I am trying to make a game in Java where pressing spacebar moves the box in the window. I am using Key Binding to accomplish this task. The problem is that I can't figure out how to use an ActionListener on the box itself, which is a JLabel. Here is the code below:
import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import javax.swing.AbstractAction;
import javax.swing.Action;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
public class Game {
private static JFrame frame = new JFrame();
private static JPanel gamePanel = new JPanel();
private static Action playerAction = new PlayerListener();
private static JLabel box = new JLabel();
private static int x = 250;
private static int y = 250;
public static void main(String[] args) {
frame.add(boxPanel());
frame.setTitle("Block Game");
frame.setSize(500,500);
frame.setLocationRelativeTo(null);
frame.setFocusable(true);
box.addActionListener(playerAction);
frame.setVisible(true);
}
static JPanel boxPanel() {
ImageIcon boxIcon = new ImageIcon("box.png");
box.setIcon(boxIcon);
box.setSize(30,30);
box.setLocation(x,y);
box.getInputMap().put(KeyStroke.getKeyStroke("SPACE"), "doPlayerAction");
box.getActionMap().put("doPlayerAction", playerAction);
gamePanel.setLayout(null);
gamePanel.add(box);
frame.add(gamePanel);
return gamePanel;
}
static class PlayerListener extends AbstractAction {
public void actionPerformed(ActionEvent e) {
System.out.println("SPACEBAR");
}
}
}
I tried changing the box to a JButton and working with that instead, but I have found that "SPACEBAR" only prints out when I click on the box itself. Any help is greatly appreciated. Thanks!
Your "core" problem revolves around box.getInputMap(), change it to something more like box.getInputMap(WHEN_IN_FOCUSED_WINDOW) which will mean that the API will respond to key events whenever the window has focus, regardless what other components might have focus.
I'd also suggestsomething more like box.getInputMap(WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke(KeyEvent.VK_SPACE, 0), "doPlayerAction"), as the mechanism which KeyStroke uses to parse String to a KeyStroke is more complicated then it might seem, normally requiring additional information like pressed, released or typed, it's just easier to use the virtual keys
I would also bind the keys to the gamePanel as a general preference, as it should be the container making decisions about what to do, but that's just me.
Have a look at How to Use Key Bindings for more details
Related
In my program a JPanel component which is operated by listener using KeyBindings (changed that from KeyListeners already after reading about issues with focusing) is added to a JFrame. Task of this app is to simply move drawn figure around using arrow keys.
This works perfectly until i add another component before drawing board (JPanel with three buttons).
I tested both Keybindings and KeyListener and both methods have the same issue.
If I add components after drawing board keybindings starts to work again.
Here is my UI class where i add components.
EDIT: removed uncleaned code
I would like to understand Java a bit more so any answer is very appreciated.
Edit: I cleaned my code and created "minimal" example of the problem.
Thank you Andrew for heads up.
Program should print "movingup" in console after pressing arrow up.
The problem occurs here:
container.add(buttons); //after adding this Key Bindings stops working
container.add(board);
And the question is: Why order of adding components makes Key Bindings to stop working? If i add buttons after board Key Binding is working.
Class with the problem (used for creating frame and adding components)
import java.awt.Container;
import java.awt.Dimension;
import java.awt.GridLayout;
import javax.swing.JFrame;
import javax.swing.KeyStroke;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.WindowConstants;
public class UserInterface implements Runnable {
private static final String MOVE_UP = "moveUP";
private JFrame frame;
public UserInterface() {
}
#Override
public void run() {
frame = new JFrame("Board");
frame.setPreferredSize(new Dimension(500, 400));
frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
frame.setLayout(new GridLayout());
createComponents(frame.getContentPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
private void createComponents(Container container) {
DrawingBoard board = new DrawingBoard();
container.add(new JButton()); //after adding this figure stops moving - arrow keys doesn't work
container.add(board);
MovingUpwards up = new MovingUpwards(board);
board.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW);
board.getInputMap().put(KeyStroke.getKeyStroke("UP"), MOVE_UP);
board.getActionMap().put(MOVE_UP, up);
}
public JFrame getFrame() {
return frame;
}
}
Rest of the used classes for testing purposes:
import javax.swing.SwingUtilities;
public class Main {
public static void main (String[] args) {
UserInterface ui = new UserInterface();
SwingUtilities.invokeLater(ui);
}
}
import java.awt.Color;
import java.awt.Graphics;
import javax.swing.JPanel;
public class DrawingBoard extends JPanel {
public DrawingBoard() {
super.setBackground(Color.WHITE);
}
#Override
protected void paintComponent (Graphics graphics) {
super.paintComponent(graphics);
}
}
import java.awt.Component;
import java.awt.event.ActionEvent;
import javax.swing.AbstractAction;
public class MovingUpwards extends AbstractAction {
private Component component;
public MovingUpwards(Component component) {
this.component = component;
}
#Override
public void actionPerformed(ActionEvent a) {
System.out.println("movingup");
}
}
The key bindings work fine for me. Check out the Motion Using Key Bindings example found in Motion Using the Keyboard.
I changed the code:
frame.add( content );
frame.add(left, BorderLayout.NORTH);
to:
frame.setLayout(new GridLayout());
frame.add(left);
frame.add( content );
to better simulate your logic.
If you need more help then read Andrew's comment above. Simplify your code to demonstrate the problem so we can "easily" test it by copying and compiling a single source file, the way you can test the code found in the link above.
Learning to code, building a GUI to figure out how everything interacts. Trying to write a method to set focus on (component) at the points I need in the larger program - ie to call FocusGrabber(JTextField1) and have it set the input focus on JTextField1. In an attempt to do my best SSCCE, I've made a simple main that makes just enough GUI to give 2 textfields that should set focus on the second.
package ODIN;
import java.awt.Component;
import java.util.List;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;
/*
*/
class FocusGrabber implements Runnable {
private JComponent component;
public FocusGrabber(JComponent component) {
this.component = component;
}
#Override
public void run() {
component.grabFocus();
}
public static void main(String[] args){
//draw and show the GUI
JFrame GUI = new JFrame();
GUI.setTitle("New Provider Interface");
GUI.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
final JTextField textID = new JTextField("providerID ", 20);
final JTextField textName = new JTextField("Provider Name ", 20);
GUI.add(textID);
GUI.add(textName);
GUI.pack();
GUI.setVisible(true);
FocusGrabber(textName);
}
}
Use requestFocusInWindow over grabFocus...
It would also be helpful if you called the run method at some point
Also, shouldn't it be more like
FocusGrabber fg = new FocusGrabber(textName);
fg.run();
I need something really basic.
I tried this:
import java.*;
import javax.swing.*;
import java.awt.Container;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import java.awt.event.ActionEvent;
import javax.swing.JComponent;
import javax.swing.JFrame;
public class thisthing
{
public static void main(String[]args)
{
boolean done = false;
while (!done)
{
JFrame frame = new JFrame();
JButton button= new JButton("Add Interest");
frame.add(button);
JButton button1 = new JButton("Other Button");
frame.add(button1);
class AddInterestListener implements ActionListener
{
public void actionPerformed(ActionEvent event)
{
System.out.println("hello, I was pressed");
}
}
class OtherButtonListener implements ActionListener
{
public void actionPerformed(ActionEvent event)
{
System.out.println("The Other button was pressed");
}
}
ActionListener listener = new AddInterestListener();
button.addActionListener(listener);
ActionListener listener1 = new OtherButtonListener();
button1.addActionListener(listener1);
frame.setSize(100, 100);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
}
}
But then my computer had trouble making two buttons on one window when I ran it, so it tried to make two windows. I really don't know how to describe it except to say that it was a mess and I did something wrong.
In the end I need to add 15 buttons in a triangle shape (the famous AP peg game project)..so is there any way I can also re-position the buttons and mess with their sizes?
You could either (recommended) use another layoutmanager (or define one on your own). Or (really NOT recommended and extremely ugly solution, but it works):
frame.setLayout(null);
JButton button = new JButton("Hello world");
button.setBounds(20 , 20 , 100 , 30);
frame.add(button);
this will position the button at the given location and with the given size. Alternatively you could use
button.setSize(100 , 30);
button.setLocation(20 , 20);
Note: without a layoutmanager, you can position your components freely, but they will by default have the bounds (0 , 0 , 0 , 0), so you will always have to set the position and size to get anything visible. I only provide this solution because you asked for it, you shouldn't use it though.
I am creating a simple Java application using JCanvas, I need to get the key code of a key pressed by the user: The following is a simplified version of the Java Code
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.util.EventObject;
import java.awt.event.*;
// myJavaFiles project contains JCanvas & JEventQueue Classes
import myJavaFiles.*;
import javax.swing.*;
public static void main(String[] args) {
JCanvas canvas = new JCanvas();
JEventQueue events = new JEventQueue();
events.listenTo(canvas, "canvas");
JFrame frame = new JFrame();
frame.setSize(700, 700);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setFocusable(true);
frame.add(canvas);
while (true) {
if (events.hasEvent()){
EventObject event = events.waitEvent();
if(JEventQueue.isKeyPressed(event)){
int keycode = events.getKeyCode(event);
// USE KEYCODE!!!
}
}
canvas.sleep(10);
canvas.clear();
}
}
Everything works, (I omitted a lot of the non relevant code), except for getting the key pressed, I did notice that events.hasEvent doesn't even seem to be true when I press a key!
Please help! What am I doing wrong?
It's a bit difficult without the code for JCanvas and JEventQueue, but normally I would use a key listener for a panel that contains the canvas:
//frame.add(canvas);
final JPanel panel = new JPanel();
panel.add(canvas);
frame.getContentPane().add(panel);
panel.addKeyListener(new KeyAdapter() {
#Override
public void keyPressed(final KeyEvent keyEvent) {
System.out.println("keyEvent.getKeyCode(): " + keyEvent.getKeyCode());
}
});
I am having some problems regarding to the JMenuBar and I cant seem to figure it out.
I will start with an abriviation of the problem: The program consists of a JFrame, a JDialog and a JMenuBar. Initially, you will get to see a JFrame with the JMenuBar in the top. But at some point, the JDialog will pop up where a user can fill in some text fields. The problem that I'm having is that as soon as the focus goes to the JDialog, the JMenuBar disappears. What I want is that the JMenuBar stays in the top of the screen all the time, except if the whole program is NOT in focus. Here are 2 screenshots, in the first screen shot, the JFrame is selected and in the other one the JDialog is selected.
So what i actually want is instead of only seeing the JMenuBar when the focus is on the JFrame, i want to see the JMenuBar all the time. Since a JDialogs can not have the JMenuBar in the top, like a JFrame has, i decided not to have multiple JMenuBars, but just the one that should be visible all the time.
At last i will give a part of the code that is as small as possible (and still working) and also contains the problem:
import java.awt.Dimension;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import javax.swing.JDialog;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JRootPane;
import javax.swing.KeyStroke;
/**
* #author Guus Leijsten
* #created Oct 27, 2012
*/
public class MenuBarProblem extends JFrame {
public MenuBarProblem() {
super("Frame");
this.setMinimumSize(new Dimension(270, 200));
this.setPreferredSize(new Dimension(800, 530));
this.setDefaultCloseOperation(EXIT_ON_CLOSE);
JRootPane root = this.getRootPane();
//Menu
JMenu fileMenu = new JMenu("File");
JMenuItem file_exit = new JMenuItem("Exit");
file_exit.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_W, Toolkit.getDefaultToolkit().getMenuShortcutKeyMask()));
file_exit.setToolTipText("Exit application");
file_exit.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
System.exit(0);
}
});
fileMenu.add(file_exit);
JMenuBar menu = new JMenuBar();
menu.add(fileMenu);
root.setJMenuBar(menu);
this.setVisible(true);
JDialog d = new JDialog(this, "Dialog");
d.setSize(200, 100);
d.setLocation(0, (int)root.getContentPane().getLocationOnScreen().getY());
d.setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
d.setVisible(true);
}
public static void main(String[] args) {
String os = System.getProperty("os.name").toLowerCase();
if(os.indexOf("mac") >= 0) {
System.setProperty("apple.laf.useScreenMenuBar", "true");
}
new MenuBarProblem();
}
}
If I can be honoust, i think that the problem lies in the part of JRootPane. But we'll see ;)
Did anyone else encountered this problem and managed to solve it alrady, or is there anybody that wants to give it a shot?
Thanks in advance!
Added content:
In the following example I will show a version that gives some functionality to the play.
This is the program i'm making:
The second image shows the state in which the right menu is undocked.
Obviously the JMenuBar should still be visible and operational because without it, a lot of functionalities of the program will be disabled.
At this point i'm starting to think that it is impossible for the JMenuBar to stay visible when the dialog (undocked menu) is undocked, and focussed on.
I know that the JMenuBar on a JDialog can not be in the mac osx style (top of screen), so are there any other techniques i can use for undocking, which does give me a mac osx style JMenuBar?
One key to solving this problem, pun intended, is to let a key binding share a common menu action, as shown below. Note how a menu item, your dialog's content and an (otherwise superfluous) button can all use the same Action instance. A few additional notes:
Kudos for using getMenuShortcutKeyMask().
Swing GUI objects should be constructed and manipulated only on the event dispatch thread (EDT).
System properties should be set before starting the EDT.
Make the dialog's setLocation() relative to the frame after its geometry is known.
A common Mac idiom uses the following predicate:
if (System.getProperty("os.name").startsWith("Mac OS X") {…}
See also this example.
For local use in the dialog itself, also consider JToolBar.
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import javax.swing.AbstractAction;
import javax.swing.Action;
import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
/**
* #see https://stackoverflow.com/a/13100894/230513
*/
public class MenuBarProblem extends JFrame {
private static final int MASK =
Toolkit.getDefaultToolkit().getMenuShortcutKeyMask();
private static final String exitName = "Exit";
private static final KeyStroke exitKey =
KeyStroke.getKeyStroke(KeyEvent.VK_W, MASK);
private final ExitAction exitAction = new ExitAction(exitName);
public MenuBarProblem() {
super("Frame");
this.setDefaultCloseOperation(EXIT_ON_CLOSE);
JMenu fileMenu = new JMenu("File");
JMenuItem fileExit = new JMenuItem(exitAction);
fileMenu.add(fileExit);
JMenuBar menu = new JMenuBar();
menu.add(fileMenu);
JDialog d = new JDialog(this, "Dialog");
JPanel p = new JPanel();
p.getInputMap().put(exitKey, exitName);
p.getActionMap().put(exitName, exitAction);
p.add(new JButton(exitAction));
d.add(p);
d.pack();
d.setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
this.setJMenuBar(menu);
this.pack();
this.setSize(new Dimension(320, 240));
this.setLocationByPlatform(true);
this.setVisible(true);
d.setLocation(this.getRootPane().getContentPane().getLocationOnScreen());
d.setVisible(true);
}
private static class ExitAction extends AbstractAction {
public ExitAction(String name) {
super(name);
this.putValue(Action.MNEMONIC_KEY, exitKey.getKeyCode());
this.putValue(Action.ACCELERATOR_KEY, exitKey);
}
#Override
public void actionPerformed(ActionEvent e) {
System.exit(0);
}
}
public static void main(String[] args) {
System.setProperty("apple.laf.useScreenMenuBar", "true");
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
new MenuBarProblem();
}
});
}
}
Solved!
Using a JFrame with the use of setAlwaysOnTop(true) gives me the desired effect of having a JMenuBar when the focus changes.