Sudoku Generator (Example for the OSGi Lab)
Sudoku Generator (Example for the OSGi Lab)
This is my first attempt to build a simple Java application using the OSGi framework.
Some time ago I wrote a Sudoku Generator program using BASH version 4. You can find the code on my blog at selmys.wordpress.com. I've chosen this same example to rewrite in Java/OSGi.
Yes, I know my code (and lack of documentation) is sloppy. That's because I tried to focus on trying to figure out what goes into each bundle. I'm sure I got many things wrong but on the positive side, the code works and actually generates a 9x9 Sudoku puzzle, albeit on the console in text mode. Perhaps in the future I'll produce a GUI output - or maybe someone can do it for me?
Design and Implementation
First, let me say that I followed Jordan's Voting System example, for both the code as well as the writeup on this wiki.
Define the Service
Create the bundle ca.on.senecac.scs.sudoku
Create SudokuGenerator.java
package ca.on.senecac.scs.sudoku;
/**
* Defines the interface to the Sudoku Generator OSGi-based
* application.
*
* @author John Selmys
*
*/
public interface SudokuGenerator {
void generate(int row, int col);
}Define the MANIFEST.MF for the service
Manifest-Version: 1.0
Bundle-ManifestVersion: 2
Bundle-Name: Sudoku
Bundle-SymbolicName: ca.on.senecac.scs.sudoku
Bundle-Version: 1.0.0.qualifier
Bundle-RequiredExecutionEnvironment: JavaSE-1.6
Export-Package: ca.on.senecac.scs.sudokuDefine the Service Provider
Create the bundle ca.on.senecac.scs.sudoku.provider
Create SudokuActivator.java
package ca.on.senecac.scs.sudoku.provider;
import org.osgi.framework.BundleActivator;
import org.osgi.framework.BundleContext;
import ca.on.senecac.scs.sudoku.SudokuGenerator;
import ca.on.senecac.scs.sudoku.provider.internals.*;
/**
* The Sudoku Generator provider bundle is registered here.
*
* @author John Selmys
*
*/
public class SudokuActivator implements BundleActivator {
private static BundleContext context;
static BundleContext getContext() {
return context;
}
public void start(BundleContext bundleContext) throws Exception {
SudokuActivator.context = bundleContext;
SudokuGenerator sg = new SimpleSudokuGenerator();
context.registerService(SudokuGenerator.class.getName(), sg, null);
System.out.println("Sudoku Generator Registered !");
}
public void stop(BundleContext context) throws Exception {
SudokuActivator.context = null;
System.out.println("Sudoku Generator Stopped !");
}
}Create SimpleSudokuGenerator.java
package ca.on.senecac.scs.sudoku.provider.internals;
import java.util.Random;
import ca.on.senecac.scs.sudoku.SudokuGenerator;
/**
* The code to generate a Sudoku grid is here. Note that the
* method "generate(int,int)" is recursive.
*
* @author John Selmys
*
*/
public class SimpleSudokuGenerator implements SudokuGenerator {
static Grid g = new Grid(9);
static int counter = 0;
/**
* The computation of a random valid (9x9) Sudoku puzzle
* starts here.
*/
public void generate(int row, int col) {
if(row > 8) {
puzzle();
System.out.println("All Done!");
g.display();
System.exit(0);
}
int[] a = {1,2,3,4,5,6,7,8,9};
get9(a);
for(int i=0;i<9;i++) {
int m = a[i];
counter++;
if(available(row,col,m)) {
g.setGrid(row, col, m);
if(col < 8) {
generate(row,col+1);
} else {
generate(row+1,0);
}
}
}
if(col > 0) {
col--;
} else {
col = 8;
row--;
}
g.setGrid(row, col, 0);
}
/**
* Make a 3x3 Sudoku puzzle and place into grid.
*
*/
static void puzzle() {
for(int r=0;r<7;r+=3) {
for(int c=0;c<7;c+=3) {
int x[] = {1,2,3,4,5,6,7,8,9};
get9(x);
for(int row=0;row<3;row++) {
for(int col=0;col<3;col++) {
int R = row+r;
int C = col+c;
int p = row * 3 + col + 1;
if(p==x[0] || p==x[1] || p==x[2] || p==x[3]) {
g.setGrid(R, C, 0);
}
}
}
}
}
}
/**
* Checks the grid to see if value 'm' can be placed at
* position (r,c)
*
*/
static boolean available(int r, int c, int m) {
for(int col=0;col<9;col++) {
if(g.getGrid(r, col) == m) return false;
}
for(int row=0;row<9;row++) {
if(g.getGrid(row, c) == m) return false;
}
r = r/3 * 3;
c = c/3 * 3;
for(int row=0;row<3;row++) {
for(int col=0;col<3;col++) {
int R = row + r;
int C = col + c;
if(g.getGrid(R, C) == m) return false;
}
}
return true;
}
/**
* Get an array containing integers [1..9] in random order.
*
*/
static void get9(int a[]) {
Random rand = new Random();
for(int i=8; i>0; i--) {
int r = rand.nextInt(i);
int t = a[i];
a[i] = a[r];
a[r] = t;
}
for(int k=0;k<9;k++)System.out.print(a[k]+" ");
System.out.println(" ");
}
}Create Grid.java
package ca.on.senecac.scs.sudoku.provider.internals;
/**
* The Sudoku Grid class contains the results of the Sudoku
* Generator.
*
* @author John Selmys
*
*/
public class Grid {
int[][] grid;
Grid(int side) {
grid = new int[side][side];
for (int i=0;i<9;i++)
for(int j=0;j<9;j++)
grid[i][j] = 0;
}
void display() {
for (int i=0;i<9;i++) {
for(int j=0;j<9;j++)
System.out.print(grid[i][j]+" ");
System.out.println();
}
}
void setGrid(int r, int c, int v) {
grid[r][c] = v;
}
int getGrid(int r, int c) {
return grid[r][c];
}
}Define the MANIFEST.MF
Manifest-Version: 1.0
Bundle-ManifestVersion: 2
Bundle-Name: Provider
Bundle-SymbolicName: ca.on.senecac.scs.sudoku.provider
Bundle-Version: 1.0.0.qualifier
Bundle-Activator: ca.on.senecac.scs.sudoku.provider.SudokuActivator
Bundle-ActivationPolicy: lazy
Bundle-RequiredExecutionEnvironment: JavaSE-1.6
Import-Package: ca.on.senecac.scs.sudoku,
org.osgi.framework;version="1.3.0"Define the Service Consumer
Create the bundle ca.on.senecac.scs.sudoku.client
Create ClientActivator.java
package ca.on.senecac.scs.sudoku.client;
import org.osgi.framework.BundleActivator;
import org.osgi.framework.BundleContext;
import org.osgi.framework.ServiceReference;
import ca.on.senecac.scs.sudoku.*;
/**
* Sudoku Generator client starts computing the Sudoku grid
* with a call to generate(0,0)
*
* @author John Selmys
*
*/
public class ClientActivator implements BundleActivator {
private static BundleContext context;
private SudokuGenerator sg;
static BundleContext getContext() {
return context;
}
public void start(BundleContext bundleContext) throws Exception {
ClientActivator.context = bundleContext;
ServiceReference reference = context
.getServiceReference(SudokuGenerator.class.getName());
if (reference != null) {
sg = (SudokuGenerator) context.getService(reference);
if (sg != null) {
sg.generate(0,0);
context.ungetService(reference);
} else
System.err.println("The Sudoku Generator cannot be used !!!");
} else
System.err.println("The Sudoku Generator cannot be found !!!");
}
public void stop(BundleContext bundleContext) throws Exception {
ClientActivator.context = null;
}
}Define the MANIFEST.MF
Manifest-Version: 1.0
Bundle-ManifestVersion: 2
Bundle-Name: Client
Bundle-SymbolicName: ca.on.senecac.scs.sudoku.client
Bundle-Version: 1.0.0.qualifier
Bundle-Activator: ca.on.senecac.scs.sudoku.client.ClientActivator
Bundle-ActivationPolicy: lazy
Bundle-RequiredExecutionEnvironment: JavaSE-1.6
Import-Package: ca.on.senecac.scs.sudoku,
org.osgi.framework;version="1.3.0"Configure the Sudoku Generator for running as an OSGi Implementation in the Eclipse Equinox container. Then run the application.
Note: In the console window you should see a valid Sudoku Puzzle printed out.