Transforming a program to an applet

Question

Hello a friend and i wanted to add a slider puzzle game to our website and for educational purposes ofc.We found a source code but its a program and not an applet.How can we convert it to an working applet? The program is

import javax.swing.JFrame;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
///////////////////////////////////////////// class SlidePuzzle
class SlidePuzzle {
    //============================================= method main
    public static void main(String[] args) {
        JFrame window = new JFrame("Slide Puzzle");
        window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        window.setContentPane(new SlidePuzzleGUI());
        window.pack();  // finalize layout
        window.show();  // make window visible
        window.setResizable(false);
    }//end main
}//endclass SlidePuzzle




/////////////////////////////////////////////////// class SlidePuzzleGUI
// This class contains all the parts of the GUI interface
class SlidePuzzleGUI extends JPanel {
    //=============================================== instance variables
    private GraphicsPanel    _puzzleGraphics;
    private SlidePuzzleModel _puzzleModel = new SlidePuzzleModel();
    //end instance variables


    //====================================================== constructor
    public SlidePuzzleGUI() {
        //--- Create a button.  Add a listener to it.
        JButton newGameButton = new JButton("New Game");
        newGameButton.addActionListener(new NewGameAction());

        //--- Create control panel
        JPanel controlPanel = new JPanel();
        controlPanel.setLayout(new FlowLayout());
        controlPanel.add(newGameButton);

        //--- Create 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 constructor


    //////////////////////////////////////////////// class GraphicsPanel
    // This is defined inside the outer class so that
    // it can use the outer class instance variables.
    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; // Pixels
        private Font _biggerFont;


        //================================================== constructor
        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);  // Listen own mouse events.
        }//end constructor


        //=======================================x method paintComponent
        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 paintComponent


        //======================================== listener mousePressed
        public void mousePressed(MouseEvent e) {
            //--- map x,y coordinates into a row and col.
            int col = e.getX()/CELL_SIZE;
            int row = e.getY()/CELL_SIZE;

            if (!_puzzleModel.moveTile(row, col)) {
                // moveTile moves tile if legal, else returns false.
                Toolkit.getDefaultToolkit().beep();
            }

            this.repaint();  // Show any updates to model.
        }//end mousePressed


        //========================================== ignore these events
        public void mouseClicked (MouseEvent e) {}
        public void mouseReleased(MouseEvent e) {}
        public void mouseEntered (MouseEvent e) {}
        public void mouseExited  (MouseEvent e) {}
    }//end class GraphicsPanel

    ////////////////////////////////////////// inner class NewGameAction
    public class NewGameAction implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            _puzzleModel.reset();
            _puzzleGraphics.repaint();
        }
    }//end inner class NewGameAction

}//end class SlidePuzzleGUI






class SlidePuzzleModel {
    private static final int ROWS = 3;
    private static final int COLS = 3;

    private Tile[][] _contents;  // All tiles.
    private Tile     _emptyTile; // The empty space.


    //================================================= constructor
    public SlidePuzzleModel() {
        _contents = new Tile[ROWS][COLS];
        reset();               // Initialize and shuffle tiles.
    }//end constructor


    //===================================================== getFace
    // Return the string to display at given row, col.
    String getFace(int row, int col) {
        return _contents[row][col].getFace();
    }//end getFace


    //======================================================= reset
    // Initialize and shuffle the tiles.
    public void reset() {
        for (int r=0; r<ROWS; r++) {
            for (int c=0; c<COLS; c++) {
                _contents[r][c] = new Tile(r, c, "" + (r*COLS+c+1));
            }
        }
        //--- Set last tile face to null to mark empty space
        _emptyTile = _contents[ROWS-1][COLS-1];
        _emptyTile.setFace(null);

        //-- Shuffle - Exchange each tile with random tile.
        for (int r=0; r<ROWS; r++) {
            for (int c=0; c<COLS; c++) {
                exchangeTiles(r, c, (int)(Math.random()*ROWS)
                                  , (int)(Math.random()*COLS));
            }
        }
    }//end reset


    //==================================================== moveTile
    // Move a tile to empty position beside it, if possible.
    // Return true if it was moved, false if not legal.
    public boolean moveTile(int r, int c) {
        //--- It's a legal move if the empty cell is next to it.
        return checkEmpty(r, c, -1, 0) || checkEmpty(r, c, 1, 0)
            || checkEmpty(r, c, 0, -1) || checkEmpty(r, c, 0, 1);
    }//end moveTile


    //================================================== checkEmpty
    // Check to see if there is an empty position beside tile.
    // Return true and exchange if possible, else return false.
    private boolean checkEmpty(int r, int c, int rdelta, int cdelta) {
        int rNeighbor = r + rdelta;
        int cNeighbor = c + cdelta;
        //--- Check to see if this neighbor is on board and is empty.
        if (isLegalRowCol(rNeighbor, cNeighbor) 
                  && _contents[rNeighbor][cNeighbor] == _emptyTile) {
            exchangeTiles(r, c, rNeighbor, cNeighbor);
            return true;
        }
        return false;
    }//end checkEmpty


    //=============================================== isLegalRowCol
    // Check for legal row, col
    public boolean isLegalRowCol(int r, int c) {
        return r>=0 && r<ROWS && c>=0 && c<COLS;
    }//end isLegalRowCol


    //=============================================== exchangeTiles
    // Exchange two tiles.
    private void exchangeTiles(int r1, int c1, int r2, int c2) {
        Tile temp = _contents[r1][c1];
        _contents[r1][c1] = _contents[r2][c2];
        _contents[r2][c2] = temp;
    }//end exchangeTiles


    //=================================================== isGameOver
    public boolean isGameOver() {
        for (int r=0; r<ROWS; r++) {
            for (int c=0; c<ROWS; c++) {
                Tile trc = _contents[r][c];
                return trc.isInFinalPosition(r, c);
            }
        }

        //--- Falling thru loop means nothing out of place.
        return true;
    }//end isGameOver
}//end class SlidePuzzleModel



////////////////////////////////////////////////////////// class Tile
// Represents the individual "tiles" that slide in puzzle.
class Tile {
    //============================================ instance variables
    private int _row;     // row of final position
    private int _col;     // col of final position
    private String _face;  // string to display 
    //end instance variables


    //==================================================== constructor
    public Tile(int row, int col, String face) {
        _row = row;
        _col = col;
        _face = face;
    }//end constructor


    //======================================================== setFace
    public void setFace(String newFace) {
        _face = newFace;
    }//end getFace


    //======================================================== getFace
    public String getFace() {
        return _face;
    }//end getFace


    //=============================================== isInFinalPosition
    public boolean isInFinalPosition(int r, int c) {
        return r==_row && c==_col;
    }//end isInFinalPosition
}//end class Tile

I tried to edit it like an applet but it does not get initialited

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
import java.io.*;
import java.awt.*;
import java.util.*;
import java.applet.*;
import javax.swing.*;
import java.awt.event.*;
import javax.swing.event.*;
/////////////////////////////////;////////////////// class SlidePuzzleGUI
// This class contains all the parts of the GUI interface
class SlidePuzzleGUI  extends JApplet {
    //=============================================== instance variables
    private GraphicsPanel    _puzzleGraphics;
    private SlidePuzzleModel _puzzleModel = new SlidePuzzleModel();
    //end instance variables
 JPanel controlPanel = new JPanel();

    //====================================================== constructor
    public SlidePuzzleGUI() {
        //--- Create a button.  Add a listener to it.
        JButton newGameButton = new JButton("New Game");
        newGameButton.addActionListener(new NewGameAction());

        //--- Create control panel

        controlPanel.setLayout(new FlowLayout());
        controlPanel.add(newGameButton);

        //--- Create 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 constructor


    //////////////////////////////////////////////// class GraphicsPanel
    // This is defined inside the outer class so that
    // it can use the outer class instance variables.
    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; // Pixels
        private Font _biggerFont;


        //================================================== constructor
        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);  // Listen own mouse events.
        }//end constructor


        //=======================================x method paintComponent
        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 paintComponent


        //======================================== listener mousePressed
        public void mousePressed(MouseEvent e) {
            //--- map x,y coordinates into a row and col.
            int col = e.getX()/CELL_SIZE;
            int row = e.getY()/CELL_SIZE;

            if (!_puzzleModel.moveTile(row, col)) {
                // moveTile moves tile if legal, else returns false.
                Toolkit.getDefaultToolkit().beep();
            }

            this.repaint();  // Show any updates to model.
        }//end mousePressed


        //========================================== ignore these events
        public void mouseClicked (MouseEvent e) {}
        public void mouseReleased(MouseEvent e) {}
        public void mouseEntered (MouseEvent e) {}
        public void mouseExited  (MouseEvent e) {}
    }//end class GraphicsPanel

    ////////////////////////////////////////// inner class NewGameAction
    public class NewGameAction implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            _puzzleModel.reset();
            _puzzleGraphics.repaint();
        }
    }//end inner class NewGameAction
 public void init() { System.out.println("Applet initializing");
SlidePuzzleGUI d = new SlidePuzzleGUI();
controlPanel.add(d);
}
public void start() {
System.out.println("Applet starting");
}
public void stop() {
System.out.println("Applet stopping");
}
public void destroy() {
System.out.println("Applet destroyed");
}
public static void main(String args[]){
JFrame frame = new JFrame("Code Converter");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
SlidePuzzleGUI a = new SlidePuzzleGUI();
a.init();

frame.setContentPane(new SlidePuzzleGUI());
frame.pack();
frame.show();

}//end class SlidePuzzleGUI
}

What am i doing wrong?What do i need to do to transform it correctly?

Hovercraft Full Of Eels · Accepted Answer · 2012-05-19T15:23:57.243

I fear that there's too much involved to give a simple summary here other than for you to read the Oracle Swing Applet Tutorials on how to create GUI's and JApplets and then re-write or modify this code to become an applet.

As to what you're doing wrong

do you have any errors or exceptions?
what is your code currently doing?
Do you have any debug code present that helps you check the state of your program as it's running?
you don't appear to be adding anything to the applet's contentPane yet and appear to be trying to call the init() method directly. This suggests that you haven't looked at the tutorials yet -- you should do this first before coming here.

I can say that you'll need a class that extends JApplet, that you won't need or have a main method, that you'll want to gear your GUI towards creating a JPanel, that you'll often build your GUI in your gui class's constructor and then add it to the JApplet's contentPane in the applet's init() method, but the details are too important to ignore. Again read the tutorials, and then come on back if you get stuck and have a specific answerable question.

Note that in general you'll want to avoid using "borrowed" code, especially early in the game. Better to study the code, and then write your own program from scratch using the ideas you've obtained from the downloaded code.

hmm i tried it but the classes we get in uni and tutorials didnt help much.I am gonna study the code and try to write an app from scratch.If i got an issue i am gonna write a new post..Thanks for the info. — Amethyst0z, May 19 '12 at 15:27

score 1 · Answer 2 · edited May 23 '17 at 12:04

wanted to add a slider puzzle game to our website..

Don't do any conversion of the code. Instead, add the classes to a Jar, write a JNLP file to launch it (similar to the applet HTML), and provide the user a button to Play Slider Puzzle

When(/if) the user decides to click the link, the app. will be downloaded and launched direct from the site using Java Web Start.

This is an approach that will provide a better user experience, with fewer deployment problems.

Transforming a program to an applet

2 Answers2