Question

Create a MergeFiles application that merges the integers ordered from low to high in two text data files into a third text data file, maintaining the order from low to high (no post merge sorts!). For example, the two files of integers could contain:

File 1: 12 23 34 45 56 67 69 123 133

File 2: 4 5 10 20 35 44 100 130 150 160 180

The application should not use an array or ArrayList to temporarily store the numbers, but should merge the two files taking one element at a time from each. After MergeFiles runs for this example, the third file should contain:

4 5 10 12 20 23 34 35 44 45 56 67 69 100 123 130 133 150 160 180

Create the two input files using a text editor with the numbers of your choice. Be sure to employ proper exception handling for the file I/O. Use at least one try-catch statement that properly handles exceptions.

Answer 1

HI, Pease find my implementation.

Please let me know in case of any issue.

import java.io.File;

import java.io.PrintWriter;

import java.util.ArrayList;

import java.util.Scanner;

public class MergeFiles {

   public static void main(String[] args) {

       Scanner sc = new Scanner(System.in);

       System.out.print("Enter first input file name: ");

       String firstFile = sc.next();

       System.out.print("Enter second input file name: ");

       String secondFile = sc.next();

       System.out.print("Enter output file name: ");

       String outputFile = sc.next();

       try{

           // opening both input file

           Scanner readFileOne = new Scanner(new File(firstFile));

           Scanner readFileTwo = new Scanner(new File(secondFile));

           // Opening file writer

           PrintWriter writeFile = new PrintWriter(new File(outputFile));

           // creating two array list

           ArrayList<Integer> firstArr = new ArrayList<>();

           ArrayList<Integer> secondArr = new ArrayList<>();

           // reading first file

           while(readFileOne.hasNextInt()){

               firstArr.add(readFileOne.nextInt());

           }

           // reading second file

           while(readFileTwo.hasNextInt()){

               secondArr.add(readFileTwo.nextInt());

           }

          

           // printing both list

           System.out.println(firstArr);

           System.out.println(secondArr);

          

           // merging two array and writing to file

           int i=0, j=0;

           while(i<firstArr.size() && j<secondArr.size()){

               if(firstArr.get(i) <= secondArr.get(j)){

                   writeFile.print(firstArr.get(i)+" ");

                   i++;

               }else{

                   writeFile.print(secondArr.get(j)+" ");

                   j++;

               }

           }

          

           // writing remaining entries of firtArr or secondArr

           while( i < firstArr.size()){

               writeFile.print(firstArr.get(i)+" ");

               i++;

           }

          

           while( j < secondArr.size()){

               writeFile.print(secondArr.get(j)+" ");

               j++;

           }

          

           // closing all files

           sc.close();

           readFileOne.close();

           readFileTwo.close();

           writeFile.close();

          

           System.out.println("File Written Successfully!!!");

       }catch(Exception e){

           System.out.println(e.getMessage());

       }

   }

}

####### file1.txt #######

12 23 34 45 56 67 69 123 133

########## file2.txt #######

4 5 10 20 35 44 100 130 150 160 180

########## mergedfile.txt $$$$$$$$$$$$$
4 5 10 12 20 23 34 35 44 45 56 67 69 100 123 130 133 150 160 180