Develop Reference

About java swing Linked label [duplicate]

I want to learn how to write an ActionListener for JLabel. I want to make a label that open a new frame for user when user clicks the label. Maybe MouseListener can work but I do not know how to make it.

I recommend using a JTextField rather than a JLabel for this use.
Being based on a component designed to be focusable, it allows an ActionListener and looks and feels more like an HTML link.
E.G.
That is how it appears when the mouse is hovering over the first link.
LinkLabel
/* License - LGPL
LinkLabel Using the Desktop Class
There are a lot of link labels. This one uses the Java 1.6+
Desktop class for its functionality, and is thereby suitable
for applets, applications launched using JWS, and 'standard'
(non-JWS) desktop applications.
Note that the Desktop class can be used with pre 1.6 JREs. It
is available through JDIC.
https://jdic.dev.java.net/nonav/documentation/javadoc/jdic/org/jdesktop/jdic/desktop/Desktop.html
*/
import java.awt.Desktop;
import java.awt.Color;
import java.awt.Cursor;
import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.event.*;
import javax.swing.JTextField;
import javax.swing.JPanel;
import javax.swing.JOptionPane;
import javax.swing.border.MatteBorder;
import javax.swing.border.Border;
import java.net.URI;
import java.io.File;
/**
A Java 1.6+ LinkLabel that uses the Desktop class for opening
the document of interest.
The Desktop.browse(URI) method can be invoked from applications,
applets and apps. launched using Java Webstart. In the latter
two cases, the usual fall-back methods are used for sandboxed apps
(see the JavaDocs for further details).
While called a 'label', this class actually extends JTextField,
to easily allow the component to become focusable using keyboard
navigation.
To successfully browse to a URI for a local File, the file name
must be constructed using a canonical path.
#author Andrew Thompson
#version 2008/08/23
*/
public class LinkLabel
// we extend a JTextField, to get a focusable component
extends JTextField
implements MouseListener, FocusListener, ActionListener {
/** The target or href of this link. */
private URI target;
public Color standardColor = new Color(0,0,255);
public Color hoverColor = new Color(255,0,0);
public Color activeColor = new Color(128,0,128);
public Color transparent = new Color(0,0,0,0);
public boolean underlineVisible = true;
private Border activeBorder;
private Border hoverBorder;
private Border standardBorder;
/** Construct a LinkLabel that points to the given target.
The URI will be used as the link text.*/
public LinkLabel(URI target) {
this( target, target.toString() );
}
/** Construct a LinkLabel that points to the given target,
and displays the text to the user. */
public LinkLabel(URI target, String text) {
super(text);
this.target = target;
}
/* Set the active color for this link (default is purple). */
public void setActiveColor(Color active) {
activeColor = active;
}
/* Set the hover/focused color for this link (default is red). */
public void setHoverColor(Color hover) {
hoverColor = hover;
}
/* Set the standard (non-focused, non-active) color for this
link (default is blue). */
public void setStandardColor(Color standard) {
standardColor = standard;
}
/** Determines whether the */
public void setUnderlineVisible(boolean underlineVisible) {
this.underlineVisible = underlineVisible;
}
/* Add the listeners, configure the field to look and act
like a link. */
public void init() {
this.addMouseListener(this);
this.addFocusListener(this);
this.addActionListener(this);
setToolTipText(target.toString());
if (underlineVisible) {
activeBorder = new MatteBorder(0,0,1,0,activeColor);
hoverBorder = new MatteBorder(0,0,1,0,hoverColor);
standardBorder = new MatteBorder(0,0,1,0,transparent);
} else {
activeBorder = new MatteBorder(0,0,0,0,activeColor);
hoverBorder = new MatteBorder(0,0,0,0,hoverColor);
standardBorder = new MatteBorder(0,0,0,0,transparent);
}
// make it appear like a label/link
setEditable(false);
setForeground(standardColor);
setBorder(standardBorder);
setCursor( new Cursor(Cursor.HAND_CURSOR) );
}
/** Browse to the target URI using the Desktop.browse(URI)
method. For visual indication, change to the active color
at method start, and return to the standard color once complete.
This is usually so fast that the active color does not appear,
but it will take longer if there is a problem finding/loading
the browser or URI (e.g. for a File). */
public void browse() {
setForeground(activeColor);
setBorder(activeBorder);
try {
Desktop.getDesktop().browse(target);
} catch(Exception e) {
e.printStackTrace();
}
setForeground(standardColor);
setBorder(standardBorder);
}
/** Browse to the target. */
public void actionPerformed(ActionEvent ae) {
browse();
}
/** Browse to the target. */
public void mouseClicked(MouseEvent me) {
browse();
}
/** Set the color to the hover color. */
public void mouseEntered(MouseEvent me) {
setForeground(hoverColor);
setBorder(hoverBorder);
}
/** Set the color to the standard color. */
public void mouseExited(MouseEvent me) {
setForeground(standardColor);
setBorder(standardBorder);
}
public void mouseReleased(MouseEvent me) {}
public void mousePressed(MouseEvent me) {}
/** Set the color to the standard color. */
public void focusLost(FocusEvent fe) {
setForeground(standardColor);
setBorder(standardBorder);
}
/** Set the color to the hover color. */
public void focusGained(FocusEvent fe) {
setForeground(hoverColor);
setBorder(hoverBorder);
}
public static void main(String[] args) throws Exception {
JPanel p = new JPanel(new GridLayout(0,1));
File f = new File(".","LinkLabel.java");
/* Filename must be constructed with a canonical path in
order to successfully use Desktop.browse(URI)! */
f = new File(f.getCanonicalPath());
URI uriFile = f.toURI();
LinkLabel linkLabelFile = new LinkLabel(uriFile);
linkLabelFile.init();
p.add(linkLabelFile);
LinkLabel linkLabelWeb = new LinkLabel(
new URI("http://sscce.org/"),
"SSCCE");
linkLabelWeb.setStandardColor(new Color(0,128,0));
linkLabelWeb.setHoverColor(new Color(222,128,0));
linkLabelWeb.init();
/* This shows a quirk of the LinkLabel class, the
size of the text field needs to be constrained to
get the underline to appear properly. */
p.add(linkLabelWeb);
LinkLabel linkLabelConstrain = new LinkLabel(
new URI("http://sdnshare.sun.com/"),
"SDN Share");
linkLabelConstrain.init();
/* ..and this shows one way to constrain the size
(appropriate for this layout).
Similar tricks can be used to ensure the underline does
not drop too far *below* the link (think BorderLayout
NORTH/SOUTH).
The same technique can also be nested further to produce
a NORTH+EAST packing (for example). */
JPanel labelConstrain = new JPanel(new BorderLayout());
labelConstrain.add( linkLabelConstrain, BorderLayout.EAST );
p.add(labelConstrain);
LinkLabel linkLabelNoUnderline = new LinkLabel(
new URI("http://java.net/"),
"java.net");
// another way to deal with the underline is to remove it
linkLabelNoUnderline.setUnderlineVisible(false);
// we can use the methods inherited from JTextField
linkLabelNoUnderline.
setHorizontalAlignment(JTextField.CENTER);
linkLabelNoUnderline.init();
p.add(linkLabelNoUnderline);
JOptionPane.showMessageDialog( null, p );
}
}

JDialogPane with Focused password input field [duplicate]

When my application loads, which is made using netbeans, the first JTextField is automatically focused, and in this JTextField, I have written "Enter your Username", it will go away when the user clicks on this field, but when the application is loaded, this field is focused, means I can't see "Enter your Username", how to unfocus it on startup ?

A log-in would be best done in a modal dialog, but that introduces problems in that the method requestFocusInWindow() must be called after the component is visible, but that is blocked by the fact the dialog is modal!
This example uses Rob Camick's RequestFocusListener (as presented in Dialog Focus) to manage focus after the dialog is visible.
Note: That is how it appears before the user does anything. The password field is focused by default.
import java.awt.*;
import javax.swing.*;
import javax.swing.event.*;
public class LoginRequired {
LoginRequired() {
JFrame f = new JFrame("Login Required");
f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
f.setResizable(false);
f.setSize(400, 300); // not recommended, but used here for convenience
f.setLocationByPlatform(true);
f.setVisible(true);
showLogin(f);
}
private void showLogin(JFrame frame) {
JPanel p = new JPanel(new BorderLayout(5,5));
JPanel labels = new JPanel(new GridLayout(0,1,2,2));
labels.add(new JLabel("User Name", SwingConstants.TRAILING));
labels.add(new JLabel("Password", SwingConstants.TRAILING));
p.add(labels, BorderLayout.LINE_START);
JPanel controls = new JPanel(new GridLayout(0,1,2,2));
JTextField username = new JTextField("Joe Blogs");
controls.add(username);
JPasswordField password = new JPasswordField();
password.addAncestorListener(new RequestFocusListener(false));
controls.add(password);
p.add(controls, BorderLayout.CENTER);
JOptionPane.showMessageDialog(
frame, p, "Log In", JOptionPane.QUESTION_MESSAGE);
System.out.println("User Name: " + username.getText());
System.out.println("Password: " + new String(password.getPassword()));
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> {
new LoginRequired();
});
}
}
/**
* Convenience class to request focus on a component.
*
* When the component is added to a realized Window then component will
* request focus immediately, since the ancestorAdded event is fired
* immediately.
*
* When the component is added to a non realized Window, then the focus
* request will be made once the window is realized, since the
* ancestorAdded event will not be fired until then.
*
* Using the default constructor will cause the listener to be removed
* from the component once the AncestorEvent is generated. A second constructor
* allows you to specify a boolean value of false to prevent the
* AncestorListener from being removed when the event is generated. This will
* allow you to reuse the listener each time the event is generated.
*/
class RequestFocusListener implements AncestorListener
{
private boolean removeListener;
/*
* Convenience constructor. The listener is only used once and then it is
* removed from the component.
*/
public RequestFocusListener()
{
this(true);
}
/*
* Constructor that controls whether this listen can be used once or
* multiple times.
*
* #param removeListener when true this listener is only invoked once
* otherwise it can be invoked multiple times.
*/
public RequestFocusListener(boolean removeListener)
{
this.removeListener = removeListener;
}
#Override
public void ancestorAdded(AncestorEvent e)
{
JComponent component = e.getComponent();
component.requestFocusInWindow();
if (removeListener)
component.removeAncestorListener( this );
}
#Override
public void ancestorMoved(AncestorEvent e) {}
#Override
public void ancestorRemoved(AncestorEvent e) {}
}

textField.setFocusable(false);
textField.setFocusable(true);
If, and only if, textField had focus, the next component in TAB-order order will get focus automatically. The effect is the same as a TAB press.
(not tested in a GUI with just one focusable component :) )

Use requestFocusInWindow() to set focus on some other component rather then your JTextfield first.
But i'd suggest not to alter the native focus system, rather setText(String s) on the JTextField after initComponents() call in the constructor (assumed to be in netbeans).
Further optional reading: How to Use the Focus Subsystem

I think giving keyboard focus to the username field is the correct behavior, assuming that's what the user needs to do first. Instead of clearing on focus, why not clear only after the user types something?:
import java.awt.*;
import javax.swing.*;
import javax.swing.text.Document;
public class PlaceholderTextField extends JTextField {
public static void main(final String[] args) {
final PlaceholderTextField tf = new PlaceholderTextField("");
tf.setColumns(20);
tf.setPlaceholder("All your base are belong to us!");
final Font f = tf.getFont();
tf.setFont(new Font(f.getName(), f.getStyle(), 30));
JOptionPane.showMessageDialog(null, tf);
}
private String placeholder;
public PlaceholderTextField() {
}
public PlaceholderTextField(
final Document pDoc,
final String pText,
final int pColumns)
{
super(pDoc, pText, pColumns);
}
public PlaceholderTextField(final int pColumns) {
super(pColumns);
}
public PlaceholderTextField(final String pText) {
super(pText);
}
public PlaceholderTextField(final String pText, final int pColumns) {
super(pText, pColumns);
}
public String getPlaceholder() {
return placeholder;
}
#Override
protected void paintComponent(final Graphics pG) {
super.paintComponent(pG);
if (placeholder.length() == 0 || getText().length() > 0) {
return;
}
final Graphics2D g = (Graphics2D) pG;
g.setRenderingHint(
RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
g.setColor(getDisabledTextColor());
g.drawString(placeholder, getInsets().left, pG.getFontMetrics()
.getMaxAscent() + getInsets().top);
}
public void setPlaceholder(final String s) {
placeholder = s;
}
}
If you really just want to remove focus, some options:
component.setFocusable(false);
KeyboardFocusManager.getCurrentKeyboardFocusManager().focusNextComponent();
KeyboardFocusManager.getCurrentKeyboardFocusManager().clearGlobalFocusOwner();

ActionListener for JLabel

I want to learn how to write an ActionListener for JLabel. I want to make a label that open a new frame for user when user clicks the label. Maybe MouseListener can work but I do not know how to make it.

I recommend using a JTextField rather than a JLabel for this use.
Being based on a component designed to be focusable, it allows an ActionListener and looks and feels more like an HTML link.
E.G.
That is how it appears when the mouse is hovering over the first link.
LinkLabel
/* License - LGPL
LinkLabel Using the Desktop Class
There are a lot of link labels. This one uses the Java 1.6+
Desktop class for its functionality, and is thereby suitable
for applets, applications launched using JWS, and 'standard'
(non-JWS) desktop applications.
Note that the Desktop class can be used with pre 1.6 JREs. It
is available through JDIC.
https://jdic.dev.java.net/nonav/documentation/javadoc/jdic/org/jdesktop/jdic/desktop/Desktop.html
*/
import java.awt.Desktop;
import java.awt.Color;
import java.awt.Cursor;
import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.event.*;
import javax.swing.JTextField;
import javax.swing.JPanel;
import javax.swing.JOptionPane;
import javax.swing.border.MatteBorder;
import javax.swing.border.Border;
import java.net.URI;
import java.io.File;
/**
A Java 1.6+ LinkLabel that uses the Desktop class for opening
the document of interest.
The Desktop.browse(URI) method can be invoked from applications,
applets and apps. launched using Java Webstart. In the latter
two cases, the usual fall-back methods are used for sandboxed apps
(see the JavaDocs for further details).
While called a 'label', this class actually extends JTextField,
to easily allow the component to become focusable using keyboard
navigation.
To successfully browse to a URI for a local File, the file name
must be constructed using a canonical path.
#author Andrew Thompson
#version 2008/08/23
*/
public class LinkLabel
// we extend a JTextField, to get a focusable component
extends JTextField
implements MouseListener, FocusListener, ActionListener {
/** The target or href of this link. */
private URI target;
public Color standardColor = new Color(0,0,255);
public Color hoverColor = new Color(255,0,0);
public Color activeColor = new Color(128,0,128);
public Color transparent = new Color(0,0,0,0);
public boolean underlineVisible = true;
private Border activeBorder;
private Border hoverBorder;
private Border standardBorder;
/** Construct a LinkLabel that points to the given target.
The URI will be used as the link text.*/
public LinkLabel(URI target) {
this( target, target.toString() );
}
/** Construct a LinkLabel that points to the given target,
and displays the text to the user. */
public LinkLabel(URI target, String text) {
super(text);
this.target = target;
}
/* Set the active color for this link (default is purple). */
public void setActiveColor(Color active) {
activeColor = active;
}
/* Set the hover/focused color for this link (default is red). */
public void setHoverColor(Color hover) {
hoverColor = hover;
}
/* Set the standard (non-focused, non-active) color for this
link (default is blue). */
public void setStandardColor(Color standard) {
standardColor = standard;
}
/** Determines whether the */
public void setUnderlineVisible(boolean underlineVisible) {
this.underlineVisible = underlineVisible;
}
/* Add the listeners, configure the field to look and act
like a link. */
public void init() {
this.addMouseListener(this);
this.addFocusListener(this);
this.addActionListener(this);
setToolTipText(target.toString());
if (underlineVisible) {
activeBorder = new MatteBorder(0,0,1,0,activeColor);
hoverBorder = new MatteBorder(0,0,1,0,hoverColor);
standardBorder = new MatteBorder(0,0,1,0,transparent);
} else {
activeBorder = new MatteBorder(0,0,0,0,activeColor);
hoverBorder = new MatteBorder(0,0,0,0,hoverColor);
standardBorder = new MatteBorder(0,0,0,0,transparent);
}
// make it appear like a label/link
setEditable(false);
setForeground(standardColor);
setBorder(standardBorder);
setCursor( new Cursor(Cursor.HAND_CURSOR) );
}
/** Browse to the target URI using the Desktop.browse(URI)
method. For visual indication, change to the active color
at method start, and return to the standard color once complete.
This is usually so fast that the active color does not appear,
but it will take longer if there is a problem finding/loading
the browser or URI (e.g. for a File). */
public void browse() {
setForeground(activeColor);
setBorder(activeBorder);
try {
Desktop.getDesktop().browse(target);
} catch(Exception e) {
e.printStackTrace();
}
setForeground(standardColor);
setBorder(standardBorder);
}
/** Browse to the target. */
public void actionPerformed(ActionEvent ae) {
browse();
}
/** Browse to the target. */
public void mouseClicked(MouseEvent me) {
browse();
}
/** Set the color to the hover color. */
public void mouseEntered(MouseEvent me) {
setForeground(hoverColor);
setBorder(hoverBorder);
}
/** Set the color to the standard color. */
public void mouseExited(MouseEvent me) {
setForeground(standardColor);
setBorder(standardBorder);
}
public void mouseReleased(MouseEvent me) {}
public void mousePressed(MouseEvent me) {}
/** Set the color to the standard color. */
public void focusLost(FocusEvent fe) {
setForeground(standardColor);
setBorder(standardBorder);
}
/** Set the color to the hover color. */
public void focusGained(FocusEvent fe) {
setForeground(hoverColor);
setBorder(hoverBorder);
}
public static void main(String[] args) throws Exception {
JPanel p = new JPanel(new GridLayout(0,1));
File f = new File(".","LinkLabel.java");
/* Filename must be constructed with a canonical path in
order to successfully use Desktop.browse(URI)! */
f = new File(f.getCanonicalPath());
URI uriFile = f.toURI();
LinkLabel linkLabelFile = new LinkLabel(uriFile);
linkLabelFile.init();
p.add(linkLabelFile);
LinkLabel linkLabelWeb = new LinkLabel(
new URI("http://sscce.org/"),
"SSCCE");
linkLabelWeb.setStandardColor(new Color(0,128,0));
linkLabelWeb.setHoverColor(new Color(222,128,0));
linkLabelWeb.init();
/* This shows a quirk of the LinkLabel class, the
size of the text field needs to be constrained to
get the underline to appear properly. */
p.add(linkLabelWeb);
LinkLabel linkLabelConstrain = new LinkLabel(
new URI("http://sdnshare.sun.com/"),
"SDN Share");
linkLabelConstrain.init();
/* ..and this shows one way to constrain the size
(appropriate for this layout).
Similar tricks can be used to ensure the underline does
not drop too far *below* the link (think BorderLayout
NORTH/SOUTH).
The same technique can also be nested further to produce
a NORTH+EAST packing (for example). */
JPanel labelConstrain = new JPanel(new BorderLayout());
labelConstrain.add( linkLabelConstrain, BorderLayout.EAST );
p.add(labelConstrain);
LinkLabel linkLabelNoUnderline = new LinkLabel(
new URI("http://java.net/"),
"java.net");
// another way to deal with the underline is to remove it
linkLabelNoUnderline.setUnderlineVisible(false);
// we can use the methods inherited from JTextField
linkLabelNoUnderline.
setHorizontalAlignment(JTextField.CENTER);
linkLabelNoUnderline.init();
p.add(linkLabelNoUnderline);
JOptionPane.showMessageDialog( null, p );
}
}

JComboBox not showing arrow

I have been searching this site and google for a solution to my problem, and I can't find anything. I think it's supposed to just work; however, it doesn't. The arrow icon for my JComboBox doesn't show up, and I can't find anywhere to set its visibility to true.
Here's my code:
public class Driver implements ActionListener {
private JTextField userIDField;
private JTextField[] documentIDField;
private JComboBox repository, environment;
private JButton close, clear, submit;
private JFrame window;
public Driver()
{
window = makeWindow();
makeContents(window);
window.repaint();
}
private JFrame makeWindow()
{
JFrame window = new JFrame("");
window.setSize(500,300);
window.setLocation(50,50);
window.getContentPane().setLayout(null);
window.setResizable(false);
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
window.setVisible(true);
return window;
}
private void makeContents(JFrame w)
{
makeDropDowns(w);
w.repaint();
}
private void makeDropDowns(JFrame w)
{
String[] repositoryArray = {"Click to select", "NSA", "Finance", "Test"};
repository = new JComboBox(repositoryArray);
repository.setSelectedIndex(0);
repository.addActionListener(this);
repository.setSize(150,20);
repository.setLocation(175,165);
repository.setEditable(false);
w.add(repository);
String[] environmentArray = {"Click to select", "Dev", "Test", "Qual"};
environment = new JComboBox(environmentArray);
environment.setSelectedIndex(0);
environment.addActionListener(this);
environment.setSize(150,20);
environment.setLocation(175,195);
//environment.setEditable(false);
w.add(environment,0);
}
public void actionPerformed(ActionEvent e)
{
String repositoryID = "null", environmentID = "null";
if (e.getSource() == repository)
{
repositoryID = (String)repository.getSelectedItem();
}
if(e.getSource() == environment)
{
environmentID = (String)environment.getSelectedItem();
}
}
}
Here's a link to a picture of the problem:
If anyone could help that would be awesome.

It doesn't appear to be the issue you were suffering from, but I found this post due to the same resulting issue of the arrow disappearing.
In my case it was due to me mistakenly using .removeAll() on the JComboBox rather than .removeAllItems() when I was attempting to empty and then reuse the JComboBox after a refresh of the data I was using. Just thought I'd include it as an answer in case someone else comes across this thread for similar reasons.

The code you show works, but it looks like you're fighting the enclosing container's default layout. Here, ComboTest is a JPanel which defaults to FlowLayout.
Addendum: In general, do not use absolute positioning, as shown in your update. I've changed the example to use GridLayout; comment out the setLayout() call to see the default, FlowLayout.
import java.awt.EventQueue;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JPanel;
/**
* #see https://stackoverflow.com/a/10824504/230513
*/
public class ComboTest extends JPanel {
private JComboBox repository = createCombo(new String[]{
"Click to select", "NSA", "Finance", "Test"});
private JComboBox environment = createCombo(new String[]{
"Click to select", "Dev", "Test", "Qual"});
public ComboTest() {
this.setLayout(new GridLayout(0, 1));
this.add(repository);
this.add(environment);
}
private JComboBox createCombo(String[] data) {
final JComboBox combo = new JComboBox(data);
combo.setSelectedIndex(1);
combo.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
System.out.println(e.getActionCommand()
+ ": " + combo.getSelectedItem().toString());
}
});
return combo;
}
private void display() {
JFrame f = new JFrame("ComboTest");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.add(this);
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
new ComboTest().display();
}
});
}
}

I had the same issue. I fixed it by revalidating and repainting the panel with the following code :
myPanel.revalidate();
myPanel.repaint();

Maybe a little late, but for those who are still looking for an easy and fail-safe way to use the JComboBox can use this:
public class FixedJComboBox<E>
extends JComboBox<E> {
// Copied constructors
public FixedJComboBox() {
super();
}
public FixedJComboBox(ComboBoxModel<E> aModel) {
super(aModel);
}
public FixedJComboBox(E[] items) {
super(items);
}
public FixedJComboBox(Vector<E> items) {
super(items);
}
#Override
public void setBounds(int x, int y, int width, int height) {
super.setBounds(x, y, width, height);
// The arrow is the first (and only) component
// that is added by default
Component[] comps = getComponents();
if (comps != null && comps.length >= 1) {
Component arrow = comps[0];
// 20 is the default width of the arrow (for me at least)
arrow.setSize(20, height);
arrow.setLocation(width - arrow.getWidth(), 0);
}
}
}
As described here, the bug is caused by incorrectly setting both the location and the size of the arrow to (0,0), followed by some repainting issues. By simply overriding the setBounds() function, the arrow is always corrected after the UI/layout manager has wrongly updated the arrow.
Also, since new components are added after the old ones (i.e. higher index), the arrow will always be at the first element in the array (assuming you don't remove and re-add the arrow).
The disadvantage is of this class is that the width of the arrow is now determined by a constant instead of the UI/layout manager.

How can I get the Caps Lock state, and set it to on, if it isn't already?

I would like a specific example on how to turn caps lock on if it is off.
I know how to toggle the key, I have been using this:
toolkit.setLockingKeyState(KeyEvent.VK_CAPS_LOCK, Boolean.TRUE);
That will change the state of the key whether it is on or off.
But I want to make sure it is on at the beginning of the application.
(The final goal is having the keyboard LEDs flash in certain sequences, which works better if I have a certain starting state.)

You can use getLockingKeyState to check if Caps Lock is currently set:
boolean isOn = Toolkit.getDefaultToolkit().getLockingKeyState(KeyEvent.VK_CAPS_LOCK);
However, it's unnecessary -- setLockingKeyState doesn't toggle the state of the key, it sets it. If you pass it true it will set the key state to on regardless of the original state:
Toolkit.getDefaultToolkit().setLockingKeyState(KeyEvent.VK_CAPS_LOCK, true);

/*
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* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/
package javaapplication52;
import java.awt.Toolkit;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import javax.swing.JFrame;
import javax.swing.JTextField;
/**
*
* #author DSF Inc - Admin
*/
public class JavaApplication52 extends JFrame {
JavaApplication52() {
setLayout(null);
JTextField t = new JTextField();
t.setBounds(0,0,300,20);
add(t);
t.addKeyListener(new KeyAdapter() {
#Override
public void keyPressed(KeyEvent e) {
boolean isOn = Toolkit.getDefaultToolkit().getLockingKeyState(KeyEvent.VK_CAPS_LOCK);
if (isOn == true) {
System.err.println("ON");
} else {
System.err.println("OFF");
}
}
});
setSize(300, 400);
setVisible(true);
setResizable(false);
setLocationRelativeTo(null);
setDefaultCloseOperation(DO_NOTHING_ON_CLOSE);
}
/**
* #param args the command line arguments
*/
public static void main(String[] args) {
JavaApplication52 fr = new JavaApplication52();
}
}

Toolkit toolkit = Toolkit.getDefaultToolkit();
robik.keyPress(KeyEvent.VK_SPACE); // PRESS ANY KEY // Any key needs to be pressed
Toolkit.getDefaultToolkit().setLockingKeyState(KeyEvent.VK_CAPS_LOCK, true);
robik.keyRelease(KeyEvent.VK_SPACE);