Develop Reference

How can I switch between jpanels?

I'm still very new to java programming, so please help me to correct any mistakes I might have overlooked or give tips on how to improve this program.
Okay, so a lot of problems have been solved, and now I have a CardLayout, but I still have questions about how I should make my pipes show inside it.
When I tried to add in my refresh rate timer and my speed timer, I have problems about how I need to declare and initialize boolean variables.
Also, when I compile and run this game, I get files such as Game$1.class. Is there a way for me to clean this up, and could someone explain why this happens? Do these have an affect on the finished product? (When the game is compiled and packaged into a JAR.)
I want to set playerIsReady to true when the play button is clicked. And from there, when the if statement is true, then switch to a panel that displays the pipes, and start moving the pipe across the screen. Preferably 3 instances of that pipe, each starting at different times, but whatever you can help with is fine.
Some of this code needs work, so I have commented some parts out and left notes.
My other questions about this game can be found here.
This is my current code
Game.java
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
import javax.swing.border.EmptyBorder;
import javax.swing.SwingUtilities;
public class Game {
public static void main(String[] args) {
Runnable r = new Runnable() {
#Override
public void run() {
// the GUI as seen by the user (without frame)
final CardLayout cl = new CardLayout();
final JPanel gui = new JPanel(cl);
// remove if no border is needed
gui.setBorder(new EmptyBorder(10,10,10,10));
JPanel menu = new JPanel(new GridBagLayout());
JButton playGame = new JButton("Play!");
ActionListener playGameListener = new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
cl.show(gui, "game");
}
};
playGame.addActionListener(playGameListener);
Insets margin = new Insets(20, 50, 20, 50);
playGame.setMargin(margin);
menu.add(playGame);
gui.add(menu);
cl.addLayoutComponent(menu, "menu");
final JPanel pipes = new Pipes();
gui.add(pipes);
cl.addLayoutComponent(pipes, "game");
JFrame f = new JFrame("Pipes Game");
f.add(gui);
// Ensures JVM closes after frame(s) closed and
// all non-daemon threads are finished
f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
// See https://stackoverflow.com/a/7143398/418556 for demo.
f.setLocationByPlatform(true);
// ensures the frame is the minimum size it needs to be
// in order display the components within it
f.pack();
// should be done last, to avoid flickering, moving,
// resizing artifacts.
f.setVisible(true);
/*if (playerIsReady) {
Timer speed = new Timer(10, new ActionListener() { //pipe speed
#Override
public void actionPerformed(ActionEvent e) {
pipes.move();
}
});
speed.start();
Timer refresh = new Timer(30, new ActionListener() { //refresh rate
#Override
public void actionPerformed(ActionEvent e) {
pipes.repaint();
}
});
refresh.start();
}*/
}
};
// Swing GUIs should be created and updated on the EDT
// http://docs.oracle.com/javase/tutorial/uiswing/concurrency
SwingUtilities.invokeLater(r);
}
}
Pipes.java
// What import(s) do I need for ArrayList?
public class Pipes {
List<Pipe> pipes = new ArrayList<Pipe>();
public Pipes() {
pipes.add(new Pipe(50, 100));
pipes.add(new Pipe(150, 100));
pipes.add(new Pipe(250, 100));
}
protected void paintComponent(Graphics g) {
super.paintComponent(g);
for ( Pipe pipe : pipes ){
pipe.drawPipe(g);
}
}
}
PipeObject.java
import java.awt.Graphics;
public class PipeObject {
//Declare and initialiaze variables
int x1 = 754; //xVal start
int x2 = 75; //pipe width
//total width is 83
int y1 = -1; //yVal start
int y2 = setHeightVal(); //pipe height
int gap = 130; //gap height
public void drawPipe(Graphics g) {
g.clearRect(0,0,750,500); //Clear screen
g.drawRect(x1,y1,x2,y2); //Draw part 1
g.drawRect(x1-3,y2-1,x2+6,25); //Draw part 2
g.drawRect(x1-3,y2+25+gap,x2+6,25); //Draw part 3
g.drawRect(x1,y2+25+gap+25,x2,500-y2-49-gap); //Draw part 4
}
public void move() {
x1--;
}
public int getMyX() { //To determine where the pipe is horizontally
return x1-3;
}
public int getMyY() { //To determine where the pipe is vertically
return y2+25;
}
public int setHeightVal() { //Get a random number and select a preset height
int num = (int)(9*Math.random() + 1);
int val = 0;
if (num == 9)
{
val = 295;
}
else if (num == 8)
{
val = 246;
}
else if (num == 7)
{
val = 216;
}
else if (num == 6)
{
val = 185;
}
else if (num == 5)
{
val = 156;
}
else if (num == 4)
{
val = 125;
}
else if (num == 3)
{
val = 96;
}
else if (num == 2)
{
val = 66;
}
else
{
val = 25;
}
return val;
}
}

The best way to approach this is using a CardLayout.
Notes
A button with an ActionListener is far better than a MouseListener over a rectangle.
The button will show focus when the mouse is pointed at it, or the component is tabbed to via the keyboard.
The button is keyboard accessible.
The button has facility to support multiple icons built in (e.g. for 'initial look', focused, pressed etc.)
White space in the GUI is provided around the menu panel and game by adding an EmptyBorder
The button is made larger by setting a margin.
Adjust margins, borders and preferred size according to need. These sizes were set by me so as not to make the screenshots too large.
See more tips in the code comments.
Code
Here is the MCTaRE (Minimal Complete Tested and Readable Example) that produced the above screenshots.
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
import javax.swing.border.EmptyBorder;
public class PipesGame {
public static void main(String[] args) {
Runnable r = new Runnable() {
#Override
public void run() {
// the GUI as seen by the user (without frame)
final CardLayout cl = new CardLayout();
final JPanel gui = new JPanel(cl);
// remove if no border is needed
gui.setBorder(new EmptyBorder(10,10,10,10));
JPanel menu = new JPanel(new GridBagLayout());
JButton playGame = new JButton("Play!");
ActionListener playGameListener = new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
cl.show(gui, "game");
}
};
playGame.addActionListener(playGameListener);
Insets margin = new Insets(20, 50, 20, 50);
playGame.setMargin(margin);
menu.add(playGame);
gui.add(menu);
cl.addLayoutComponent(menu, "menu");
JPanel pipes = new Pipes();
gui.add(pipes);
cl.addLayoutComponent(pipes, "game");
JFrame f = new JFrame("Pipes Game");
f.add(gui);
// Ensures JVM closes after frame(s) closed and
// all non-daemon threads are finished
f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
// See https://stackoverflow.com/a/7143398/418556 for demo.
f.setLocationByPlatform(true);
// ensures the frame is the minimum size it needs to be
// in order display the components within it
f.pack();
// should be done last, to avoid flickering, moving,
// resizing artifacts.
f.setVisible(true);
}
};
// Swing GUIs should be created and updated on the EDT
// http://docs.oracle.com/javase/tutorial/uiswing/concurrency
SwingUtilities.invokeLater(r);
}
}
class Pipes extends JPanel {
Pipes() {
setBackground(Color.BLACK);
setForeground(Color.WHITE);
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawString("Pipes game appears here..", 170, 80);
}
#Override
public Dimension getPreferredSize() {
// adjust to need
return new Dimension(500,150);
}
}

"Is there a way for me to add my GameMenu jpanel to my jframe, and then replace it with the Pipes jpanel?"
As other have suggested, for this you want a CardLayout. It is very simple to you. Personally, I always wrap my CardLayout in a JPanel rather than the JFrame, just force of habit.
What you want to do is have a mainPanel that will have the CardLayout
CardLayout card = new CardLayout();
JPanel mainPanel = new JPanel();
Then you want to add your panels to the mainPanel. What the CardLyaout does is layer the panels, making just one visible at a time. The first one you add, will the in the foreground. Also when you add the panel, you'll also want to issue it a key it can be called from. The key, can be any String you like.
mainPanel.add(gameMenu, "menu");
mainPnael.add(pipes, "pipe");
Now gameMenu is the only panel shown. To show pipes, all you do is use this method
public void show(Container parent, String name) - Flips to the parent that was added to this layout with the specified name, using addLayoutComponent. If no such component exists, then nothing happens.
So you'd use, card.show(mainPanel, "pipes");
Whatever even you want to trigger the showing of pipes, just add that line in that event handler. You could add a button or something to the GameMenu that will allow movement to the Pipes panel.

This works with a mouse click on the menu. You can change it later, to a click on some button or whatever you want.
I added a MouseListener to the Game class. When the user presses the mouse on the menu JPanel, it adds the Pipes JPanel to JFrame and calls the pack method.
Game.java:
import java.awt.Point;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.geom.Rectangle2D;
import javax.swing.JFrame;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
public class Game {
GameMenu menu = new GameMenu();
Pipes game;
boolean start = false;
JFrame f;
Rectangle2D menuRect = new Rectangle2D.Double(20, 20, 60, 40);
public Game() {
f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.add(menu);
f.setTitle("Pipe Game");
f.setResizable(false);
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
menu.addMouseListener(new MouseAdapter() {
#Override
public void mousePressed(MouseEvent e) {
Point click = new Point(e.getX(), e.getY());
System.out.println("Clicked on the Panel");
if(menuRect.contains(click))
{
System.out.println("Clicked inside the Rectangle.");
start = true;
menu.setVisible(false);
game = new Pipes();
f.add(game);
f.pack();
Timer timer = new Timer(10, new ActionListener() { //pipe speed
#Override
public void actionPerformed(ActionEvent e) {
game.move();
}
});
timer.start();
Timer refresh = new Timer(30, new ActionListener() { //refresh rate
#Override
public void actionPerformed(ActionEvent e) {
game.repaint();
}
});
refresh.start();
}
}
#Override
public void mouseReleased(MouseEvent e) {
}
});
}
public static void main(String args[]) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new Game();
}
});
}
}

Why won't my content pane show up on my JFrame?

This is my graphics class, but when I create and add a JPanel as a content pane to it nothing shows up. I have done many tests to see if my content pane is visible but it still will not show.
import java.awt.Color;
import java.awt.Font;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class GraphicsMain extends JFrame{
public static final long serialVersionUID = 7610350056926018727L;
static GraphicsMain frame = new GraphicsMain();
static final int WIDTH = 1024, HEIGHT = 768;
static Listener listener = new Listener();
public static void init() {
createGUI();
}
public static void createGUI() {
frame.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
frame.setFocusable(true);
frame.setLayout(null);
frame.setResizable(false);
frame.setSize(WIDTH, HEIGHT);
frame.setTitle("Game of Life");
frame.setContentPane(frame.createMainPanel());
frame.setVisible(true);
}
public JPanel createMainPanel() {
JPanel totalGUI = new JPanel();
totalGUI.setSize(HEIGHT, WIDTH);
totalGUI.setBackground(Color.red);
totalGUI.setLayout(null);
JPanel buttonPanel = createButtonPanel();
totalGUI.add(buttonPanel);
totalGUI.setVisible(true);
System.out.println("Is returning!");
return totalGUI;
}
public JPanel createButtonPanel() {
JPanel buttonPanel = new JPanel();
buttonPanel.setSize(WIDTH, HEIGHT);
buttonPanel.setLocation(0, 0);
Font buttonFont = new Font("Button Font", Font.PLAIN, 12);
JButton goButton = createButton("Go", WIDTH/16, HEIGHT/12, 10, 10, listener, buttonFont, Color.black);
buttonPanel.add(goButton);
JButton clearButton = createButton("Clear", WIDTH/16, HEIGHT/12, 10 + HEIGHT/12, 10, listener, buttonFont, Color.black);
buttonPanel.add(clearButton);
JButton exitButton = createButton("Exit", WIDTH/16, HEIGHT/12, 10 + 2*HEIGHT/12, 10, listener, buttonFont, Color.black);
buttonPanel.add(exitButton);
return buttonPanel;
}
public JButton createButton(String text, int width, int height, int x, int y, ActionListener listener, Font font, Color color) {
JButton button = new JButton(text);
button.setSize(width, height);
button.setLocation(x, y);
button.addActionListener(listener);
button.setFont(font);
button.setForeground(Color.red);
return button;
}
}
this class is called by
import javax.swing.SwingUtilities;
public class GameOfLifeMain {
static boolean running = true;
static int UPS = 60;
static GameOfLifeMain main = new GameOfLifeMain();
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
main.init();
long startTime = System.nanoTime();
double ns = 1000000000.0 / UPS;
double delta = 0;
long secondTimer = System.nanoTime();
while(running) {
long now = System.nanoTime();
delta += (now - startTime) / ns;
startTime = now;
while(delta >= 1) {
main.update();
delta--;
}
main.render();
if(System.nanoTime() - secondTimer > 1000000000) {
secondTimer += 1000000000;
}
}
}
});
}
public void init() {
GraphicsMain.init();
}
public void update() {
}
public void render() {
//GraphicsMain.render();
}
}

Your problems are (at least) two fold:
As #Radiodef astutely notes, you're calling a long-running loop on the Swing event thread. Since this thread is completely responsible for the rendering of your GUI and the interacting with the user, your GUI becomes completely frozen.
You are using null layouts which make you completely responsible for the positioning and size of all components added to the null-layout using component.
I suggest:
As #Radiodef suggests, do your long-running loop in a background thread such as a SwingWorker. This will allow easier interaction between your GUI and the background process. His link is a good one: Concurrency in Swing.
Use nested JPanels, each one using its own layout to achieve the layout desired, one that will run well on any platform and on any video card setting.
Better to override your drawing JPanels getPreferredSize(...) method to have it sized correctly.
Setting a JPanel to opaque via setOpaque(true) will not help since JPanels are already opaque by default.
Edit
I stand corrected on the last point per Jan Bodnar:
"However, the default value for this property on most standard JComponent subclasses (such as JButton and JTree) is look-and-feel dependent." For example, the JPanel of the GTK look and feel is not opaque by default.
Thanks, Jan

Call setOpaque(true) on your Panel, then the background will be painted. I also noticed that you mixed up WIDTH and HEIGHT when defining the size of your panel (this might be an error).

JButton and JLabel dissappears when adding custom background

JButton and JLabel disappears when adding custom background. I don't see any problems in my program, but maybe you guys find an solution! I think it's only a little thing I forgot, but I can't figure it out.
Here's the code:
GameWindow.java:
setContentPane(new StartImagePanel(RollrackLogo));
out.println("adding JLWelcome");
JLWelcome.setText("Welcome to Rollrack, " + namewindow.name);
add(JLWelcome);
JLWelcome.setVisible(true);
out.println("JLWelcome added");
out.println("adding JBRandom");
JBRandom.setText("Random");
add(JBRandom);
JBRandom.setVisible(true);
out.println("added JBRandom");
The background appears perfect, but not the JButton and JLabel!
Code to the StartImagePanel.java:
public class StartImagePanel extends JComponent{
private Image image;
public StartImagePanel(Image image) {
this.image = image;
}
#Override
protected void paintComponent(Graphics g) {
g.drawImage(image, 0, 0, null);
}
}

Your button and label are added to your GameWindow frame while they should be added to its contentPane, setContentPane(new StartImagePanel(RollrackLogo)); instead. That's why they are not showing, they are added to the frame.
Make a variable of the StartImagePanel and add the button and label to it and they should show up.
StartImagePanel contentPanel = new StartImagePanel(RollrackLogo);
setContentPane(contentPanel);
...
out.println("adding JLWelcome");
JLWelcome.setText("Welcome to Rollrack, " + namewindow.name);
contentPanel.add(JLWelcome);
JLWelcome.setVisible(true);
out.println("JLWelcome added");
out.println("adding JBRandom");
JBRandom.setText("Random");
contentPanel.add(JBRandom);
JBRandom.setVisible(true);
out.println("added JBRandom");
Answer dispute
The claims in the first paragraph are plain wrong. Here is source that proves it.
import java.awt.*;
import javax.swing.*;
import javax.swing.border.EmptyBorder;
public class AddToCustomContentPane {
public static void main(String[] args) {
Runnable r = new Runnable() {
#Override
public void run() {
// the GUI as seen by the user (without frame)
JPanel gui = new JPanel(new FlowLayout());
gui.setBorder(new EmptyBorder(2, 3, 2, 3));
gui.setBackground(Color.RED);
JFrame f = new JFrame("Demo");
f.setContentPane(gui);
// Acid test. Can we add buttons direct to the frame?
f.add(new JButton("Button 1"));
f.add(new JButton("Button 2"));
// Ensures JVM closes after frame(s) closed and
// all non-daemon threads are finished
f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
// See http://stackoverflow.com/a/7143398/418556 for demo.
f.setLocationByPlatform(true);
// ensures the frame is the minimum size it needs to be
// in order display the components within it
f.pack();
// should be done last, to avoid flickering, moving,
// resizing artifacts.
f.setVisible(true);
}
};
// Swing GUIs should be created and updated on the EDT
// http://docs.oracle.com/javase/tutorial/uiswing/concurrency/initial.html
SwingUtilities.invokeLater(r);
}
}
Edit after the custom panel code was given
Here's a snippet that works to show both button and label on a black image background, I removed that was not needed (listeners).
public static void main(String[] v) {
class StartImagePanel extends JPanel {
private Image image;
public StartImagePanel(Image image) {
this.image = image;
}
#Override
protected void paintComponent(Graphics g) {
g.drawImage(image, 0, 0, null);
}
}
class GameWindow extends JFrame{
public GameWindow() {
BufferedImage RollrackLogo;
RollrackLogo = new BufferedImage(400,200,BufferedImage.TYPE_INT_RGB);
final JButton JBRandom = new JButton();
final JLabel JLWelcome = new JLabel();
setDefaultCloseOperation(EXIT_ON_CLOSE);
StartImagePanel panel = new StartImagePanel(RollrackLogo);
setContentPane(panel);
setExtendedState(MAXIMIZED_BOTH);
setVisible(true);
JLWelcome.setText("Welcome to Rollrack");
panel.add(JLWelcome);
JLWelcome.setVisible(true);
JBRandom.setText("Random");
panel.add(JBRandom);
JBRandom.setVisible(true);
}
}
GameWindow window = new GameWindow();
window.pack();
window.setVisible(true);
}

I rather use an instance of a JFrame, instead of extending it, as #Andrew Thompson suggested in another question.
However, if you're extending it, it might be a good practice to call super() in the constructor.
Additionally, we may need to know what is going on in your StartImagePanel.
It seems, to me, to be the problem.
Ensure both your GameWindow and StartImagePanel extend properly their superclasses (call super();).
Ensure your StartImagePanel has a proper Layout.
Add your components before you set your frame visible. This also means you won't need JLWelcome.setVisible(true);.
Ensure that your code is executed in the EDT (Event-Dispatch Thread).
Example:
import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.*;
#SuppressWarnings("serial")
public class GameWindow extends JFrame{
BufferedImage rollrackLogo;
JButton jbRandom;
JLabel jlWelcome;
public GameWindow() {
super();
jbRandom = new JButton("Random");
jlWelcome = new JLabel("Welcome to Rollrack, " +
namewindow.name);
rollrackLogo = new BufferedImage(400, 200,
BufferedImage.TYPE_INT_RGB);
setDefaultCloseOperation(EXIT_ON_CLOSE);
setContentPane(new StartImagePanel(rollrackLogo));
// Add your components.
add(jlWelcome);
add(jbRandom);
addKeyListener(new KeyListener() {
#SuppressWarnings("static-access")
#Override
public void keyPressed(KeyEvent e) {
if(e.getKeyCode() == e.VK_ESCAPE){
System.exit(7);
}
}
#Override
public void keyReleased(KeyEvent arg0) {}
#Override
public void keyTyped(KeyEvent arg0) {}
});
// Pack, or otherwise set fullscreen.
pack();
// Now, set frame visible.
setVisible(true);
}
}
Edit: Now that you've posted the code for your StartImagePanel, I see that you're extending JComponent. Follow my previous advice, (call super), set a Layout, and extend JPanel instead.

Detecting when JSplitPane divider is being dragged, not component being resized

I want to implement a JSplitPane (horizontal split) where the right component has a constant width i.e. when the divider is dragged it will jump back to the correct size, unless the divider is dragged far enough right in which case the right most component will have zero width.
To re-display the right component the user can then drag the divider far enough to the left.
I've got this mostly working, but when I resize the window depending on how much and how fast I change the window size the divider jumps reveal or hide the right component, where as what I want is that it should not change 'state' ie if the right component was not visible then it should remain invisible and vice versa.
I've tried heaps of things but the main obstacle is that there seems to be no way of knowing weather the divider was dragged by the user via mouse or if the code (my divider logic and/or JSplitPane internal logic) changed the divider position.
Here is a self contained test case, run it and try to drag the horizontal divider to hide and reveal the right side panel and with those hidden/shown try to resize the window.
Does not work as intended on Mac OS X Java 1.6 (Apple) or Java 7 (Oracle). With the Oracle stuff the rendering is much slower and the problem is more severe. Resizing the window slowly works, but fast window size changes cause problems.
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Rectangle;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.ComponentEvent;
import java.awt.event.ComponentListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import javax.swing.*;
import net.miginfocom.swing.MigLayout;
public class SplitTest {
public static class MySplitPane extends JSplitPane {
boolean m_RightCollapsed;
public MySplitPane(int orientation, JComponent left, JComponent right) {
super(orientation, left, right);
addPropertyChangeListener(new PropertyChangeListener() {
#Override
public void propertyChange(PropertyChangeEvent evt) {
}
});
addComponentListener(new ComponentListener() {
#Override
public void componentShown(ComponentEvent e) {
reposDivider();
}
#Override
public void componentResized(ComponentEvent e) {
reposDivider();
}
#Override
public void componentMoved(ComponentEvent e) {
reposDivider();
}
#Override
public void componentHidden(ComponentEvent e) {
}
});
}
public void reposDivider() {
setDividerLocation(getDividerLocation());
}
public void setDividerLocation(int location) {
int newLocation;
m_RightCollapsed = location > getSize().width - getRightComponent().getPreferredSize().width / 2;
if (m_RightCollapsed)
newLocation = getSize().width;
else
newLocation = getSize().width - getInsets().right - getDividerSize() - getRightComponent().getPreferredSize().width;
super.setDividerLocation(newLocation);
}
}
static class MyScrollable extends JPanel implements Scrollable {
int m_Height;
public MyScrollable(int height) {
m_Height = height;
}
#Override
public void paint(java.awt.Graphics g) {
super.paint(g);
g.setColor(Color.CYAN);
g.fillOval(0, 0, getWidth(), 500);
}
#Override
public Dimension getPreferredScrollableViewportSize() {
//return super.getPreferredSize();
return new Dimension(100, m_Height);
}
#Override
public int getScrollableUnitIncrement(Rectangle visibleRect, int orientation, int direction) {
// TODO Auto-generated method stub
return 10;
}
#Override
public int getScrollableBlockIncrement(Rectangle visibleRect, int orientation, int direction) {
return 20;
}
#Override
public boolean getScrollableTracksViewportWidth() {
return true;
}
#Override
public boolean getScrollableTracksViewportHeight() {
return false;
}
}
public static class ShrinkGrow extends JPanel {
public ShrinkGrow(final JComponent component, final JSplitPane split) {
JButton grow = new JButton("+++");
JButton shrink = new JButton("---");
add(grow);
add(shrink);
grow.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
Dimension oldSize = component.getPreferredSize();
Dimension newSize = new Dimension(oldSize.width, oldSize.height + 10);
component.setPreferredSize(newSize);
component.setSize(newSize);
}
});
shrink.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
Dimension oldSize = component.getPreferredSize();
Dimension newSize = new Dimension(oldSize.width, oldSize.height - 10);
component.setPreferredSize(newSize);
component.setSize(newSize);
}
});
}
}
public static void main(String[] args) {
JFrame window = new JFrame();
JPanel mainView = new JPanel();
JPanel top = new JPanel();
top.setLayout(new BoxLayout(top, BoxLayout.Y_AXIS));
JPanel bottom = new JPanel();
bottom.setLayout(new BoxLayout(bottom, BoxLayout.Y_AXIS));
final JSplitPane rightSplit = new JSplitPane(JSplitPane.VERTICAL_SPLIT);
JPanel topContent = new MyScrollable(200);
JPanel topFixed = new ShrinkGrow(topContent, rightSplit);
topFixed.setLayout(new BoxLayout(topFixed, BoxLayout.X_AXIS));
JScrollPane topFlexible = new JScrollPane(topContent);
topFlexible.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED);
topFlexible.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
JPanel bottomContent = new MyScrollable(300);
JPanel bottomFixed = new ShrinkGrow(bottomContent, rightSplit);
bottomFixed.setLayout(new BoxLayout(bottomFixed, BoxLayout.X_AXIS));
JScrollPane bottomFlexible = new JScrollPane(bottomContent);
bottomFlexible.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED);
bottomFlexible.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
mainView.setBackground(Color.red);
topFixed.setBackground(Color.green);
topContent.setBackground(Color.green.darker());
bottomFixed.setBackground(Color.blue);
bottomContent.setBackground(Color.blue.darker());
mainView.setMinimumSize(new Dimension(100, 100));
mainView.setPreferredSize(new Dimension(400, 300));
mainView.setMaximumSize(new Dimension(10000, 10000));
topFixed.setMinimumSize(new Dimension(topFixed.getMinimumSize().width, 30));
topFixed.setPreferredSize(new Dimension(topFixed.getPreferredSize().width, 30));
topFixed.setMaximumSize(new Dimension(topFixed.getMaximumSize().width, 30));
bottomFixed.setMinimumSize(new Dimension(bottomFixed.getMinimumSize().width, 40));
bottomFixed.setPreferredSize(new Dimension(bottomFixed.getPreferredSize().width, 40));
bottomFixed.setMaximumSize(new Dimension(bottomFixed.getMaximumSize().width, 40));
topContent.setPreferredSize(new Dimension(100, 500));
bottomContent.setPreferredSize(new Dimension(100, 400));
top.add(topFixed);
top.add(topFlexible);
bottom.add(bottomFixed);
bottom.add(bottomFlexible);
rightSplit.setLeftComponent(top);
rightSplit.setRightComponent(bottom);
rightSplit.setMinimumSize(new Dimension(0, 0));
final JSplitPane mainSplit = new MySplitPane(JSplitPane.HORIZONTAL_SPLIT, mainView, rightSplit);
window.add(mainSplit);
window.pack();
window.setVisible(true);
}
}

Not sure if possible to catch dragging event, but for sure you can catch propertyChange event. Catching events after you move a JSplitPane‘s divider can be made possible through the PropertyChangeListener JSplitPane class. Make sure you supply the DIVIDER_LOCATION_PROPERTY as the parameter so that this listener will listent to modified divider location events.
If you do not supply this as the first parameter in the addPropertyChangeListener() method, you can always place a conditional statement if the PropertyChangeEvent‘s getPropertyName() method returns dividerLocation as the value.
jSplitPane1.addPropertyChangeListener(JSplitPane.DIVIDER_LOCATION_PROPERTY, new PropertyChangeListener() {
#Override
public void propertyChange(PropertyChangeEvent pce) {
// do here
}
});

Add a MouseListener to the JSplitPane Divider to detect when the divider is being dragged. When dragged, respond to the property change events. Sample:
https://community.oracle.com/thread/1352161?start=0&tstart=0
SplitPaneUI spui = splitPane.getUI();
if (spui instanceof BasicSplitPaneUI) {
// Setting a mouse listener directly on split pane does not work, because no events are being received.
((BasicSplitPaneUI) spui).getDivider().addMouseListener(new MouseAdapter() {
public void mouseClicked(MouseEvent e) {

...unless the divider is dragged far enough right in which case the right
most component will have zero width.
To re-display the right component the user can then drag the divider
far enough to the left.
sounds like all you have to do is disable the splitPane to disable dragging,
then setOneTouchExpandable() to true. you may need to remove one of the 'expandable'
buttons to disable expanding the wrong way

KeyPressed and mousePressed Event in an unfocused Component

What are several ways of detecting a key stroke without the need of focusing on the component that the event was implemented? Here's my idea on this:
Even without focusing on myComponent, upon pressing a key, the action should take part. ** Same question for the mousePressed event. A mouse click will be detected even when not clicking on the component.**
myComponent.addKeyListener( new KeyAdapter() {
#Override
public void keyPressed( KeyEvent e ){
// My action here
}
});
Upon answering Question1, can it also be done even if the application is running on background? Say I have a browser, every time I click or press a key, the given action will be executed.
I also accept suggestions to read as an answer. If your answer would be KeyBinding related, please do elaborate. All answer and comments will be greatly appreciated.
I used JNativeHooks examples here and it works perfectly fine. Any other method by just Java alone?

For the first question, regarding the KeyStroke thingy, I guess you can use KeyBinding instead of using KeyListener, that can give you the desired result, without the focus related issues of the component in question, though within the Java Dimensions.
In the example below, the focus is on the JTextField first, so if you will Press CTRL + D, then the paintAction thingy attached to the CustomPanel will work, even though the focus lies with the JTextField.
Though if you will use the setMnemonic() method for JButton, then the JButton will gain focus and will perform it's own action associated with it, which is to draw Ovals. This you can see by Pressing ALT + C, to see the desired effect. Again to perform the drawing related thingy, both the components in question don't need the focus, but still they respond to the KeyStrokes.
Here is the example code :
import java.awt.*;
import java.awt.event.*;
import java.util.Random;
import javax.swing.*;
public class SSCCE
{
private final int WIDTH = 500;
private final int HEIGHT = 500;
private CustomPanel customPanel;
private JButton circleButton;
private JTextField tfield;
private Random random;
private int mode;
private Action paintAction = new AbstractAction()
{
#Override
public void actionPerformed(ActionEvent ae)
{
mode = random.nextInt(3);
Color color = new Color(random.nextFloat(), random.nextFloat()
, random.nextFloat(), random.nextFloat());
customPanel.setValues(random.nextInt(WIDTH),
random.nextInt(HEIGHT), random.nextInt(WIDTH),
random.nextInt(HEIGHT), color, mode);
}
};
private ActionListener buttonAction = new ActionListener()
{
#Override
public void actionPerformed(ActionEvent ae)
{
Color color = new Color(random.nextFloat(), random.nextFloat()
, random.nextFloat(), random.nextFloat());
customPanel.setValues(random.nextInt(WIDTH),
random.nextInt(HEIGHT), random.nextInt(WIDTH),
random.nextInt(HEIGHT), color, 2);
}
};
public SSCCE()
{
random = new Random();
}
private void displayGUI()
{
JFrame frame = new JFrame("SSCCE");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
JPanel contentPane = new JPanel();
contentPane.setLayout(new BorderLayout(5, 5));
customPanel = new CustomPanel();
customPanel.getInputMap(
JComponent.WHEN_IN_FOCUSED_WINDOW).put(
KeyStroke.getKeyStroke(KeyEvent.VK_D
, InputEvent.CTRL_DOWN_MASK), "paintAction");
customPanel.getActionMap().put("paintAction", paintAction);
JPanel footerPanel = new JPanel();
circleButton = new JButton("Draw Circle");
circleButton.setMnemonic(KeyEvent.VK_C);
circleButton.addActionListener(buttonAction);
tfield = new JTextField(20);
tfield.setText("USELESS, just to get the focus for itself.");
tfield.requestFocusInWindow();
footerPanel.add(tfield);
footerPanel.add(circleButton);
contentPane.add(customPanel, BorderLayout.CENTER);
contentPane.add(footerPanel, BorderLayout.PAGE_END);
frame.setContentPane(contentPane);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String... args)
{
EventQueue.invokeLater(new Runnable()
{
#Override
public void run()
{
new SSCCE().displayGUI();
}
});
}
}
class CustomPanel extends JPanel
{
private final int WIDTH = 500;
private final int HEIGHT = 500;
private int mode = 0;
private Color colorShape;
private int x = 0;
private int y = 0;
private int width = 0;
private int height = 0;
public void setValues(int x, int y, int w, int h, Color color, int mode)
{
this.x = x;
this.y = y;
this.width = w;
this.height = h;
this.colorShape = color;
this.mode = mode;
repaint();
}
#Override
public Dimension getPreferredSize()
{
return (new Dimension(WIDTH, HEIGHT));
}
#Override
protected void paintComponent(Graphics g)
{
super.paintComponent(g);
g.setColor(colorShape);
if (mode == 1)
g.fillRect(x, y, width, height);
else if (mode == 2)
g.fillOval(x, y, width, height);
}
}
Related to mousePressed() thingy, #mKorbel, had presented the whole thingy as usual in a delightful manner.
And regarding your second question, seems like you yourself had done some homework on that. Seems like either using what you showed in your question is the workaround for catching Operating System related events and transfer that to your Java Application or Java Native Interface, I guess might also can work for this.

all JComponent has method dispatchEvent,
you can to redirect mouse & key event from one JComponent to the another
for JButton to use doClick() instead
for example
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Point;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import javax.swing.BorderFactory;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.SwingUtilities;
public class LostMouseEvent {
private JPanel panel1;
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new LostMouseEvent();
}
});
}
public LostMouseEvent() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
panel1 = new JPanel() {
private static final long serialVersionUID = 1L;
#Override
public Dimension getPreferredSize() {
return new Dimension(600, 400);
}
};
JPanel panel2 = new JPanel() {
private static final long serialVersionUID = 1L;
#Override
public Dimension getPreferredSize() {
return new Dimension(500, 300);
}
};
JScrollPane pane = new JScrollPane(panel2);
panel1.setBorder(BorderFactory.createLineBorder(Color.blue));
panel2.setBorder(BorderFactory.createLineBorder(Color.green));
panel1.setLayout(new CircleLayout());
panel1.add(pane);
frame.add(panel1);
MouseListener rml = new RealMouseListener();
panel1.addMouseListener(rml);
MouseListener fml = new FakeMouseListener();
panel2.addMouseListener(fml);
frame.pack();
frame.setVisible(true);
}
});
}
private class RealMouseListener extends MouseAdapter {
#Override
public void mousePressed(MouseEvent me) {
System.out.println(me);
Point point = me.getPoint();
System.out.println(me.getX());
System.out.println(me.getXOnScreen());
System.out.println(me.getY());
System.out.println(me.getYOnScreen());
}
}
private class FakeMouseListener extends MouseAdapter {
#Override
public void mousePressed(MouseEvent me) {
JPanel panel2 = (JPanel) me.getSource();
MouseEvent newMe = SwingUtilities.convertMouseEvent(panel2, me, panel1);
System.out.println(newMe.getX());
System.out.println(newMe.getXOnScreen());
System.out.println(newMe.getY());
System.out.println(newMe.getYOnScreen());
panel1.dispatchEvent(me);
}
}
}