How to declare/initialize 2D arrays

// Boiler Plate Code
public class Main {
    public static void main(String[] args) {

        */ (Intialize Array Here) */

        // Display Array Code below
        for(int i = 0; i < myArray.length; i++) {
            for (int j = 0; j < myArray[i].length; j++) {
                System.out.print(myArray[i][j] + " ");
            }
            System.out.println();
        }
    }
}

Main.main(null)

|           */ (Intialize Array Here) */

illegal start of expression



|           */ (Intialize Array Here) */

illegal start of expression



|           */ (Intialize Array Here) */

',', ')', or '[' expected



|           */ (Intialize Array Here) */

';' expected

1) All in one

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

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]]
//Hack - Dinesh Sahai

//Method 1
String [][] myTable = {
    {"Dinesh", "Tanay"},
    {"Nisarg", "Imaad"}
};

//Method 2
String [][] myNewTable = new String [2][2];
myNewTable[0][0] = "Dinesh";
myNewTable[0][1] = "Tanay";
myNewTable[1][0] = "Nisarg";
myNewTable[1][1] = "Imaad";

//Method 3
String[][] matrix = new String[2][2];
int value = 1; 

for (int i = 0; i < matrix.length; i++) {  
    for (int j = 0; j < matrix[i].length; j++) {  
        if (value == 1) {
            matrix[i][j] = "Dinesh";
        } else if (value == 2) {
            matrix[i][j] = "Nisarg";
        } else if (value == 3) {
            matrix[i][j] = "Tanay";
        } else if (value == 4) {
            matrix[i][j] = "Imaad";
        }
        value++; 
    }
}

Imaad