2D Arrays in Java Quiz

How do you declare a 2D array in Java?

• `int[][] array2D;`

• `int array2D[][];`

• `int[2][2] array2D;`

• Both A and B are correct.

Which of the following is the correct way to initialize a 2D array in Java?

• `int[][] array2D = new int[2][2];`

• `int array2D[][] = {{1, 2}, {3, 4}};`

• `int[][] array2D = {{1, 2}, {3, 4}};`

• All of the above.

How do you access the first element in the second row of a 2D array named `array2D`?

• `array2D[1][0];`

• `array2D[0][1];`

• `array2D[2][1];`

• `array2D[1][1];`

What does `array2D.length` return for a 2D array named `array2D`?

• The number of columns in the array.

• The number of rows in the array.

• The total number of elements in the array.

• The length of the first row.

How would you iterate through all elements of a 2D array named `array2D` using a nested for loop?

• `for(int i = 0; i < array2D.length; i++) { for(int j = 0; j < array2D[i].length; j++) { // access element } }`

• `for(int i = 0; i < array2D.length; i++) { for(int j = 0; j < array2D.length; j++) { // access element } }`

• `for(int i = 0; i < array2D[0].length; i++) { for(int j = 0; j < array2D.length; j++) { // access element } }`

• `for(int i = 0; i < array2D.length; i++) { for(int j = 0; j < array2D[0].length; j++) { // access element } }`

What is the correct way to pass a 2D array named `array2D` to a method in Java?

• `public void processArray(int[][] array2D) { // process array }`

• `public void processArray(int array2D[][]) { // process array }`

• `public void processArray(int[] array2D[]) { // process array }`

• All of the above.

Which of the following statements will correctly create a 2D array with 3 rows and 2 columns?

• `int[][] array2D = new int[3][2];`

• `int array2D[][] = new int[2][3];`

• `int[] array2D = new int[3][2];`

• `int[][] array2D = new int[][3];`

How do you initialize a 2D array with different column sizes in Java?

• `int[][] array2D = new int[2][]; array2D[0] = new int[3]; array2D[1] = new int[2];`

• `int[][] array2D = {{1, 2, 3}, {4, 5}};`

• `int[][] array2D = new int[][3];`

• Both A and B are correct.

What is the output of `array2D[0].length` if `array2D` is initialized as follows: `int[][] array2D = {{1, 2}, {3, 4, 5}};`?

• 2

• 3

• 5

• An error occurs.

Which of the following is true about a 2D array in Java?

• It is an array of arrays.

• All rows must have the same number of columns.

• It cannot contain different types of elements.

• It is always square.