Populate a 2D Array Using Scanner and a Text File in Java

Are you looking to enhance your Java programming skills by learning how to populate a 2D array using a scanner and a text file? If so, you’ve come to the right place. In this article, I’ll guide you through the process step by step, ensuring that you understand each aspect of the task. By the end, you’ll be able to implement this technique in your own projects.

Understanding the Basics

Before diving into the code, it’s essential to understand the basics of what we’re trying to achieve. A 2D array is essentially an array of arrays, where each element is itself an array. In Java, you can create a 2D array by specifying the number of rows and columns. A scanner is a class in Java that provides methods for reading input from various sources, such as a file. By combining these two concepts, we can populate a 2D array with data from a text file.

Setting Up the Project

Start by creating a new Java project in your preferred IDE. You’ll need to have Java installed on your computer to compile and run the code. Once your project is set up, create a new Java class, for example, “ArrayPopulator.java”.

Creating the 2D Array

In your Java class, declare a 2D array with the desired number of rows and columns. For example:

int[][] myArray = new int[5][3];

This creates a 2D array with 5 rows and 3 columns. You can adjust the dimensions according to your needs.

Reading from a Text File

Next, you’ll need to read the data from a text file. Create a text file with the desired data, for example, “data.txt”. Each line in the file should contain the values for a row in the 2D array, separated by commas. For example:

1,2,3    4,5,6    7,8,9    10,11,12    13,14,15

Now, let’s write the code to read this file and populate the 2D array.

The Code

Here’s the complete code to read the text file and populate the 2D array:

import java.io.File;    import java.io.FileNotFoundException;    import java.util.Scanner;    public class ArrayPopulator {        public static void main(String[] args) {            int[][] myArray = new int[5][3];            File file = new File("data.txt");            try (Scanner scanner = new Scanner(file)) {                int row = 0;                while (scanner.hasNextLine()) {                    String line = scanner.nextLine();                    String[] values = line.split(",");                    for (int i = 0; i < values.length; i++) {                        myArray[row][i] = Integer.parseInt(values[i]);                    }                    row++;                }            } catch (FileNotFoundException e) {                System.out.println("File not found: " + e.getMessage());            }            // Print the populated array            for (int[] row : myArray) {                for (int value : row) {                    System.out.print(value + " ");                }                System.out.println();            }        }    }

This code reads the file "data.txt" line by line, splits each line into an array of strings using the comma as a delimiter, and then converts each string to an integer. The integers are then stored in the corresponding position in the 2D array.

Understanding the Output

When you run the code, you should see the following output:

1 2 3     4 5 6     7 8 9     10 11 12     13 14 15

This output represents the populated 2D array. Each row is printed on a new line, and each value in the row is separated by a space.

Conclusion

By following this guide, you should now have a clear understanding of how to populate a 2D array using a scanner and a text file in Java. This technique can