg0) {
CardLayout layout = (CardLayout) panel.getLayout();
layout.next(panel);
}
});
JButton btnSpec = new JButton("l3");
btnSpec.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent arg0) {
CardLayout layout = (CardLayout) panel.getLayout();
layout.show(panel, "l3");
}
});
frame.add(panel);
frame.add(btn,BorderLayout.SOUTH);
frame.add(btnSpec,BorderLayout.NORTH);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
}