Question

A file named 'input.txt' contains a list of words. Write a program that reads the content of the file one word at a time. Check if the word is a palindrome. If the word is a palindrome write it at the output file Output'.

Answer 1

Answer:

// here is code in java.

import java.io.*;

import java.util.Scanner;

class Main{  

    // function to check a word is palindrome or not

 private static boolean is_Palind(String str1)

 {

     // if length of String is 0 or 1

   if(str1.length() == 0 || str1.length() == 1)

   {

     return true;

   }

   else

   {

       // recursively check the word is palindrome or not

     if(str1.charAt(0) == str1.charAt(str1.length()-1))

     {

       return is_Palind(str1.substring(1,str1.length()-1));

     }

     

     else

     {

       return false;

     }

   }

 }

// driver function

 public static void main(String[] args)

 {// variable to store word

   String word;

   // BufferedWriter object

   BufferedWriter buff_w = null;

   // FileWriter object

   FileWriter file_w = null;

   // Scanner object

   Scanner sc = null;

   try

   {

       // read the input file name

     sc = new Scanner(new File("input.txt"));

     // output file

     file_w = new FileWriter("output.txt");

     // create a buffer in output file

     buff_w = new BufferedWriter(file_w);

     

     // read each word of input file

     while(sc.hasNext())

     {

       word = sc.next();

     // check word is palindrome or not

       if(is_Palind(word))

       {

           // if word is palindrome then write it in the output file

         buff_w.write(word);

         buff_w.write("\n");

       }

     }

     // close the buffer

     buff_w.close();

     // close the input file

     sc.close();

   }

   // if there is any file missing

   catch (FileNotFoundException e) {

     System.out.println("not able to read file:");

   }

   // catch other Exception

   catch (IOException e) {

     e.printStackTrace();

   }

 }

}

Explanation:

Create a scanner class object to read the word from "input.txt" file.Read a word  from input file and check if it is palindrome or not with the help of is_Palind() function.it will recursively check whether string is palindrome or not. If it is  palindrome then it will written in the output.txt file with the help of BufferedWriter  object. This will continue for all the word of input file.

Input.txt

hello world madam

level welcome

rotor redder

output.txt

madam

level

rotor

redder