Cygwin : Unix simulator in Windows

This is my first post for unix shell scripting wherein I will try to provide tips,tricks and experiences that may be helpful in shell scripting.


If you are a Windows freak but your job forces you to learn shell scripting then maybe Cygwin software help you. Cygwin is a Unix-like environment and command-line interface for Microsoft Windows. This post is to introduce you about Cygwin and how to install Cygwin on Windows.

About Cygwin
Cygwin is basically a application developed for Windows environment that emulates Linux look and feel. Cygwin DLL provides most of the POSIX API functionality. Apart from these there are many popular application/tools which are developed for Windows that are available in Linux.

Cygwin is free and open source software which is maintained by volunteers and Red Hat is one of them. You may like to visit Cygwin website for further details.

Installing Cygwin
Cygwin installation is internet based i.e. throughout its installation internet connectivity is required mainly to download packages selected. However it does provide option to download packages first on local disk and install afterwords. Once downloaded you can install it on other machine if required.

Step 1: Go to link http://cygwin.com/setup.exe to download setup.exe for Cygwin.

Step 2: After downloading setup.exe run it. Following screen will appear.

Click Next.

Step 3) You will be asked to select one of three options for download. See image below for options. Since this is first time you are installing Cygwin, select first option i.e. Install from Internet.

Click Next.

Step 4) Here you will be prompted to select root directory. This is where files will be copied during installation. Also this will be '/' i.e. root directory as in Linux. In following example you will see "C:\cygwin" directory is entered. Thus "C:\cygwin" will be "/" for Cygwin Linux emulation.

Click Next.

Step 5) In next step you will be asked to select local package directory. As mentioned in image below this is where you installation file will be copied from internet. You can use this download later to select install Cygwin on other system without having internet connectivity.

Click Next.

Step 6) As shown in below image this option is to select internet connection. 

Click Next.

Step 7) In this you will have to select site from where Cygwin can be downloaded. These download site have supported Cygwin by hosting files to be downloaded. You may select any one of them.

Click Next. It will start connecting to the download site you have selected.

Step 8) Now you will have to select packages to be installed. As seen in image packages are categorized. In front of each package "Default" is written. Default means the minimum installation that will be required to run Cygwin. If you click Default it will rotate through different options such as Install,Uninstall and Reinstall package. In "Default" package selection some of packages may not be selected for installation. In that case use Install option to force installation of all packages in that category.

Further if you click "+" the selected category will expand and it will show the packages available under that category. For example in the following image I have expanded category "Editors" and selected "Install". i shows that all the editors available under this category will be installed. However I don't need all of them so I will select "vim" for Vi editor and rest I will uncheck by clicking checkbox under column name Bin.

Click Next to proceed for final setup.

After insallation is completed following screen will appear. Click Finish to complete setup.

After installation you will find icon to start Cygwin. Double click it to Start Cygwin application. Optionally you may start it by executing batch fille Cygwin.bat which is available in root directory  ( "C:\Cygwin" for this case ).

So finally you will see $ prompt on Windows. Now you can start experiencing Linux feel on Windows too !

Hope you like the post. Comments and suggestions are welcome.

Happy scripting !

Bodyguard Salman Khan's Dialogue and Russell's Paradox

The title of today's post may seem bit confusing as I am comparing a movie dialogue with the famous Russell's paradox. Well relax for now, this confusion will be cleared in a while.

Salman Khan in Bodyguard  Movie

Before going further, something about Salman Khan. If you are a Bollywood movie fan then you must be aware of him or probably one of his fan. He is one of the Indian Movie star who has given many hit movies and still continuing. 

To read more about Salman Khan read this IMDB page.

Bertrand Russell

Now about Bertrand Russell. He is one of the famous mathematician, logician of 20'th century. The famous Russell's paradox was stated by him whereby he showed the inconsistency in set theory. 

To read more about Bertrand Russell and his work read this Wikipedia article.

At this point, I think it is better to understand the Russell's Paradox through a well known example of barber's dilemma.

Barber's Dilemma:

Consider a small town where there is only one barber. The barber is supposed to shave all those men who can not shave themselves. Now question is "Who shaves the barber?". We can have two answers to this question but both leads to contradiction.

Answer 1)Barber shaves himself. This is a contradiction as barber can not shave those men who can shave themselves.

Answer 2)Barber doesn't shave himself. This is also a contradiction as barber is supposed to shave only those men who can not shave themselves.

You may like to read about it in detail in this wikipedia entry on Russell's Paradox.

Let us now come to the subject of today's post and find out how Bodyguard's Movie dialogue is another example of Russell's paradox. This Wednesday Salman Khan's movie "Bodyguard" has released. This movie has a dialogue which caught my attention and made me compare it with Russell's paradox. The whole dialogue ( in Hindi ) delivered by Bodyguard (the protagonist) is given below.

"मुझ पर एक एहसान करना के मुझपर कोई एहसान न करना."

It literally translates into English as "Do me a favor that don't do me any favor".

In my opinion this statement is contradictory. The protagonist is asking for a favor of not doing any favor to him. But by doing no favour we are doing a favor to him. Lets ask a question to ourselves. Are we doing a favor to the hero?

Answer 1) No. We are not doing any favor. This is contradiction as you are doing a favor by not doing a favor.

Answer 2) Yes. We are doing a favor. This is also contradiction as you are not asked to do any favor.

That's it. I hope I have proved my point. However your suggestions and comments in this regard are most welcome.

P.S. : I think this post is complete without video of the dialogue which inspired this post. Watch it below and all the best to Salman Khan for Bodyguard.

Minesweeper in Java Fx 2.0

Minesweeper v1.0 in JavaFx 2.0

This week I tried my hands at developing Minesweeper game in JavaFx 2.0 and the snapshot of version 1.0 is shown above. If OS installed on your laptop or PC is Microsoft Windows , then chances are that you might have played this game before. For those who don't know about this game here is a quick introduction to the rules.

As shown in snapshot below, the game consist of grid of identical squares. Some of these squares contains mines which of course are unknown to the player.

Minesweeper game when it starts.

The total number of mines is shown to the user. In above snapshot total number of mines is shown as "MINES REMAINING". Player has to identify mines location by flagging a square. A square is flagged by right clicking it.

But how do player know that particular square has hidden mine ? For this user has to click a square (sometimes randomly). Clicking a square reveals number of bombs in the adjacent square. This is explained in snapshots below.

In above case top left square was clicked. It reveals number of mines  in  adjacent  squares.

In above case squares are flagged for mines.

Player wins when he flags all the squares containing mines.By checking the count of mines in the adjacent squares player has to guess the presence of mine and flag it.

In above screenshot player has correctly flagged all squares containing  mine and thus he won .

However if player clicks a square containing mine then all mines get activated and explodes. In this case of course he has lost the game.

In above case used has clicked square containing mine and all mines exploded . Player  has lost the game .

If you want to read in detail about this game then head to this wikipedia article.

So much so far. Now lets come to the coding part.

The applications main class is Main defined in file Main.java. Nothing special about this class except that it is application entry point(public static void main) , defines stage and scene for application and finally creates instance for class Grid wherein we have coded our game.

package minesweeper;

import javafx.application.Application;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.paint.Color;
import javafx.stage.Stage;

public class Main extends Application {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        Application.launch(Main.class, args);
    }
    
    @Override
    public void start(Stage primaryStage) {
        primaryStage.setTitle("Minesweeper v1.0");
        
        
        primaryStage.setFullScreen(false);
        Group root = new Group();
        Scene scene = new Scene(root,Color.BLACK);

        root.getChildren().add(new Grid(9,9));
        primaryStage.setScene(scene);
        primaryStage.setVisible(true);
    }
}

In the whole project we have declared and used 4 classes. Main class we have just discussed above. Other 3 classes viz., Box ,Grid and Scoreboard are discussed below.

Box Class
Box class extends Parent class which is the base class for all nodes that have children in the scene graph. This class is used to draw a square in minesweeper.

Instance of  Box Class

As shown in figure above the Box class is nothing but a Rectangle drawn. However there is more in Box class. A square is minesweeper  has different states like flagged, uncover after user clicks it, showing count of number of mines(bombs) in adjacent squares and explode mine when user click a square having mine. All of these states are defined using attributes for Box class.

• Uncovered Box : When user clicks a Box(square in minesweeper) the box gets uncovered. We are showing box is uncovered by changing color of box. Further there are two possibilities when a Box is clicked. 1) Clicked box don't have mines in adjacent 8 squares. In this case no count is shown. 2) Clicked box have mine(s) in adjacent 8 squares. In this case number of bombs in adjacent square is shown.

Uncovered Box with no bomb in adjacent squares.

Uncovered Box with 2 bombs in adjacent squares.

           Attribute : boolean isCovered; 

• Flagged Box: When user right clicks a box the Box gets flagged. We are flagging a box by showing flag image on it. 

Flagged Box.

          Attribute: boolean isFlagged;

• Exploded Box: When user clicks a Box having mine , the mine explodes. We are showing this by displaying image of explosion on Box.

Exploded Box.

          Attribute: boolean isBomb;

There are some methods declared that sets the state of Box. These are explained below.

1. setBombBox() : This method is to add or remove bomb from Box. Attribute isBomb is set to true / false accordingly.
2. showBombCount(): This method is to display number of mines in adjacent square. Attribute used is bomb_count.
3. setCovered(): To uncover or cover a bomb.
4. explodeBomb(): To show exploded Box if Box is having attribute isBomb = true.
5. setFlagged(): Sets/Unsets the flag of the box. Attribute used is isFlagged.
6. setBoxColor(): Sets color of the box.
7. isBomb(),isCovered(),isFlagged() : As suggested in the method name itself it returns the boolean value of attribute.
8. getBombCount: Returns number of bombs in adjacent squares of the box.
9. resetBox(): This method resets all the attributes of Box and set the box to Covered state. This is used when to restart game.
10. setBoxPosition() : Sets the value of attributes posRow and posCol using the parameters passed. This value is used to get Box position in the Grid.
11. getBoxRow(),getBoxCol(): Returns posRow and posCol values respectively.

Thats all about Box class ! One thing should be remembered that Box class itself don't have game logic in it. It simply changes the state of the Box. It is the Grid class which dictates these changes and has game logic coded in it.

Grid Class

As the name suggests , Grid class is a Grid formed by Box objects. Like Box class, Grid class also extends Parent class.

Attributes of class are discussed in code snippet below. Please go through comments for the purpose of attributes.

int countColumn;//number of columns in the Grid.
    int countRow;//number of rows in the Grid.
    int countBomb;//number of Bombs(Mines) in the game.
    int countFlaggedBoxes=0;//number of boxes flagged by user.
    Box[][] boxGrid; //array to store objects of Box class.
    VBox vboxLayout; //layout to show children in vertical column
    ScoreBoard scoreBoard; //instance of inner class ScoreBoard.
    boolean isGameFinished = false; //whether game is finished 

Next is the constructor of Grid class.

public Grid(int cols,int rows)

The Grid constructor has arguments number of columns and rows. Accordingly it initializes boxGrid array with specified number of objects.This is of course done within for loops. While doing this we are also setting position of Box object within Grid. Also we are adding mouse events setOnMouseClicked,setOnMouseEntered,setOnMouseExited for each Box object within this loop.

Box objects on the same row are added in HBox layout and this HBox is then added in vboxLayout in the end. Thus we have a Grid of Boxes. You can imagine this.

Finally , we call setGamePuzzle() method to set game puzzle.

private void setGamePuzzle()

In this method we are first calculating total number of mines as 15% of total number of Boxes.

tempCountBomb = (int)((countColumn * countRow * 15.0)/100);

Then we place these many mines randomly in a Grid.

for (int i = 0; i < tempCountBomb; i++) {
            random_row=(int) (Math.random()*countRow);
            random_col=(int) (Math.random()*countColumn);
            boxGrid[random_row][random_col].setBombBox(true);
        }

There is a possibility that same pair of random row and column may generate twice and bomb will set twice for the same Box object. In such cases we are reducing count of bombs by 1.

After setting bombs for some Boxes we are initializing remaining Boxes which don't have bomb by number of bomb counts in the adjacent 8 squares. This is how game puzzle is set.

In the attributes list of Grid class you might have noticed ScoreBoard class. This is a inner class defined in class Grid. Purpose of scoreboard is to show total number of mines in the puzzle and guide user when he wins or losses games. It also have "RESTART GAME" button which resets the game.

ScoreBoard when game starts.

ScoreBoard when player wins game.

ScoreBoard when palyer losses game.

Instance of ScoreBoard is created in the Grid constructor and added in vboxLayout.

At this point game is ready and presented to the player. Now players interaction with application starts.

• When user clicks a Box which happens to be a Bomb Box then he loses the game and other hidden bombs also explodes. We also update scoreboard with message "Game Over".
• When user clicks a Box which is not a Bomb Box then we have to uncover that box and show user number of bombs present in the adjacent squares. If the clicked box don't have any bomb in adjacent square then we have to uncover all 8 adjacent squares and show number of bombs in the adjacent square of these squares. The process is recursive. This is handled in method showBombCounts() which is recursive. To get idea of this refer the image below. 

In above example player has clicked on a box which is marked in red color.

• When player right clicks a box we have flag tha box. If box is already flagged then we have to remove that flag.
• When user just hovers over the Covered Box with mouse cursor, we are changing color of box when cursor is on the Box. As soon as cursor exits box we are showing earlier color.

Here ends the description of the coding part. Hope you like the post ! 

Your suggestions are most welcome.

If you want to download jar file of the game it can be downloaded here. 

Javafx2.0 must be installed on your system to run this game. Get it from here.

Complete source code as a Netbeans Project is available here.
Get latest Netbeans IDE from here.

Introduction

package codesuffice.blogspot.com;
/**
 *
 * @author mangesh
 */
public class HelloWorld{
    HelloWorld(){
        System.out.println("Hello World !!");
        System.out.println("It is immensely pleasurable to write my first post for this blog. "
                + "The title 'Hello World !!' is an ode "
                + "to the first step in writing program for any language."
                + "Likewise I am writing my first post for this blog.");
    }


    public static void main(String[] args){
        HelloWorld helloWorld = new HelloWorld();
        helloWorld.Who_am_I('?');
        helloWorld.What_do_I_do('?');
        helloWorld.What_I_am_doing_here('?');
    }
    
    void Who_am_I(char question){
        System.out.println("I am a Software Engineer working in India.");
    }


    void What_do_I_do(char question){
        System.out.println("I do what a Software Engineer would do."
                + "Writing code and maintaining code.");
        //and if you don't know what a Software Engineer would do then 
        //probably you would not be here.
    }
    
    void What_I_am_doing_here(char question){
        System.out.println("Someday while sipping coffee "
                + "and relaxing after finding solution to a crude problem "
                + "a thought came to my mind. "
                + "What if I share such solutions with my fraternity of software minds?"
                + "I finished that cup of coffee with a plan to write blog "
                + "wherein I can share my experiences. "
                + "That's how I am here. "
                + "Beside this I like programming and "
                + "I would like to share some of my code which I have written.");
    }
}