Develop Reference

Placing an invisible button on top of an Image

I'm making a small java game for fun to practice with my GUI programming. I want to have the center of my content pane's borderLayout be an image, and I would like to put "invisible" buttons on top of the image in specific places (to be placed later, I just want to get one working for now). My issue is getting the button to actually be invisible, it seems to leave a white square where it is now. I looked around but the only things that seem to be suggested were the .setOpaque, .setContentAreaFilled, and .setBorderPainted. (game is space related, explains the names)
galaxyButton1 = new JButton();
galaxyButton1.setFont(starSystem);
galaxyButton1.setBorder(BorderFactory.createEmptyBorder(25,25,25,25) );
galaxyButton1.setOpaque(false);
galaxyButton1.setContentAreaFilled(false);
galaxyButton1.setBorderPainted(false);
Color invis = new Color(Color.TRANSLUCENT);
galaxyButton1.setForeground(invis);
galaxyButton1.setBackground(invis);
galaxyButton1.addActionListener( new ButtonHandler() );
JPanel centerPanel = new JPanel();
centerPanel.setLayout(new BorderLayout());
JPanel buttons = new JPanel();
buttons.setLayout(new GridLayout( 1,0,5,5 ) );
buttons.setOpaque(false);
buttons.add(galaxyButton1);
centerPanel.add(buttons,BorderLayout.CENTER);
centerImg.setLayout(new GridBagLayout());
centerImg.add(centerPanel);
contentPane.add(centerImg, BorderLayout.CENTER);

Here is a code outline of how to make your own button. You will need to set up a the actual mouse in some other class.
public class InvisibleButton implements MouseListener{
private final Rectangle rectangle;
public InvisibleButton(int x, int y, int width, int height){
rectangle = new Rectangle(x,y,width,height);
}
#Override
public void mouseClicked(MouseEvent e) {
int x = 0; // Set this to Mouse X
int y = 0; // Set this to Mouse Y
if(rectangle.contains(x,y)){
//Set Something to True or do action here
}
}
#Override
public void mousePressed(MouseEvent e) {
}
#Override
public void mouseReleased(MouseEvent e) {
}
#Override
public void mouseEntered(MouseEvent e) {
}
#Override
public void mouseExited(MouseEvent e) {
}
}

Displaying JPanel to JFrame another class

I have a main JFrame and three java class that contains different pie charts and these piechart are in panel. I want to call the three pie classes in main jframe. How can l do that?
// I have three of these Chart classes creating different charts inside panels
public class PiePanel extends Observer {
Singleton connCC = Singleton.getInstance();
Connection con = null;
Statement stm = null;
PiePanel(Subject s) {
panel = new JPanel();
sub = s;
}
#Override
public void update() {
try {
con = connCC.getDBconnection();
stm = con.createStatement();
ResultSet rs = stm.executeQuery("Select pet_name as pet, count(pet_ID) AS 'count' from Pet group by pet_name");
DefaultPieDataset dataset = new DefaultPieDataset();
while (rs.next()) {
dataset.setValue(rs.getString("pet"), Integer.parseInt(rs.getString("count")));
}
JFreeChart pieChart = ChartFactory.createPieChart("Header", dataset, true, true, false);
PiePlot plot = (PiePlot) pieChart.getPlot();
plot.setSimpleLabels(true);
PieSectionLabelGenerator gen = new StandardPieSectionLabelGenerator(
"{0}: {1} ({2})", new DecimalFormat("0"), new DecimalFormat("0%"));
plot.setLabelGenerator(gen);
panel.add(new ChartPanel(pieChart) {
#Override
public Dimension getPreferredSize() {
return new Dimension(335, 235);
}
});
panel.validate();
} catch (Exception e) {
JOptionPane.showMessageDialog(null, e);
}
}
//below is a class that puts all the panels inside a list
public class Subject {
private List<Observer> panel = new ArrayList<Observer>();
public Subject(){
panel.add(new BarPanel(this));
panel.add(new AreaPanel(this));
panel.add(new PiePanel(this));
}
public List<Observer> getChart(){
return panel;
}
}
//main
public class Main {
public static void main(String[] args) {
Subject s = new Subject();
while (true) {
String input = JOptionPane.showInputDialog(null, "Input value:");
if ("d".equals(input) || "w".equals(input)) {
try {
//String value = Integer.parseInt(input);
s.setState(input);
} catch (Exception e) {
System.exit(0);
}
} else {
System.out.println("Wrong Input!");
System.exit(0);
}
}
}
}
Now i want to pass this list in another JFrame class just as in the picture.

Your problem is that you're adding three components in a default fashion to a container that uses BorderLayout, and this results in each added component in the BorderLayout.CENTER covering all the other components added previously. If you want to display three components you can:
Use BorderLayout constants to add the components to different locations within the BorderLayout-using container, or
use a different layout, here perhaps a GridLayout(3, 1), or
if you want a more complex GUI that shows more components, then nest JPanels, each using its own layout manager.
For example, if you want to display the pie charts to the side for instance, then I'd put them into a JPanel that uses a GridLayout, and then add that GridLayout using JPanel to the BorderLayout-using main GUI in the BorderLayout.LINE_END position, or whatever location you desire.
If on the other hand your goal is to swap out one JPanel for another in response to an event, then use a CardLayout to allow easy and efficient swapping of components.

Getting JPanel[][] coordinates by clicking on a JPanel

I've created a JPanel[][] Array.
private JPanel[][] pnlFeld;
And filled it with panels
for (int i = 0; i < world.getSize(); i++) {
for (int j = 0; j < world.getSize(); j++) {
pnlFeld[i][j] = new JPanel();
pnlFeld[i][j].setBorder(new EtchedBorder());
pnlFeld[i][j].addMouseListener(ml);
pnlFeld[i][j].setBackground(off);
add(pnlFeld[i][j]);
}
}
Now I want to get the array coordinates ([][]) by clicking on them and I have no clue how to do that.
I've only added methods to change the color of the panel I clicked on, nothing related to my problem.
MouseListener ml = new MouseListener() {
#Override
public void mouseEntered(MouseEvent e) {
if (world.getMode().equals("Malen")) {
if (e.getSource() instanceof JPanel)
e.getComponent().setBackground(on);
// check();
}
else if (world.getMode().equals("Radieren")) {
if (e.getSource() instanceof JPanel)
e.getComponent().setBackground(off);
// check();
}
}
#Override
public void mousePressed(MouseEvent e) {
if (SwingUtilities.isLeftMouseButton(e)) {
if (world.getMode().equals("Setzen")) {
if (e.getSource() instanceof JPanel) {
if (e.getComponent().getBackground() == off) {
e.getComponent().setBackground(on);
} else
e.getComponent().setBackground(off);
}
// check();
}
}
}
#Override
public void mouseClicked(MouseEvent e) {}
#Override
public void mouseExited(MouseEvent e) {}
#Override
public void mouseReleased(MouseEvent e) {}
};

Actually you can use getBounds() to get component location and size. If you mean the array indexes there could be multiple solutions.
Define a Map and place all your panels in the Map with String value e.g. i+":"+j (or define simple pojo class with 2 fields i and j.
Create unique listener for each JPanel to keep the i and j.
Place the panels in a containr with GridBagLayout then you can use gridBagLayoutInstance.getConstraints(theClickedPanel) and check row column of the constraint

Getting JPanel[][] coordinates by clicking on a JPanel
Use a JButton[][] with ActionListener for easier coding and a better user experience. The ActionEvent has a getSource() method that will identify the button that was activated.
This chess GUI uses buttons for the 64 places on the chessboard.

If you create your MouseListener in your loop, you can use i en j within the code of your listener. The drawback is that you'll have a bit more instances of your listener.

I could suggest that you set the name of each JPanel as i and j in the loop where you declare and initialise the panels. As illustrated
pnlFeld[i][j].setName(i + "" + j);
And in your mouseClicked event check if the event source is an instance of JPanel and parse the name to get the x and y coordinates like this:
Integer.parseInt(p.getName().subString(0,1))
Integer.parseInt(p.getName().subString(1));

Multiple JLabel doesn't print on screen

I want to print multiple label according to the number(no string allowed) you wrote in a text field first. I want it to be dynamical. I want it to change every time you type something in the text field.
So far it can read if it's a number or a string and throw exception if the text doesn't match the requirement.
I've try multiple thing to print multiple Jlabel on the screen, but it didn't work so far.
Here's the code: can you help me?
The main window class
public class MainWindow extends JFrame {
private MainPanel mp = new MainPanel();
public MainWindow()
{
this.setVisible(true);
this.setTitle("Calculateur sur 100");
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setSize(200, 400);
this.setLocationRelativeTo(null);
this.setContentPane(mp);
}}
The mainPanel class
public class MainPanel extends JPanel implements ActionListener, MouseListener, KeyListener {
private JTextField tI = new JTextField("Pourcentage");
private JOptionPane jop3 = new JOptionPane();
public MainPanel()
{
this.add(tI);
tI.addKeyListener(this);
tI.addMouseListener(this);
}
//Mathematic calculation
private double onHundred(int tot, int now)
{
return (tot / 100) * now;
}
public void keyReleased(KeyEvent e)
{
boolean ok = true;
try
{
int numbs = Integer.parseInt(tI.getText());
}
catch(Exception s)
{
tI.setText("");
jop3.showMessageDialog(null, "Veuillez entrer seulement des chiffres", "Erreur", JOptionPane.ERROR_MESSAGE);
ok = false;
}
if(ok)
{
System.out.print("Supposed to print");
JLabel[] label = new JLabel[Integer.parseInt(tI.getText())];
for(int i = Integer.parseInt(tI.getText()); i <= 0; i--)
{
label[i] = new JLabel(i + " = " + Math.ceil(onHundred(Integer.parseInt(tI.getText()), i)));
label[i].setVisible(true);
this.add(label[i]);
}
}
}

You MainWindow class should look something like this:
public class MainWindow extends JFrame {
private MainPanel mp = new MainPanel();
public static void main(String[] args) {
new MainWindow();
}
public MainWindow() {
setContentPane(mp);
setTitle("Calculateur sur 100");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
pack();
setLocationRelativeTo(null);
setVisible(true);
}
}
Note the order: setContentPane then pack then setVisible. pack replaces setSize as it determines the preferred size of the window based on its components.
I modified your MainPanel class:
public class MainPanel extends JPanel {
private JTextField tI = new JTextField("Pourcentage");
JPanel labelPanel = new JPanel();
public MainPanel() {
setLayout(new BorderLayout());
tI.getDocument().addDocumentListener(new MyDocumentListener());
add(tI, BorderLayout.PAGE_START);
add(labelPanel);
}
private int check() {
int numL;
try {
numL = Integer.parseInt(tI.getText());
} catch (NumberFormatException exc) {
return 0;
}
return numL > 100? 100 : numL;
}
private void update(int numL) {
labelPanel.removeAll();
for (int i = 0; i < numL; i++)
labelPanel.add(new JLabel(String.valueOf(i+1)));
JFrame mainWindow = ((JFrame) SwingUtilities.getWindowAncestor(this));
mainWindow.pack();
mainWindow.repaint();
}
class MyDocumentListener implements DocumentListener {
#Override
public void insertUpdate(DocumentEvent e) {
update(check());
}
#Override
public void removeUpdate(DocumentEvent e) {
update(check());
}
#Override
public void changedUpdate(DocumentEvent e) {
}
}
}
Explanation:
The main panel has the text field separately from another panel which updates dynamically to contain the labels.
The text field uses a DocumentListener instead of a KeyListener to listen to changes in its contents. This is the correct approach for many reasons I will not get into here unless really necessary.
Whenever the text changes, a check method verifies that the input is a number. If it's not it returns 0. If it's more than 100 it returns 100. You can change this behavior as you need.
The value from check is passed to update which clears all the previous labels and reconstructs them. (You can do a bit of optimization here if you want by keeping labels in memory but not displaying them. If the cap is 100 as in my example this won't be noticeable.). The main frame then recalculates the space it needs for all the labels and then repaints.
The labels appear next to each other because the default layout for JPanel is FlowLayout. You can change this as needed.

First - you have Integer.parseInt(tI.getText()) a number of times within the same keyReleased function. When you have done the first check to assign it to int numbs, then use numbs from then on, instead of referring back to tI.getText(). Theoretically the user input can change while you are processing your array, which will cause runtime exceptions or undesired results. Hint - declare numbs directly under ok.
Second - after you add controls programmatically, you need to invalidate the control on to which you are adding them, ie your MainPanel. The invalidate directive tells the control that it is not drawn correctly and needs to be repainted (do this at the completion of your loop). Look through the documentation for JPanel for invalidate and paint.

Java - How to make the images disappear

Hi I want to make my JPanel disappear so I wrote these lines of code
removeAll();
updateUI();
revalidate();
That only made the JComponents and JButtons disappear. I would like to make the images that I have displayed with the paint method disappear also. If I do setVisible(false), then I cannot add another JPanel behind it.
This is my class:
package screens;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class menuScreen extends JPanel implements MouseListener{
private static final long serialVersionUID = 1L;
//-------------VARIABLES---------------//
Image wallpaper = (Image)Toolkit.getDefaultToolkit().getImage(getClass().getResource("images/wallpaper.jpg"));
Image title_text = (Image)Toolkit.getDefaultToolkit().getImage(getClass().getResource("images/title-text.png"));
ImageIcon startGameimg = new ImageIcon(Toolkit.getDefaultToolkit().getImage(getClass().getResource("images/startGame.png")));
ImageIcon optionsimg = new ImageIcon(Toolkit.getDefaultToolkit().getImage(getClass().getResource("images/options.png")));
//JButton start = new JButton(basketball);
JLabel options = new JLabel(optionsimg);
JLabel startGame = new JLabel(startGameimg);
gameScreen gS = new gameScreen();
CardLayout scenechange = new CardLayout();
JPanel scenechange1 = new JPanel (scenechange);
//-------------PAINT FUNCTION----------//
public void paintComponent(Graphics g){
g.drawImage(wallpaper,0,0,this);
g.drawImage(title_text,0,0,this);
//g.drawImage(basketball1,110,180,this);
}
//-------------CONSTRUCTOR-------------//
public menuScreen(){
scenechange.addLayoutComponent(this,"menuScreen");
scenechange.addLayoutComponent(gS,"gameScreen");
//scenechange.show(this,"menuScreen");
this.setLayout(null);
this.add(options);
this.add(startGame);
startGame.setBounds(110,180,110,110);
options.setBounds(110,300,110,110);
startGame.addMouseListener(this);
options.addMouseListener(this);
}
public void mouseClicked(MouseEvent e) {
if(e.getSource() == (startGame)){
removeAll();
revalidate();
add(gS);
}
if(e.getSource() == (options)){
setVisible(false);
}
}
public void mousePressed(MouseEvent e) {
// TODO Auto-generated method stub
}
public void mouseReleased(MouseEvent e) {
// TODO Auto-generated method stub
}
public void mouseEntered(MouseEvent e) {
// TODO Auto-generated method stub
}
public void mouseExited(MouseEvent e) {
// TODO Auto-generated method stub
}
}//END OF CLASS startingScreen
Thanks in advance.

First, don't call updateUI, it's related to the Look and Feel and not (directly) to updating your components.
If you have provided a custom paint routine within in your panel, then you need away to stop it from painting the images (without preventing it from painting it's own content). removeXxx will remove child components that you have previously added to the container.
A little more code would be useful
UPDATE
Fisrt, the images your painting aren't components of you container, they are been "stamped", you need some way to tell the component not to the paint the images
public void paintComponent(Graphics g){
super.paintComponent(g); // this is super important
if (paintImages){ // you need to define and set this flag
g.drawImage(wallpaper,0,0,this);
g.drawImage(title_text,0,0,this);
}
}
Now, this will stop the images from been painted.
If, however, you no longer want to use the component (ie, you want to remove it from the screen so you can place a new component on the screen in its place), you need to remove this component from it's parent, which Code-Guru has suggested (so I won't steal his answer ;))
UPDATE
Okay, you had a kernel of an idea but either didn't quite know how to implement it or decided to discard it.
Basically, from the looks of your code, you were either trying to, or had, implement a CardLayout, unfortunately, you kind of got the wrong idea with it.
With CardLayout, you need to "controller", a component that is responsible for switching the screens...
public class ScreenController extends JPanel {
private static final long serialVersionUID = 1L;
//-------------VARIABLES---------------//
MenuScreen ms = new MenuScreen();
GameScreen gs = new GameScreen();
CardLayout sceneChange;
//-------------CONSTRUCTOR-------------//
public ScreenController() {
sceneChange = new CardLayout();
this.setLayout(sceneChange);
add(ms, "menuScreen");
add(gs, "gameScreen");
sceneChange.show(this, "menuScreen");
ms.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
if (e.getActionCommand().equalsIgnoreCase("startgame")) {
sceneChange.show(ScreenController.this, "gameScreen");
}
}
});
}
}//END OF CLASS startingScreen
Then you have your menu and game screens...
public class MenuScreen extends JPanel implements MouseListener {
private static final long serialVersionUID = 1L;
//-------------VARIABLES---------------//
//JButton start = new JButton(basketball);
JLabel options = new JLabel("Options");
JLabel startGame = new JLabel(" >> Start << ");
// gameScreen gS = new gameScreen();
BufferedImage wallpaper;
//-------------PAINT FUNCTION----------//
#Override
public void paintComponent(Graphics g) {
System.out.println("paint");
super.paintComponent(g);
if (wallpaper != null) {
g.drawImage(wallpaper, 0, 0, this);
}
}
//-------------CONSTRUCTOR-------------//
public MenuScreen() {
// Please handle your exceptions better
try {
wallpaper = ImageIO.read(getClass().getResource("/Menu.png"));
setPreferredSize(new Dimension(wallpaper.getWidth(), wallpaper.getHeight()));
} catch (IOException ex) {
ex.printStackTrace();
}
setLayout(new GridBagLayout());
Cursor cusor = Cursor.getPredefinedCursor(Cursor.HAND_CURSOR);
options.setCursor(cusor);
startGame.setCursor(cusor);
Font font = UIManager.getFont("Label.font").deriveFont(Font.BOLD, 48);
options.setFont(font);
startGame.setFont(font);
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridx = 0;
gbc.gridy = 0;
this.add(options, gbc);
gbc.gridy++;
this.add(startGame, gbc);
startGame.addMouseListener(this);
options.addMouseListener(this);
}
public void mouseClicked(MouseEvent e) {
if (e.getSource() == (startGame)) {
fireActionPerformed("startGame");
}
if (e.getSource() == (options)) {
fireActionPerformed("gameOptions");
}
}
public void mousePressed(MouseEvent e) {
}
public void mouseReleased(MouseEvent e) {
}
public void mouseEntered(MouseEvent e) {
}
public void mouseExited(MouseEvent e) {
}
public void addActionListener(ActionListener listener) {
listenerList.add(ActionListener.class, listener);
}
public void removeActionListener(ActionListener listener) {
listenerList.remove(ActionListener.class, listener);
}
protected void fireActionPerformed(String cmd) {
ActionListener[] listeners = listenerList.getListeners(ActionListener.class);
if (listeners != null && listeners.length > 0) {
ActionEvent evt = new ActionEvent(this, ActionEvent.ACTION_PERFORMED, cmd);
for (ActionListener listener : listeners) {
listener.actionPerformed(evt);
}
}
}
}
Menu Screen...
And when you click start...the game screen...
Now this is an EXAMPLE. Please try and take the time to understand what it going on in the code before you march ahead and implement it. I used by own images, you'll need to get your own..

There are several ways to stop your JPanel from "appearing" depending on exactly what you want to accomplish. One was it to to call setOpaque(false);. I'm not entirely sure how this affects custom painting, though.
Another posibility is
Container parent = getParent().remove(this);
parent.validate();
A third posibility is to add a flag in your class which is set when you click on a JLabel (or better yet a JButton -- see comments below). Then in your paintComponent() method you can check the flag and draw accordingly.
Note:
You are incorrectly using a JLabel and mouse events to respond to user input. Typically in a Swing application, we use JButtons and ActionListeners to accomplish what you are trying to do here. One advantage of this is that you only have to implement one method called onActionPerformed() and don't need to worry about adding all the mouse event handlers that you don't want to even respond to.