Develop Reference

Dynamic resizing of JMenu after adding items at runtime

As in title, I struggle to get my JMenu to resize when programatically adding components. In my application I need JMenu with JCheckBoxes. Whenever I tick one of them, JSlider should appear just below. Below is the code that makes that happen. The problem I have is that when there's lot of sliders visible, items in JMenu get clumped - see image below.
How can I force redraw/resize/expansion of JMenu to perserve original checkboxes/sliders height?
Also note - JMenu stays visible at all times when selecting checkboxes. It closes only when I click outside of it. But after such 'restart' menu grows and problem is no longer present.
Many thanks in advance!
public class Window extends JFrame implements ActionListener {
private JPanel panel;
private JMenuBar menuBar;
private JMenu menu;
private JSlider slider1;
private JCheckBoxMenuItem checkBox1;
private JCheckBoxMenuItem checkBox2;
private JCheckBoxMenuItem checkBox3;
public Window() {
super("Example");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setMinimumSize(new Dimension(300,300));
panel = new JPanel();
panel.setMinimumSize(new Dimension(300,300));
menuBar = new JMenuBar();
menu = new JMenu("Options");
checkBox1 = new JCheckBoxMenuItem("option 1");
checkBox2 = new JCheckBoxMenuItem("option 2");
checkBox3 = new JCheckBoxMenuItem("option 3");
checkBox1.addActionListener(this);
//prevent JMenu from closing after selecting CheckBox
checkBox1.setUI(new BasicCheckBoxMenuItemUI() {
#Override
protected void doClick(MenuSelectionManager msm) {
checkBox1.doClick(0);
}
});
slider1 = new JSlider();
slider1.setVisible(false);
menu.add(checkBox1);
menu.add(slider1);
menu.add(checkBox2);
menu.add(checkBox3);
menuBar.add(menu);
setJMenuBar(menuBar);
add(panel);
setVisible(true);
}
#Override
public void actionPerformed(ActionEvent e) {
if (e.getSource().equals(checkBox1)) {
slider1.setVisible(checkBox1.isSelected());
}
}
}
Here's screen from my main application:

Hiding and reshowing the popup menu will cause it to be resized:
#Override
public void actionPerformed(ActionEvent e) {
if (e.getSource().equals(checkBox1)) {
slider1.setVisible(checkBox1.isSelected());
menu.setPopupMenuVisible(false);
menu.setPopupMenuVisible(true);
}
}

Call revalidate() it is supposed to do the trick, call it on the newly added components. https://docs.oracle.com/en/java/javase/11/docs/api/java.desktop/java/awt/Component.html#revalidate()
But i would say a use case like this is not what menus are meant for? why not use a dialog for dynamic components?
For background https://docs.oracle.com/en/java/javase/11/docs/api/java.desktop/java/awt/Component.html#revalidate() call it o the newly added component and see https://docs.oracle.com/en/java/javase/11/docs/api/java.desktop/java/awt/Component.html#invalidate() and https://docs.oracle.com/en/java/javase/11/docs/api/java.desktop/java/awt/Container.html#isValidateRoot()

JMenuItem set alignment & maximumsize

I'm trying to make a help button on a JMenuBar. Currently I can make it align to right using this
helpItem.setComponentOrientation(ComponentOrientation.RIGHT_TO_LEFT);
The issue is that it takes up the entire space of the JMenuBar so you can basically press anywhere on the empty space of the JMenuBar and it will press that button. I fixed that by overriding the size of the JMenuItem using this
JMenuItem helpItem = new JMenuItem() {
#Override
public Dimension getMaximumSize() {
Dimension d1 = super.getPreferredSize();
Dimension d2 = super.getMaximumSize();
d2.width = d1.width;
return d2;
}
};
However, after I override getMaximumSize, setComponentOrientation doesn't align the JMenuItem to the right.
EDIT (Current code):
private void createMenuBar() {
JMenuBar newMenuBar = new JMenuBar();
newMenuBar.setName("");
JMenu newMenu = new JMenu("Menu");
JMenuItem updateItem = new JMenuItem("Update");
JMenuItem aboutMe = new JMenuItem("About");
JMenuItem exitItem = new JMenuItem("Exit");
JMenuItem helpItem = new JMenuItem();
URL iconPath = getClass().getResource("/help.png");
helpItem.setIcon(new ImageIcon(iconPath));
addMenuItemActionListeners(updateItem, aboutMe, exitItem, helpItem);
newMenu.add(updateItem);
newMenu.add(aboutMe);
newMenu.add(exitItem);
newMenuBar.add(newMenu);
newMenuBar.add(Box.createHorizontalGlue());
newMenuBar.add(helpItem);
this.setJMenuBar(newMenuBar);
}

There is no need to manually set the component size, avoid it because it's a bad practice and could break your layout.
If you just want to align the help menu on the right, you can make use of Box.createHorizontalGlue method.
Yuo can add all the other menus you're gonna use (of course, if you need), then add the glue, and then add all the other menus you want to have aligned to the right side.
This is an example:
And this is a MCVE to achieve the above result:
import javax.swing.Box;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.SwingUtilities;
public class GlueMenuBarTest
{
public static void main (String [] a) {
SwingUtilities.invokeLater (new Runnable () {
#Override public void run () {
createAndShowGUI ();
}
});
}
private static void createAndShowGUI () {
JFrame frame = new JFrame ("Test");
frame.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);
frame.setJMenuBar (createGlueMenuBar ());
frame.setSize (500, 250); // just for convenience, use pack () in a real app.
frame.setLocationRelativeTo (null);
frame.setVisible (true);
}
private static JMenuBar createGlueMenuBar () {
JMenuBar menuBar = new JMenuBar ();
menuBar.add (new JMenu ("File"));
menuBar.add (new JMenu ("Edit"));
menuBar.add (new JMenu ("Search"));
menuBar.add (Box.createHorizontalGlue ());
menuBar.add (new JMenu ("Help"));
return menuBar;
}
}
If you comment the lines where i add other menus on the left, it will work as well.

How Do i add a jTextArea using menu bar

I am creating a word processor for my own use.I want to add a JTextArea to the frame after i click "NEW" in the menu bar. I am using GUI programing in netbeans.

It'll be hard to answer your question without your source code but here is a working solution (Assuming that by menu bar button you mean a JMenuBar with a JMenuItem):
import java.awt.event.*;
import javax.swing.*;
class WordProcessor extends JFrame implements ActionListener{
JMenuBar menuBar;
JMenu file;
JMenuItem newFile;
JTextArea textArea; //The text area object
public WordProcessor(){
super("WordProcessor");
setSize(400, 400);
setDefaultCloseOperation(EXIT_ON_CLOSE);
setVisible(true);
menuBar = new JMenuBar();
file = new JMenu("File");
newFile = new JMenuItem("new");
file.add(newFile);
menuBar.add(file);
setJMenuBar(menuBar);
textArea = new JTextArea(5, 37); //Instantiate text area object
newFile.addActionListener(this); //listen for events on the 'new' item of the 'file' menu
}
public void actionPerformed(ActionEvent event){
if(event.getSource() == newFile){
add(textArea); //Add the text area to the JFrame if the 'new' item is clicked
}
}
public static void main(String[] args){
WordProcessor window = new WordProcessor();
}
}
This answers your request however I wouldn't add a JTextArea object to the window every time you click the new file menu item, instead I would add the JTextArea on load up and just clear the text area every time they click the new file menu item:
if(event.getSource() == newFile){
textArea.setText(" ");
}

invisible JMenuBar, Accelerator not working

My Program has a JMenuBar with JMenuItems.
They have a ActionListener, and I set a Shortcut with setAccelerator.
Now I am hiding the menu bar when the window become unfocused, to get more space for a displayed image.
But after the first hiding of the menubar, the hotkeys just stop working.
How can I fix that?
I created a little example code to illustrate that strange behavior:
import javax.swing.*;
import java.awt.event.*;
class Example extends JFrame{
public static void main(String[] args) {
new Example(); //main is static
}
static JMenuBar menubar; //be accessable for the ActionListener
Example() {
//JPanel
this.setSize(50,50);
this.setVisible(true);
//Menubar, static
menubar = new JMenuBar();
this.setJMenuBar(menubar);
//Menu
JMenu filemenu = new JMenu("File");
menubar.add(filemenu);
//Item
JMenuItem menuitem = new JMenuItem("Do Something...");
filemenu.add(menuitem);
menuitem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_D, KeyEvent.SHIFT_DOWN_MASK)); // Shift + D
menuitem.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
System.out.println("Action!");
}
});
JButton button = new JButton("Show/Hide menubar");
this.add(button);
button.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
System.out.println("Toggle Bar!");
menubar.setVisible(!menubar.isVisible()); //Toggle
}
});
}
}
For reference:
I'm using Java 1.7.0_60-ea (Java 7) on a Mac.
But this error occurs independent of using the Mac native menu bar or the normal java menu bar inside the JFrame.

You could try to add global keybindings. How to add keybindings is explained here.
Here is an example of what you could do:
//Any component that is always visible in the window (like the image)
JComponent c;
//Get input and action map
InputMap imap = c.getInputMap(WHEN_IN_FOCUSED_WINDOW);
ActionMap amap = c.getActionMap();
//Put keybinding and action
imap.put(KeyStroke.getKeyStroke("shift D"), "doSomething");
amap.put("doSomething", anAction);
Note that it only works in the focused window. But should work regardless of the menubar being visible or not.

Focus on first jmenubar item on "alt" key press

Is there any way to auto-select a jmenu within my jmenubar when the user's pressing the "ALT" key ? (Like windows softwares)
The problem is that the default behavior of my jframe, when the "ALT" key is pressed, is to show up a menu containing the following actions : restore, move, size, reduce, ...
What I want my java application to do, is to select my jmenu first item when "alt" is pressed.
(Like it would do with a mnemonic : "alt + f")

Add the action to the ActionMap and InputMap of your JRootPane. See below:
import java.awt.event.*;
import java.util.*;
import javax.swing.*;
public class MenuExample {
private void setupMenuKey(final JFrame frame) {
Action menuAction = new AbstractAction() {
#Override
public void actionPerformed(ActionEvent e) {
JRootPane rootPane = frame.getRootPane();
JMenuBar jMenuBar = rootPane.getJMenuBar();
JMenu menu = jMenuBar.getMenu(0);
menu.doClick();
}
};
JRootPane rootPane = frame.getRootPane();
ActionMap actionMap = rootPane.getActionMap();
final String MENU_ACTION_KEY = "expand_that_first_menu_please";
actionMap.put(MENU_ACTION_KEY, menuAction);
InputMap inputMap = rootPane.getInputMap(JComponent.WHEN_ANCESTOR_OF_FOCUSED_COMPONENT);
inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_ALT, 0, true), MENU_ACTION_KEY);
}
private JFrame build() {
JFrame frame = new JFrame("Hello");
frame.setSize(300, 300);
JMenuBar bar = new JMenuBar();
List<String> letters = Arrays.asList("A", "B", "C");
for (int i = 0; i < 3; i++) {
JMenu menu = new JMenu("Menu " + i);
for (String string : letters) {
menu.add(new JMenuItem(String.format("Menu %s - %s", i, string)));
}
bar.add(menu);
}
frame.setJMenuBar(bar);
JButton b = new JButton("click");
JPanel p = new JPanel();
p.add(b);
frame.add(p);
setupMenuKey(frame);
return frame;
}
public static void main(String[] args) {
MenuExample menuExample = new MenuExample();
JFrame frame = menuExample.build();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
}

Use actionmap and inputmap of JComponent to do this job. Since JFrame is not a descendant of JCompoenent i would suggest you adding JPanel to your jframe and then,
Action action = new AbstractAction() {
#Override
public void actionPerformed(ActionEvent e) {
jMenu1.doClick();
}
};
jPanel1.getActionMap().put("myAction", action);
jPanel1.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke(KeyEvent.VK_ALT, KeyEvent.ALT_DOWN_MASK), "myAction");

I've found the response very useful, but also with a drawback.
Imagine you're using Cross PlatForm L&F (Metal) and you've defined mnemonics to all the menus; you know that those menus are invoked against pressing . So, if we put the solution provided by black panda the results on a pressing are first we watch the desired menu deployed but immediately after switches to the first menu.
I think that the best way would be on ALT pressing only the first menu should be selected but without showing its contents (Those contents shoud appear on a down key pressing). Is there any way to do this in Cross Platform L&F?.
Alternatively there is another way to proceed without any extra code. If we invoke the System L&F (Windows in my case) the ALT key behaves as desired. See stackoverflow question 13474555 for details.

I have found just by using frame.setJMenuBar(jmenubar); where frame is your JFrame and jmenubar is your JMenuBar, it'll automatically do this. You don't even have to add it to your layout manager.