knowledge For All: 2012

Validate the Prime Number in java

this is the method to identify the prime numbers

import java.util.*;

public class prime
{
int n;
    public static void main(String args[])
    {
        Scanner m=new Scanner(System.in);
        System.out.println("Enter your number");
        int P=m.nextInt();
        prime input=new prime();
        input.check(P);
    }

    void check(int P)
        {
            for(int i=2;i<P;i++)
            {
                if(P%i!=0)
                    {
                        n=0;
                    }
                else if(P%i==0)
                    {
                        n=1;break;
                    }
            }
                if(n==0)
                {
                    System.out.println("prime");
                }
                else if(n==1)
                {
                    System.out.println("not prime");
                }
        }
}

Validate the Prime Number in java

this is the method to identify the prime numbers

Let's learn to connect the php with MySQL Database to store and retrieve data
<?php
$host='localhost';
$user='root';
$pass='';
$database_name='user';
?>

<?php
    require_once 'config/config.php';
    $connect = mysql_connect($host,$user,$pass) or die("Connection to server failed");
    mysql_select_db($database_name,$connect) or die("Connection to database failed");

    $name = $_POST['name'];
    $phone_no = $_POST['phone'];
    $email = $_POST['email_addr'];

    $result=mysql_query("INSERT INTO userdetails(Name,PhoneNo,Email) VALUES ('$name',$phone_no,'$email')",$connect);
    echo $result;
    if($result){
        echo "Successfully inserted";

    }
    mysql_close($connect);
?>

#main
{
    background-color:#00FF00;
    width:300;
    height:100;
    position:absolute;
    margin-left:400;
    margin-top:200;
    padding-left:10;
    padding-top:10;
}
#mainbody
{
    background-color:#00FF00;
    width:350;
    height:250;
    position:absolute;
    margin-left:300;
    margin-top:200;
    padding-left:10;
    padding-top:10;
}


<html>
    <head>
        <title>HTML Form</title>
        <link rel="stylesheet" type="text/css" href="style.css" >
        <script src="validation.js" type="text/javascript" xml:space="preserve"></script>
    </head>
    <body bgcolor="#9999CC">
    <div id="mainbody">
        <form name="details" action="insert.php" onsubmit="return validateFormOnSubmit(details)" method="POST" >
            <p>
            Enter your name:
            <br />
            <input type="text" size=50 name="name" />
            <p>
            Enter your phone:
            <br />
            <input type="text" size=50 name="phone" />
            <p>
            Enter your email address:
            <br />
            <input type="text" size=50 name="email_addr" />
            <p>
            <input type=submit value="submit" />
            <input type=reset value="clear" />
        </form>
    </div>
    </body>
</html>

PHP Connection With MySql DataBase

import java.util.*;
//our scanner class we are going to derive from this library
import java.io.*;
// it's a library it's have some input output functions and methods in this program we are going to read and write files so we need this library

public class encryption
{
    static String plaintxt,ciphertxt,cryptxt;
    static int key,selct;
    char k;
    char Mono[];

//read text from file
    private void readfile(String filename) throws IOException
//here we put Io Exception because file may not be in your folder so programe may show error or corrupt to prevent this error in Runtime we use exception
        {
            try
            {
//if try method cannot perform it will call catch method
                File rFile=new File(filename);
//An abstract representation of file and directory pathnames so that instance rFile indicate a full path of given file filname
                Scanner sc=new Scanner(rFile);
//Read the file in given path name rFile
                cryptxt="";
//we wanr to assign empty otherwise it will take null value in results
                while(sc.hasNext())
//hasNext( ) is a special method in scanner class to verify next line have or not
                    {
                        cryptxt+=sc.nextLine()+" \n";
// method in scanner class to read lines and return value
                        cryptxt=cryptxt.toLowerCase();
                      }
            }

            catch(FileNotFoundException e)
            {
//if try method can not perform this method will do whatever in this catch method we say
                System.out.println("Error|"+ filename+"not found");
//so here if file not in folder then programe will show that particular filr not found
            }
        }

    public void writefile(String filename) throws IOException
    //write file in given name
        {
            PrintWriter fout=new PrintWriter(filename);
// Creates a new PrintWriter, without automatic line flushing, with the specified file name
            fout.append(ciphertxt);
//Appends the specified character sequence to this writer.
            fout.close();
// Closes the stream and releases any system resources associated with it.
            System.out.println("your New Encrypted file successfully created or Encrypted Text Added");
        }

    public static void main(String args[]) throws IOException
    {
        Scanner n=new Scanner(System.in);
//to take the input from outside
        encryption e1=new encryption();
//creating new instance of our Encryption class
        System.out.println("What type of cipher model you want(press 1 or 2) \n 1. ceaser cipher \n 2.Monoalphabetic");
        selct=n.nextInt();
//assign the input integer to selct variable of n that's a instance of encryption class
        if(selct==1)
    {
//In this stage we are going to select what type of action we are going to do it's mean encryption or decryption
        System.out.println("Enter Your Method You Want(press 1 or 2) \n 1.Encryption \n 2.Decryption");
        selct=n.nextInt();

        if(selct==1)
          {
//method to Encryption
            System.out.println("Welcome to Encryption Method \n Enter Your Key Value");
            key=n.nextInt();
//assign the value of the key to variable key because of it's global variable this value will take global value to key variable

            System.out.println("Please Enter Your File Name That You Want To Encrypt");
            String Fnme=n.next();
//get the file name that we wish to encrypt
            e1.readfile(Fnme);
//sent the name of the file we want to read to readfile method

            System.out.println("Your Text Read From Your File \n");
            System.out.println(cryptxt);
// to show text that read from file in console before encrypt

            e1.encrypt();
//call the encrypt method to encrypt our text that were read from our file

            System.out.println("Please Enter File Name That Want to save new Encrypted file");
            String Nnme=n.next();
// get the file name we wish to save our encrypted file
            e1.writefile(Nnme);
//sent the file name to writefile method
        }
        else if(selct==2)
//method to Decryption
        {

//Here we have two chances 1st one is we know the key of the encrypted text 2nd one is we don't know the encrypted text key value
            System.out.println("Do you know the key value?? (press 1 or 2) \n 1. i know the key \n 2. i Don't know the key value" );
            int crypt=n.nextInt();
            if(crypt==1)
//when key know
            {
                System.out.println("Welcome to Deccryption method \n enter your key value");
                key=n.nextInt();
// get the value of the encrypted text key

                System.out.println("\n please enter your file name that you want to Decrypt");
                String Fnme=n.next();
//get the file name that we wish to decrypt

                e1.readfile(Fnme);
//sent the name of the file we want to read to readfile method

                System.out.println("Your Text Read From Your File \n");
                System.out.println(cryptxt);
// to show text that read from file in console before decrypt

                e1.Decrypt();
//call the Decrypt method to Decrypt our text that were read from our file
            }
            else if(crypt==2)
//when key don't know
            {
//key value but we don't know however key is going to be within 26 so we can check all numbers which is correct
                System.out.println("\n please enter your file name that you want to Decrypt");
                String Fnme=n.next();
//get the file name that we wish to decrypt

                System.out.println("Your Text Read From Your File \n");
                e1.readfile(Fnme);
//sent the name of the file we want to read to readfile method
                System.out.println(cryptxt);
// to show text that read from file in console before decrypt

                e1.cryptAnalys();
//call the cryptAnalys method to check the key value and to find original message
            }
            else
            {
                System.out.println("please press 1 or 2");
            }

            System.out.println("\n please enter file name that want to save new Decrypted file");
            String Nnme=n.next();
// get the file name we wish to save our decrypted file
            e1.writefile(Nnme);
//sent the file name to writefile method
        }
        else
        {

            System.out.println("please press 1 or 2");
        }
    }
}

    public void encrypt()
    {
        ciphertxt="";
//if not assign empty it's will print null value in file

        int l=cryptxt.length()-1;
        int as;
        String cyp="";

        for(int i=0; i<l;i++)
        {
//here we are going to get each and every character in cryptxt then get the ASCII value of that character then if it is a English character then encrypt using key then joint them then we get encrypted text
            k=cryptxt.charAt(i);
            as=(int)k;
//get the ASCII value of each and every character in cryptxt and assign it to variable as
            if(as>96&&as<124)
//checking is it corrector or symbol
            {
//if it is a English lowercase character then we are going to add key value with the ascii value of the every character but we want to consider result value want to be within the boundary of the English lowercase character ascii values so here we are doing some mechanism to keep it
                as=((as-97+key)%26)+97;
//here first we we eliminate the low index characters through subtract 97so now a's ASCII value is going to be 0 then we add key value but after that we take mod 26 because some times if char is z then value is going to be 25 then if we add key it's going to out of border so through take mod 26 we bring it within our boundary and it's not going to create any complexity within the characters because if key is 2 then a is going to be 2 and z is going to be 1 so no complexity

                ciphertxt=ciphertxt+(char)as;
//joint every encrypted characters to ciphertxt
            }
            else
            {
// if it is not English character then joint it to ciphertxt without any change
                ciphertxt=ciphertxt+(char)as;
            }
          }
        System.out.println("\n Your Text That Encrypted \n");
        System.out.println(ciphertxt);
//show in encrypted text in console
//another important think is we already assign ciphertxt as a global variable so if we assign ciphertxt value here it will be take as a global value to ciphertxt so wherever you call the ciphertxt after this step it will take this ciphertxt value to that one
    }

    public void Decrypt()
    {
        ciphertxt="";
//if not assign empty it's will print null value in file
        int l=cryptxt.length()-1;
        int as;
        String cyp="";

        for(int i=0; i<l;i++)
        {
            k=cryptxt.charAt(i);
            as=(int)k;
            if(as>96&&as<124)
//checking is it corrector or symbol
            {
                as=(as-97-key);
                if(as<0) as=as+26;
//here we are using different mechanism when we encrypt we subtract 97 and add key then take mod then add 97 but here just subtract 97 and key then check whether it's less then 0 or not if it is less then 0 add 26 because we know that char's are take that index because of out of range 26 so here we just add 26 it will take it's original index so then add 97 now we get original ASCII values of characters
                as=as+97;

                ciphertxt=ciphertxt+(char)as;
            }
            else
            {
                ciphertxt=ciphertxt+(char)as;
//add directly because it's nor corrector
            }

        }
        System.out.println("\n Your Yext That Decrypted \n");
        System.out.println(ciphertxt);
    }

    public void cryptAnalys()
    {
        Scanner m=new Scanner(System.in);
        for(int i=0;i<27;i++)
        {
            key=i;

            Decrypt();//call the decrypt method to one by one key values until result is satisfy
            System.out.println("Are you Satisfiy in this Decrypted Message?? \n 1.yes \n 2.No");
            int agree=m.nextInt();
            if(agree==1) break;//if result is satisfied then stop the loop
        }
    }

Encryption and Decryption

Bubble Sort method in java

this is the program to sort the given numbers in a accenting or decanting order

import java.util.*;

public class sorting
{
    int table[]=new int[5];
    public static void main(String arg[])
    {
        sorting m=new sorting();
        m.readArray();
        m.bubbleSort();
        m.print();
    }
        void bubbleSort()
        {
            for(int i=1;i<=4;i++)
            {
                for(int j=0;j<=(4-i);j++)
                {
                    if(table[j]>table[j+1])
                    swap(j,j+1);
                }
            }
        }

        void print()
        {
                System.out.print("sorted list of your numbers:");
            for(int i=0;i<=4;i++)
                {
                System.out.print(" "+table[i]);
                }
        }

        void readArray()
        {
            for(int i=0;i<=4;i++)
            {
                Scanner n=new Scanner(System.in);
                System.out.println("enter your number    "+(i+1));
                table[i]=n.nextInt();
            }
        }

        void swap(int x,int y)
        {
            int m=table[x];
            table[x]=table[y];
            table[y]= m;
        }
}

Bubble Sort method in java

this is the program to sort the given numbers in a accenting or decanting order

GCD (Greater common Divider ) in Java

this programe to find the greatest common divider when we enter two integer numbers

import java.util.*;
public class gcd
{
    public static void main(String arg[])
    {
    Scanner input = new Scanner(System.in);
        System.out.println("Enter your number 1");
        int n1 = input.nextInt();
        System.out.println("Enter your number 2");
        int n2 = input.nextInt();
    gcd m=new gcd();
    m.check(n1,n2);
    }

    void check(int n1,int n2)
    {
        for(int i=2;i<n1;i++)
        {
            if(n1%i==0&& n2%i==0)
            {
            System.out.println("GCD="+i);break;
            }
        }
    }
}

GCD (Greater common Divider ) in Java

this programe to find the greatest common divider when we enter two integer numbers

import java.io.IOException;

class Link {
  private int data;
  public Link next;

  public Link(int d) {
    data = d;
  }

  public int getKey() {
    return data;
  }

  public void displayLink() {
    System.out.print(data + " ");
  }
}

class SortedList {
  private Link first;
  public SortedList() {
    first = null;
  }

  public void insert(Link theLink){
    int key = theLink.getKey();
    Link previous = null; // start at first
    Link current = first;
    // until end of list,
        //or current bigger than key,
    while (current != null && key > current.getKey()) { 
      previous = current;
      current = current.next; // go to next item
    }
    if (previous == null) // if beginning of list,
      first = theLink; 
    else
      // not at beginning,
      previous.next = theLink; 
    theLink.next = current; 
  }

  public void delete(int key){ 
    Link previous = null; 
    Link current = first;

    while (current != null && key != current.getKey()) { 
      previous = current;
      current = current.next; 
    }
    // disconnect link
    if (previous == null) //   if beginning of list delete first link
      first = first.next;       
    else
      //   not at beginning
      previous.next = current.next; //delete current link
  }

  public Link find(int key) {
    Link current = first; 
    while (current != null && current.getKey() <= key) { // or key too small,
      if (current.getKey() == key) // found, return link
        return current;  
      current = current.next; // go to next item
    }
    return null; // cannot find it
  }

  public void displayList() {
    System.out.print("List: ");
    Link current = first;
    while (current != null){
      current.displayLink(); 
      current = current.next;
    }
    System.out.println("");
  }
}

public class HashChain {
  private SortedList[] hashArray; 

  private int arraySize;

  public HashChain(int size) {
    arraySize = size;
    hashArray = new SortedList[arraySize];
    for (int i = 0; i < arraySize; i++)
      hashArray[i] = new SortedList(); 
  }

  public void displayTable() {
    for (int j = 0; j < arraySize; j++) {
      System.out.print(j + ". "); 
      hashArray[j].displayList(); 
    }
  }

  public int hashFunc(int key) {
    return key % arraySize;
  }

  public void insert(Link theLink) {
    int key = theLink.getKey();
    int hashVal = hashFunc(key); 
    hashArray[hashVal].insert(theLink); 
  }

  public void delete(int key) {
    int hashVal = hashFunc(key); // hash the key
    hashArray[hashVal].delete(key); 
  }

  public Link find(int key) {
    int hashVal = hashFunc(key); // hash the key
    Link theLink = hashArray[hashVal].find(key); // get link
    return theLink;
  }

  public static void main(String[] args) throws IOException {
    int aKey;
    Link dataItem;
    int size, initSize, keysPerCell = 100;
    size = 20;
    initSize = 10;
    HashChain hashTable = new HashChain(size);

    for (int i = 0; i < initSize; i++){
      aKey = (int) (java.lang.Math.random() * keysPerCell * size);
      dataItem = new Link(aKey);
      hashTable.insert(dataItem);
    }
    hashTable.displayTable();
    aKey = 100;
    dataItem = new Link(aKey);
    hashTable.insert(dataItem);
    aKey = 100;
    hashTable.delete(aKey);

    aKey = 50;
    dataItem = hashTable.find(aKey);
    if (dataItem != null)
      System.out.println("Found " + aKey);
    else
      System.out.println("Could not find " + aKey);
  }

}

OUTPUT

0. List:
1. List:
2. List:
3. List: 1483
4. List: 204
5. List: 445 605
6. List: 1686
7. List:
8. List: 1748
9. List: 229
10. List:
11. List:
12. List:
13. List:
14. List:
15. List: 635
16. List:
17. List:
18. List: 1218
19. List: 379

Hash table with separate chaining

import java.io.IOException;

class Link {
  private int data;
  public Link next;

  public Link(int d) {
    data = d;
  }

  public int getKey() {
    return data;
  }

  public void displayLink() {
    System.out.print(data + " ");
  }
}

class SortedList {
  private Link first;
  public SortedList() {
    first = null;
  }

  public void insert(Link theLink){
    int key = theLink.getKey();
    Link previous = null; // start at first
    Link current = first;
    // until end of list,
        //or current bigger than key,
    while (current != null && key > current.getKey()) { 
      previous = current;
      current = current.next; // go to next item
    }
    if (previous == null) // if beginning of list,
      first = theLink; 
    else
      // not at beginning,
      previous.next = theLink; 
    theLink.next = current; 
  }

  public void delete(int key){ 
    Link previous = null; 
    Link current = first;

    while (current != null && key != current.getKey()) { 
      previous = current;
      current = current.next; 
    }
    // disconnect link
    if (previous == null) //   if beginning of list delete first link
      first = first.next;       
    else
      //   not at beginning
      previous.next = current.next; //delete current link
  }

  public Link find(int key) {
    Link current = first; 
    while (current != null && current.getKey() <= key) { // or key too small,
      if (current.getKey() == key) // found, return link
        return current;  
      current = current.next; // go to next item
    }
    return null; // cannot find it
  }

  public void displayList() {
    System.out.print("List: ");
    Link current = first;
    while (current != null){
      current.displayLink(); 
      current = current.next;
    }
    System.out.println("");
  }
}

public class HashChain {
  private SortedList[] hashArray; 

  private int arraySize;

  public HashChain(int size) {
    arraySize = size;
    hashArray = new SortedList[arraySize];
    for (int i = 0; i < arraySize; i++)
      hashArray[i] = new SortedList(); 
  }

  public void displayTable() {
    for (int j = 0; j < arraySize; j++) {
      System.out.print(j + ". "); 
      hashArray[j].displayList(); 
    }
  }

  public int hashFunc(int key) {
    return key % arraySize;
  }

  public void insert(Link theLink) {
    int key = theLink.getKey();
    int hashVal = hashFunc(key); 
    hashArray[hashVal].insert(theLink); 
  }

  public void delete(int key) {
    int hashVal = hashFunc(key); // hash the key
    hashArray[hashVal].delete(key); 
  }

  public Link find(int key) {
    int hashVal = hashFunc(key); // hash the key
    Link theLink = hashArray[hashVal].find(key); // get link
    return theLink;
  }

  public static void main(String[] args) throws IOException {
    int aKey;
    Link dataItem;
    int size, initSize, keysPerCell = 100;
    size = 20;
    initSize = 10;
    HashChain hashTable = new HashChain(size);

    for (int i = 0; i < initSize; i++){
      aKey = (int) (java.lang.Math.random() * keysPerCell * size);
      dataItem = new Link(aKey);
      hashTable.insert(dataItem);
    }
    hashTable.displayTable();
    aKey = 100;
    dataItem = new Link(aKey);
    hashTable.insert(dataItem);
    aKey = 100;
    hashTable.delete(aKey);

    aKey = 50;
    dataItem = hashTable.find(aKey);
    if (dataItem != null)
      System.out.println("Found " + aKey);
    else
      System.out.println("Could not find " + aKey);
  }

}

OUTPUT

0. List:
1. List:
2. List:
3. List: 1483
4. List: 204
5. List: 445 605
6. List: 1686
7. List:
8. List: 1748
9. List: 229
10. List:
11. List:
12. List:
13. List:
14. List:
15. List: 635
16. List:
17. List:
18. List: 1218
19. List: 379

Hash table drill program

import java.util.Random;
import java.io.*;
import java.util.Scanner;

public class HashDrill
{ // Selection the hash function for int hash()
   static private int   option = 0;

   static private boolean[] displaced;

   // Seeded in main, used in fillTable
   static Random generator = new Random();

   static Scanner console = new Scanner(System.in);

// Hash function, based on the selection option
   private static int hash ( int value, int size )
   { int d1 = Math.abs(value),
          d0 = d1 % 10;
      int key = d1 % size;   // Used for single-digit value

      // More than one digit; isolate d1 and compute.
      if ( d1 != d0 )
      { while ( d1 > 9 )
            d1 /= 10;
         if ( option == 0 )
            key = (d1*10 + d0) % size;
         else
            key = (d1 * d0) % size;
      }
      return key;
   }

   // Fill table[], val[] and key[]
   private static void fillTable ( int[] table, int[] val, int[] key )
   { int j, k,
          size = table.length;

      // Initialize the table to empty (-1 throughout)
      for ( j = 0; j < size; j++ )
         table[j] = -1;

      // Generate the values, then place them into the table
      for ( j = 0; j < val.length; j++ )
      { k = generator.nextInt(4) + 1;
         val[j] = generator.nextInt((int)Math.pow(10,k));
         k = hash(val[j], size);
         key[j] = k;

         // Linear probe for an available cell
         while ( table[k] != -1 )
            k = (k+1) % size;
         // Position the value into the table
         table[k] = val[j];
         displaced[k] = k != hash(val[j], size);
      }
   }

   // Display table[], val[] and key[]
   private static void showTable ( int[] table, int[] val, int[] key )
   { int j;

      System.out.println ("\nd1 is the leading digit, d0 the trailing." +
         "\nHash function: " +
         ( option == 0 ? "(d1*10 + d0) % " : "(d1 * d0) % " ) +
         table.length );

      System.out.println ("\nindex    value key");
      for ( j = 0; j < val.length; j++ )
         System.out.printf ("%5d %8d %4d\n", j, val[j], key[j]);

      System.out.print ("\nPress enter to see the hash table.");
      console.nextLine();

      System.out.println ("\nindex    table");
      for ( j = 0; j < table.length; j++ )
      { System.out.printf ("%5d %8d", j, table[j]);
         if (displaced[j]) System.out.print(" *");
         System.out.println();
      }
   }

   public static void main ( String[] args )
   { long   seed = generator.nextLong();
      int    size = -1;
      int[] table;
      int[] val = new int[10];
      int[] key = new int[10];
      int    j, k;

      System.out.print ("Size: ");
      if ( args.length > 0 )
      { try
         { size = Integer.parseInt(args[0].trim()); }
         catch (Exception e)
         { System.out.println(e); System.exit(-1); }
         System.out.println(size);
      }
      else
      { size = console.nextInt(); console.nextLine(); }
      table = new int[size];
      displaced = new boolean[size];

      if ( args.length > 1 )
      { try
         { option = Integer.parseInt(args[1].trim()); }
         catch (Exception e)
         { System.out.println(e); System.exit(-1); }
      }

      if ( args.length > 2 )
      { try
         { seed = Long.parseLong(args[2].trim()); }
         catch (Exception e)
         { System.out.println(e); System.exit(-1); }
         System.out.println("Setting seed to " + seed);
      }
      generator.setSeed(seed);

      fillTable(table, val, key);

      showTable(table, val, key);
      System.out.print ("\nPress enter to exit.");
      console.nextLine();
   }
}

OUTPUT

Size: 10

d1 is the leading digit, d0 the trailing.
Hash function: (d1*10 + d0) % 10

index    value key
    0      501    1
    1      997    7
    2     3252    2
    3      624    4
    4      939    9
    5       46    6
    6      923    3
    7        8    8
    8       99    9
    9        8    8

Press enter to see the hash table.

index    table
    0       99 *
    1      501
    2     3252
    3      923
    4      624
    5        8 *
    6       46
    7      997
    8        8
    9      939

Hash table drill program

The n-Queens Problem

import java.util.*; //to import Scanner class for take the value from user of the chess board

public class quen{

int[] x=new int[16]; //allocate a location for array storage

public void Nquens(int r, int n){

for(int c=0;c<n;c++){

if (canPlace(r,c)){

x[r] =c;

if(r==n-1){ //it's say successfully filled

print(x,n);

board(x,n);

break;

}

else Nquens(r+1,n); //call or move 1st one queen to up box

}

boolean canPlace(int r,int t){ // to check can place or not

for(int i=0;i<r;i++){

if (x[i]==t||Math.abs(i-r)==Math.abs(x[i]-t)) //to check if any queen take place in vertical or horizontal line

return false;

}

return true;

}

public void print(int[] y,int n){ //print the possible way

System.out.println();

System.out.println("another posible way");

System.out.println();

for (int i=0;i<n;i++){//n or y.length

System.out.print(y[i]+"|");

}

System.out.println();

System.out.println("board");

}

public void board(int[] y,int n){ //command for print chess board

for(int i=0;i<n;i++){

System.out.println();

for(int j=0;j<n;j++){

if(j==y[i]){

System.out.print("Q"+"|");}

else{

System.out.print("*"+"|");}

}

System.out.println();

for(int k=0;k<2*n;k++){

System.out.print("-");}

}

public static void main(String arg[]){ //main method head of the program

Scanner p=new Scanner(System.in); // to take the input from outside

System.out.println("enter your board length");

System.out.println();

int r=p.nextInt(); //to assign the value to r that take from outside

System.out.println("your possible ways are");

quen x=new quen(); //to create a new instance

x.Nquens(0,r); //call the method

}

Result for above coding

enter your board length
4

your possible ways are
Nquens          (0,4)
canplace        (0,0)
        yes     x[0]=0

Nquens          (1,4)
canplace        (1,0)
0==0    1==0
              no
canplace        (1,1)
0==1    1==1
                no
canplace        (1,2)
0==2    1==2
        yes     x[1]=2

Nquens          (2,4)
canplace        (2,0)
0==0    2==0
                no
canplace        (2,1)
0==1    2==1
2==1    1==1
                no
canplace        (2,2)
0==2    2==2
                no
canplace        (2,3)
0==3    2==3
2==3    1==1
                no
                no
canplace        (1,3)
0==3    1==3
        yes     x[1]=3

Nquens          (2,4)
canplace        (2,0)
0==0    2==0
                no
canplace        (2,1)
0==1    2==1
3==1    1==2
        yes     x[2]=1

Nquens          (3,4)
canplace        (3,0)
0==0    3==0
                no
canplace        (3,1)
0==1    3==1
3==1    2==2
                no
canplace        (3,2)
0==2    3==2
3==2    2==1
1==2    1==1
                no
canplace        (3,3)
0==3    3==3
                no
                no
canplace        (2,2)
0==2    2==2
                no
canplace        (2,3)
0==3    2==3
3==3    1==0
                no
                no
                no
canplace        (0,1)
        yes     x[0]=1

Nquens          (1,4)
canplace        (1,0)
1==0    1==1
                no
canplace        (1,1)
1==1    1==0
                no
canplace        (1,2)
1==2    1==1
                no
canplace        (1,3)
1==3    1==2
        yes     x[1]=3

Nquens          (2,4)
canplace        (2,0)
1==0    2==1
3==0    1==3
        yes     x[2]=0

Nquens          (3,4)
canplace        (3,0)
1==0    3==1
3==0    2==3
0==0    1==0
                no
canplace        (3,1)
1==1    3==0
                no
canplace        (3,2)
1==2    3==1
3==2    2==1
0==2    1==2
        yes     x[3]=2

posible way
1|3|0|2|
board

*|Q|*|*|
--------
*|*|*|Q|
--------
Q|*|*|*|
--------
*|*|Q|*|
--------                no
canplace        (3,3)
1==3    3==2
3==3    2==0
                no
                no
canplace        (2,1)
1==1    2==0
                no
canplace        (2,2)
1==2    2==1
3==2    1==1
                no
canplace        (2,3)
1==3    2==2
                no
                no
                no
canplace        (0,2)
        yes     x[0]=2

Nquens          (1,4)
canplace        (1,0)
2==0    1==2
        yes     x[1]=0

Nquens          (2,4)
canplace        (2,0)
2==0    2==2
                no
canplace        (2,1)
2==1    2==1
0==1    1==1
                no
canplace        (2,2)
2==2    2==0
                no
canplace        (2,3)
2==3    2==1
0==3    1==3
        yes     x[2]=3

Nquens          (3,4)
canplace        (3,0)
2==0    3==2
0==0    2==0
                no
canplace        (3,1)
2==1    3==1
0==1    2==1
3==1    1==2
        yes     x[3]=1

posible way
2|0|3|1|
board

*|*|Q|*|
--------
Q|*|*|*|
--------
*|*|*|Q|
--------
*|Q|*|*|
--------                no
canplace        (3,2)
2==2    3==0
                no
canplace        (3,3)
2==3    3==1
0==3    2==3
3==3    1==0
                no
                no
                no
canplace        (1,1)
2==1    1==1
                no
canplace        (1,2)
2==2    1==0
                no
canplace        (1,3)
2==3    1==1
                no
                no
canplace        (0,3)
        yes     x[0]=3

Nquens          (1,4)
canplace        (1,0)
3==0    1==3
        yes     x[1]=0

Nquens          (2,4)
canplace        (2,0)
3==0    2==3
0==0    1==0
                no
canplace        (2,1)
3==1    2==2
                no
canplace        (2,2)
3==2    2==1
0==2    1==2
        yes     x[2]=2

Nquens          (3,4)
canplace        (3,0)
3==0    3==3
                no
canplace        (3,1)
3==1    3==2
0==1    2==1
2==1    1==1
                no
canplace        (3,2)
3==2    3==1
0==2    2==2
                no
canplace        (3,3)
3==3    3==0
                no
                no
canplace        (2,3)
3==3    2==0
                no
                no
canplace        (1,1)
3==1    1==2
        yes     x[1]=1

Nquens          (2,4)
canplace        (2,0)
3==0    2==3
1==0    1==1
                no
canplace        (2,1)
3==1    2==2
                no
canplace        (2,2)
3==2    2==1
1==2    1==1
                no
canplace        (2,3)
3==3    2==0
                no
                no
canplace        (1,2)
3==2    1==1
                no
canplace        (1,3)
3==3    1==0
                no
                no