6.8. 2D Array Example: Matrix Print

A two-dimensional (2D) array can be visualized as a table or matrix. It consists of rows and columns where each element can be accessed using two indices.

A 2D array is essentially an array of arrays. Each inner array represents a row, while the outer array is the entire matrix. The elements are accessed using two indices: the first index (i) for the row number and the second index (j) for the column number.

Think of a chessboard, which has 8 rows and 8 columns. Each square on the board can be identified by its row number (1 to 8) and column number (1 to 8). Similar to that, elements in a 2D array are identified by two indices.

In the example, the 2D array is initialized as follows:

int[][] mat = {
    {1, 2},
    {3, 4}
};

The initialization of the 2D array is done using nested curly braces. Each pair of braces represents a row of the matrix. In this example, the first row contains the elements 1 and 2, and the second row contains the elements 3 and 4.

This is similar to creating a seating plan for a theater. You list the rows first (row 1, row 2, etc.), and under each row, you specify the seats (seat 1, seat 2, etc.) available in that row.

To print the elements of the array, nested loops are used:

for (int i = 0; i < 2; i++) {
    for (int j = 0; j < 2; j++) {
        System.out.print(mat[i][j] + " ");
    }
    System.out.println();
}

Two nested for loops are used to access each element of the 2D array. The outer loop iterates through the rows (i) while the inner loop iterates through the columns (j). For each element accessed, it is printed out, followed by a space to keep the formatting consistent. After printing a complete row, a separate new line is printed to start the next row on a new line.

Imagine printing out the seating arrangement for a wedding. You write down all the guests in each row one after the other, and once you finish a row, you start a new line to begin listing the next row. This approach helps keep things organized and visually clear.

The output of the program will display the matrix:

1 2
3 4

After executing the print statement in the loops, the output shows the elements of the matrix arranged in two rows. The first printed line corresponds to the first row of the 2D array, and the second printed line corresponds to the second row.

Think of displaying a scoreboard for a game, where each row shows the scores of different teams. The output visually represents how scores are structured in the context of the ongoing match.

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