Question

public class File_In_36

{

   private String filename;

   public int[][] matrix()

   {

      // 1. matrix will call scan_File to determine whether or not the file

      // name entered by the user actually exists

      // 2. matrix will call size_matrix to determine the number of integers

      // in the input file and set the instance variable matrix_size to that

      // number

      // 3. matrix will call check_square to determine whether or not matrix_size

      // has the exact number of integers required for a square matrix

      // {4, 9, 16, 25, 36 ...}

      // 4. If the matrix is square, method matrix will call form_matix and return

      // a reference to a two dimensional square array; else it will return null

       System.out.println("The filename passed to matrix = " + filename);        

         int[][] dummy = new int[4][4];

         return dummy;

   }

}

Answer 1

CODE:

import java.util.*;

import java.io.*;

public class a{

public static void main(String args[]){

File_In_36 f = new File_In_36();

int arr[][]=f.matrix();

if(arr!=null){

f.print_matrix(arr);

}

}

}

class File_In_36

{

private String fileName;

private int matrix_size;

public int[][] matrix()

{

// 1. matrix will call scan_File to determine whether or not the file

// name entered by the user actually exists

// 2. matrix will call size_matrix to determine the number of integers

// in the input file and set the instance variable matrix_size to that

// number

// 3. matrix will call check_square to determine whether or not matrix_size

// has the exact number of integers required for a square matrix

// {4, 9, 16, 25, 36 ...}

// 4. If the matrix is square, method matrix will call form_matix and return

// a reference to a two dimensional square array; else it will return null

scan_File();

System.out.println("The filename passed to matrix = " + fileName);   

int count=size_matrix();

if(check_square(count)){

int arr[][]=form_matix();

return arr;

}

else{

System.out.println("The numbers in the file doesnot form a square matrix");

return null;

}

}

public void print_matrix(int arr[][]){

System.out.println();

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

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

System.out.print(arr[i][j]+" ");

}

System.out.println();

}

}

public int[][] form_matix(){

int arr[][]=new int[matrix_size][matrix_size];

File f=null;

Scanner s=null;

try{

f=new File(fileName);

s=new Scanner(f);

}

catch(Exception e){

System.exit(0);

}

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

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

arr[i][j]=s.nextInt();

}

}

return arr;

}

public void scan_File(){

Scanner sc = new Scanner(System.in);

File f=null;

do{

if(f!=null)System.out.println("File doesnot exist. Enter again: ");

else System.out.println("Enter fileName: ");

fileName = sc.next();

fileName = "./"+fileName;

f = new File(fileName);

}while(!f.exists() || f.isDirectory());

}

public int size_matrix(){

int count=0;

File f=null;

Scanner s=null;

try{

f=new File(fileName);

s=new Scanner(f);

}

catch(Exception e){

System.exit(0);

}

System.out.println("Countinh numbers");

while(s.hasNext()){

count ++;

s.nextInt();

}

System.out.println(count);

matrix_size= (int)Math.sqrt(count);

return count;

}

public boolean check_square(int n){

double sr = Math.sqrt(n);

  

return ((sr - Math.floor(sr)) == 0);

}

}

Sample Output:

radas-macOS:Desktop radas$ javac a.java
radas-macOS:Desktop radas$ java a
Enter fileName:
test.txt
The filename passed to matrix = ./test.txt
Countinh numbers
9

1 2 3
4 5 6
7 8 9

Contents of file test.txt:

1
2
3
4
5
6
7
8
9