Unit 8 - 2D Arrays Declaring and Initializing

12 Sep 2024 • AP CSA

Declaring, Initializing

Accessing, Updating

How to declare/initialize 2D arrays

2) Empty array and manual input with indexes

// Declare a 3x3 empty 2D array
int[][] matrix = new int[3][3];

// Assign values to the 2D array using indexes
matrix[0][0] = 1;
matrix[0][1] = 2;
matrix[0][2] = 3;
matrix[1][0] = 4;
matrix[1][1] = 5;
matrix[1][2] = 6;
matrix[2][0] = 7;
matrix[2][1] = 8;
matrix[2][2] = 9;

3) Nested For-Loop

int value = 1; // Start value
for (int i = 0; i < matrix.length; i++) {  // Outer loop for rows
    for (int j = 0; j < matrix[i].length; j++) {  // Inner loop for columns
        matrix[i][j] = value++; // Assign value and increment
    }
}

Popcorn Hack 1 (Part 1):

Intialize a 2D array of the people in your group grouped based on pairs with 3 different methods
ex Array: [[Anusha, Vibha],[Avanthika, Matthew]]

String[][] bob = new String[2][2];

bob[0][0] = "Ian";
bob[0][1] = "Srijan";
bob[1][0] = "Tarun";
bob[1][1] = "Jonathan";

Jonathan

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