Question

Create a java project.

Create a class called cls2DarrayProcessor.java. with the following:

1. Reads numbers from a pre-defined text file.

A: Text file name should be data.txt

B: Text file should be in the same workspace directory of your project's folder

C: Text file name should be STORED in a String and called:

String strFile ='./data.txt'

2. Defines a 2-D array of integers with dimensions of 5 rows by 5 columns.
3. Inserts the data from the text file to the 2-D array following this logic:

A: If the read number matches the 2-D array columns and row numbers, then assign the read number to that array element, otherwise, assign the value 0 to that element.

4. Prints out all elements in the array: separated by a space, one row per line.

Answer 1

The below code does the above job of reading data from a file by using Scanner and reading each line separately, and modifying the 2D array with the logic above.

CODE:-

import java.io.*; //to perform basic input output operations

import java.util.Scanner; //take input from the file

class cls2DarrayProcessor { //main class

    public static void main(String args[]) throws FileNotFoundException {

        String strFile = "./data.txt";

        File file = new File(strFile);

        Scanner sc = new Scanner(file); //a Scanner object to read from the file and throws a FileNotFoundException if the file is not found

        

        int[][] A = new int[5][5]; //Create a new 2d Array of integers.

        while(sc.hasNextLine()) //while there are lines in the file by using a hasNextLine method which checks if there exists, more lines to be processes, if no then returns a false, else true

        {

            int x = Integer.parseInt(sc.nextLine()); //converts the string line to its corresponding integer

            for(int i=0; i<5; i++) //Traverse the 2D array and check if any entry in the matrix has the row number and the column number as the read integer x,if yes then assign it to that element else assign 0.

            {

                for(int j=0; j<5; j++)

                {

                    if(i == x && j == x)

                    {

                        A[i][j] = x; //row number and column number matches and thus assigned to it

                    }

                    else{

                        A[i][j] = 0; //does not match, and hence 0 is assigned

                    }

                }

            }

        }

        //Print the elements of the 2D array

        for(int i=0; i<5; i++)

        {

            System.out.printf("\n"); //print a new line for every row

            for(int j=0; j<5; j++)

            {

                System.out.printf("%d ", A[i][j]); //print the elements of the array by using printf which is a C-style formatting for printing the elements

            }

        }

    }   

}

OUTPUT:-

0 0 0 0 0
0 1 0 0 0
0 0 0 0 0
0 0 0 0 0
0 0 0 0 0

DATA.TXT:-

1

0

1

3

4

1

2

8

1

4

2

6

7

1

9

0

3

4

2

5

6

4

3

4

1