Need some with a program that won't compile.

[Steve Vittoria]

Hi everyone! Hope I'm posting this in the right forum.

I'm trying to work with an example code of a Slide Puzzle game ( found here), and I get the following error when I try and compile it...

C:\My Projects\Slider\src\slider\SliderGUI.java:34: slider.SliderGUI.GraphicsPanel is not abstract and does not override abstract method mouseExited(java.awt.event.MouseEvent) in java.awt.event.MouseListener
class GraphicsPanel extends JPanel implements MouseListener {
Note: C:\My Projects\Slider\src\slider\Slider.java uses or overrides a deprecated API.
Note: Recompile with -Xlint eprecation for details.

Here is the code...

package slider;
 
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
 
class SliderGUI extends JPanel {
 
    // Instance variables.
    private GraphicsPanel _puzzleGraphics;
    private SliderLogic _puzzleModel = new SliderLogic();
 
    // Constructor
    public SliderGUI() {
        // Create a button and add a listener to it.
        JButton newGameButton = new JButton("New Game");
        newGameButton.addActionListener(new NewGameAction());
 
        // Create a control panel.
        JPanel controlPanel = new JPanel();
        controlPanel.setLayout(new FlowLayout());
        controlPanel.add(newGameButton);
 
        // Create a graphics panel.
        _puzzleGraphics = new GraphicsPanel();
 
        // Set the layout and add the components.
        this.setLayout(new BorderLayout());
        this.add(controlPanel, BorderLayout.NORTH);
        this.add(_puzzleGraphics, BorderLayout.CENTER);
    } // End of constructor.
 
    class GraphicsPanel extends JPanel implements MouseListener {
        private static final int ROWS = 3;
        private static final int COLS = 3;
        private static final int CELL_SIZE = 80;
        private Font _biggerFont;
 
        public GraphicsPanel() {
            _biggerFont = new Font("SansSerif", Font.BOLD, CELL_SIZE/2);
 
            this.setPreferredSize(new Dimension(CELL_SIZE * COLS, CELL_SIZE * ROWS));
            this.setBackground(Color.black);
            this.addMouseListener(this);
        } // End of constructor.
 
        public void paintComponent(Graphics g) {
            super.paintComponent(g);
 
            for (int r = 0; r < ROWS; r++) {
                for (int c = 0; c < COLS; c++) {
                    int x = c * CELL_SIZE;
                    int y = r * CELL_SIZE;
                    String text = _puzzleModel.getFace(r, c);
 
                    if (text != null){
                        g.setColor(Color.gray);
                        g.fillRect(x + 2, y + 2, CELL_SIZE - 4, CELL_SIZE - 4);
                        g.setColor(Color.black);
                        g.setFont(_biggerFont);
                        g.drawString(text, x + 20, y + (3 * CELL_SIZE) / 4);
                    }
                }
            }
        } // End of paintComponent.
 
        public void mousePressed(MouseEvent e) {
            int col = e.getX()/CELL_SIZE;
            int row = e.getY()/CELL_SIZE;
 
            if (!_puzzleModel.moveTile(row, col)) {
                // moveTile moves the tile if legal, else returns false.
                Toolkit.getDefaultToolkit().beep();
            }
 
            this.repaint();
        } // End of mousePressed.
    } // End of GraphicsPanel.
 
    public class NewGameAction implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            _puzzleModel.reset();
            _puzzleGraphics.repaint();
        } // End of actionPerformed.
    } // End of NewGameAction.
 
} // End of SliderGUI

I'm new to Java so I'm having a whale of a time trying to figure out what the compiler is trying to tell me. Any clues?

Thanks!
Steve

[Ernest Friedman-Hill]

The first error about not being abstract is trying to tell you that since your class SliderGUI.GraphicsPanel declares that it implements MouseListener, it must implement all the methods declared in the MouseListener interface; you've only implemented one. mousePressed(). The error message names another one, mouseExited(), but there are four more, I believe. You'll have to look it up in the Javadoc.

The second warning message about a deprecated API, you can get more specifics if you compile with the -Xlint switch to javac. A "deprecated API" is a class or method in the library that you shouldn't use anymore because a better alternative exists; it's still there only for backwards compatibility. Use -Xlint to find out what deprecated API you're using, and then go look at the Javadoc for that class or method -- it will tell you what to use instead.

[Marilyn de Queiroz]

I'm not having that problem. Are you copying/pasting the code? Are you putting the three classes each in their own file?

[Steve Vittoria]

Thanks for the replies guys.

Ok, so added -Xlint option and I don't get that much more information. Here's what I get with -Xlint enable...

Created dir: C:\My Projects\Slider\build\classes
Compiling 3 source files to C:\My Projects\Slider\build\classes
C:\My Projects\Slider\src\slider\SliderGUI.java:34: slider.SliderGUI.GraphicsPanel is not abstract and does not override abstract method mouseExited(java.awt.event.MouseEvent) in java.awt.event.MouseListener
class GraphicsPanel extends JPanel implements MouseListener {
C:\My Projects\Slider\src\slider\SliderGUI.java:34: warning: [serial] serializable class slider.SliderGUI.GraphicsPanel has no definition of serialVersionUID
class GraphicsPanel extends JPanel implements MouseListener {
C:\My Projects\Slider\src\slider\SliderGUI.java:8: warning: [serial] serializable class slider.SliderGUI has no definition of serialVersionUID
class SliderGUI extends JPanel {
1 error
2 warnings
BUILD FAILED (total time: 0 seconds)

I had a look at the Javadoc and I'm still confused as to what I have to do. According to the Javadoc, "the class that is interested in processing a mouse event either implements this interface (and all the methods it contains) or extends the abstract MouseAdapter class (overriding only the methods of interest)."

So I tried doing the following, but still it didn't work...

    class GraphicsPanel extends JPanel implements MouseListener {
        private static final int ROWS = 3;
        private static final int COLS = 3;
        private static final int CELL_SIZE = 80;
        private Font _biggerFont;
 
        public GraphicsPanel() {
            _biggerFont = new Font("SansSerif", Font.BOLD, CELL_SIZE/2);
 
            this.setPreferredSize(new Dimension(CELL_SIZE * COLS, CELL_SIZE * ROWS));
            this.setBackground(Color.black);
            this.addMouseListener(this);
        } // End of constructor.
 
        public void paintComponent(Graphics g) {
            super.paintComponent(g);
 
            for (int r = 0; r < ROWS; r++) {
                for (int c = 0; c < COLS; c++) {
                    int x = c * CELL_SIZE;
                    int y = r * CELL_SIZE;
                    String text = _puzzleModel.getFace(r, c);
 
                    if (text != null){
                        g.setColor(Color.gray);
                        g.fillRect(x + 2, y + 2, CELL_SIZE - 4, CELL_SIZE - 4);
                        g.setColor(Color.black);
                        g.setFont(_biggerFont);
                        g.drawString(text, x + 20, y + (3 * CELL_SIZE) / 4);
                    }
                }
            }
        } // End of paintComponent.
 
        public void mousePressed(MouseEvent e) {
            int col = e.getX()/CELL_SIZE;
            int row = e.getY()/CELL_SIZE;
 
            if (!_puzzleModel.moveTile(row, col)) {
                // moveTile moves the tile if legal, else returns false.
                Toolkit.getDefaultToolkit().beep();
            }
 
            this.repaint();
        } // End of mousePressed.
 
        public void mouseClicked(MouseEvent e) {
        } // End of mouseClicked.
 
        public void mouseReleased(MouseEvent e) {
        } // End of mouseReleased.
 
        public void mouseEntered(MouseEvent e) {
        } // End of mouseEntered.
 
        public void mouseExtited(MouseEvent e) {
        } // End of mouseExtited.
    } // End of GraphicsPanel.

I'm sure this is a quite simple problem, but I can't see the solution. Any tips?

[Ernest Friedman-Hill]

That's real close but...

public void mouseExtited(MouseEvent e) {

compilers are real picky about spelling!

[Steve Vittoria]

Thank you so much Ernest!