Java Multi-Dimensional Arrays

dataType[][] arrayName; // Declaration
arrayName = new dataType[rows][columns]; // Allocation

1 2	dataType[][] arrayName; // Declaration arrayName = new dataType[rows][columns]; // Allocation

Or combined:

dataType[][] arrayName = new dataType[3][4]; // 3 rows, 4 columns

1	dataType[][] arrayName = new dataType[3][4]; // 3 rows, 4 columns

public class Main {
public static void main(String[] args) {
int[][] matrix = {
{1, 2, 3},
{4, 5, 6},
{7, 8, 9}
};

System.out.println(matrix[0][1]); // 2
System.out.println(matrix[2][2]); // 9
}
}

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public class Main {

public static void main(String[] args) {

int[][] matrix = {

{1, 2, 3},

{4, 5, 6},

{7, 8, 9}

};

System.out.println(matrix[0][1]); // 2

System.out.println(matrix[2][2]); // 9

}

public class Main {
public static void main(String[] args) {
int[][] matrix = {
{1, 2, 3},
{4, 5, 6},
{7, 8, 9}
};

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

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public class Main {

public static void main(String[] args) {

int[][] matrix = {

{1, 2, 3},

{4, 5, 6},

{7, 8, 9}

};

for (int i = 0; i < matrix.length; i++) { // rows

for (int j = 0; j < matrix[i].length; j++) { // columns

System.out.print(matrix[i][j] + " ");

}

System.out.println();

}

public class Main {
public static void main(String[] args) {
int[][] matrix = {
{1, 2, 3},
{4, 5, 6},
{7, 8, 9}
};

int sum = 0;

for (int[] row : matrix) {
for (int value : row) {
sum += value;
}
}

System.out.println("Sum of all elements: " + sum);
}
}

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public class Main {

public static void main(String[] args) {

int[][] matrix = {

{1, 2, 3},

{4, 5, 6},

{7, 8, 9}

};

int sum = 0;

for (int[] row : matrix) {

for (int value : row) {

sum += value;

}

System.out.println("Sum of all elements: " + sum);

}

Sum of all elements: 45

public class Main {
public static void main(String[] args) {
int[][] matrix = {
{1, 2, 3},
{4, 5, 6},
{7, 8, 9}
};

for (int i = 0; i < matrix.length; i++) {
int rowSum = 0;
for (int j = 0; j < matrix[i].length; j++) {
rowSum += matrix[i][j];
}
System.out.println("Sum of row " + i + ": " + rowSum);
}
}
}

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public class Main {

public static void main(String[] args) {

int[][] matrix = {

{1, 2, 3},

{4, 5, 6},

{7, 8, 9}

};

for (int i = 0; i < matrix.length; i++) {

int rowSum = 0;

for (int j = 0; j < matrix[i].length; j++) {

rowSum += matrix[i][j];

}

System.out.println("Sum of row " + i + ": " + rowSum);

}

Sum of row 0: 6

Sum of row 1: 15

Sum of row 2: 24

public class Main {
public static void main(String[] args) {
int[][] matrix = {
{1, 2, 3},
{4, 5, 6},
{7, 8, 9}
};

int columns = matrix[0].length;

for (int j = 0; j < columns; j++) {
int colSum = 0;
for (int i = 0; i < matrix.length; i++) {
colSum += matrix[i][j];
}
System.out.println("Sum of column " + j + ": " + colSum);
}
}
}

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public class Main {

public static void main(String[] args) {

int[][] matrix = {

{1, 2, 3},

{4, 5, 6},

{7, 8, 9}

};

int columns = matrix[0].length;

for (int j = 0; j < columns; j++) {

int colSum = 0;

for (int i = 0; i < matrix.length; i++) {

colSum += matrix[i][j];

}

System.out.println("Sum of column " + j + ": " + colSum);

}

Sum of column 0: 12

Sum of column 1: 15

Sum of column 2: 18

public class Main {
public static void main(String[] args) {
boolean[][] seats = new boolean[3][5]; // 3 rows, 5 seats per row

// Book some seats
seats[0][1] = true;
seats[1][3] = true;

for (int i = 0; i < seats.length; i++) {
for (int j = 0; j < seats[i].length; j++) {
System.out.print((seats[i][j] ? "[X]" : "[O]") + " ");
}
System.out.println();
}
}
}

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public class Main {

public static void main(String[] args) {

boolean[][] seats = new boolean[3][5]; // 3 rows, 5 seats per row

// Book some seats

seats[0][1] = true;

seats[1][3] = true;

for (int i = 0; i < seats.length; i++) {

for (int j = 0; j < seats[i].length; j++) {

System.out.print((seats[i][j] ? "[X]" : "[O]") + " ");

}

System.out.println();

}

[O] [X] [O] [O] [O]

[O] [O] [O] [X] [O]

[O] [O] [O] [O] [O]

Java Multi-Dimensional Arrays

Java Multi-Dimensional Arrays (2D Arrays)

1. Declaration and Initialization

Syntax:

Example 1: 2D Array Declaration and Initialization

2. Looping Through a 2D Array

Using nested for loops:

3. Sum of All Elements in 2D Array

4. Row-wise Sum

5. Column-wise Sum

6. Real-Life Example: Seat Booking in Theater

🧠 Key Points

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Java Multi-Dimensional Arrays

Java Multi-Dimensional Arrays (2D Arrays)

1. Declaration and Initialization

Syntax:

Example 1: 2D Array Declaration and Initialization

2. Looping Through a 2D Array

Using nested for loops:

3. Sum of All Elements in 2D Array

4. Row-wise Sum

5. Column-wise Sum

6. Real-Life Example: Seat Booking in Theater

🧠 Key Points

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