2d Array Input In Java

4 min read Jun 22, 2024

2D Array Input in Java

A 2D array in Java is essentially an array of arrays. It allows you to store data in a tabular format, similar to a spreadsheet. Each element in the 2D array can be accessed using two indices: the row index and the column index.

Declaring and Initializing 2D Arrays

You can declare and initialize a 2D array in Java in two ways:

1. Static Initialization:

int[][] matrix = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}};

This method initializes the array with specific values directly during declaration.

2. Dynamic Initialization:

int[][] matrix = new int[3][3];

This method only declares the size of the array. You can then assign values to individual elements later using nested loops.

Inputting Values into a 2D Array

To input values into a 2D array from the user, you can use nested loops. Here's how:

Get the dimensions of the array: Ask the user to input the number of rows and columns.
Create the array: Use the new keyword to create the array with the specified dimensions.
Use nested loops to get the input: The outer loop iterates through each row, and the inner loop iterates through each column in that row. Inside the inner loop, use Scanner to get the input from the user and assign it to the corresponding array element.

import java.util.Scanner;

public class TwoDArrayInput {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        System.out.print("Enter the number of rows: ");
        int rows = scanner.nextInt();
        System.out.print("Enter the number of columns: ");
        int columns = scanner.nextInt();

        int[][] matrix = new int[rows][columns];

        System.out.println("Enter the elements of the matrix:");
        for (int i = 0; i < rows; i++) {
            for (int j = 0; j < columns; j++) {
                System.out.print("Enter element at [" + i + "][" + j + "]: ");
                matrix[i][j] = scanner.nextInt();
            }
        }

        System.out.println("The matrix is:");
        for (int i = 0; i < rows; i++) {
            for (int j = 0; j < columns; j++) {
                System.out.print(matrix[i][j] + " ");
            }
            System.out.println();
        }
    }
}

Example Usage:

This code will:

Prompt the user to enter the number of rows and columns.
Create a 2D array with those dimensions.
Prompt the user to enter each element of the array.
Display the inputted 2D array.

Conclusion

Understanding how to input values into 2D arrays is crucial for many Java programming tasks. By using nested loops and a Scanner object, you can effectively create and manipulate these structures to store and process data in a two-dimensional format.

2d Array Input In Java