Answer to Question #293385 in Java | JSP | JSF for jeffy

Question

In this task, you are being asked to write methods that manipulate arrays in Java.

1. Write a method called swapFirstAndLastRow which will take a two-dimensional

integer array as argument and swap all the values of first row and last row with each

other.

You may use the following header for this method:

static void swapFirstAndLastRow(int[][] array)

For example, if we pass the following two-dimensional array to this method:

5 7 9 4 3 1

2 4 9 7 6 5

3 6 8 7 9 4

1 9 7 5 6 3

Then the array will become:

1 9 7 5 6 3

2 4 9 7 6 5

3 6 8 7 9 4

5 7 9 4 3 1

2. Write a third method called printArray which will take a two-dimensional integer

array as argument and prints all elements of array. The method should print each row line

by line.

You may use the following header for this method:

static void printArray (int[][] array)

Take two numbers from the user as the size of rows and columns of the array and call the

methods in the following order:

 printArray()

 swapFirstAndLastRow()

 printArray

Answer 1

public class App {


	/**
	 * The start point of the program
	 * 
	 * @param args
	 * 
	 */
	public static void main(String[] args) {
		int[][] array = { { 5, 7, 9, 4, 3, 1 }, { 2, 4, 9, 7, 6, 5 }, { 3, 6, 8, 7, 9, 4 }, { 1, 9, 7, 5, 6, 3 } };


		printArray(array);
		swapFirstAndLastRow(array);
		System.out.println();
		printArray(array);
	}


	static void swapFirstAndLastRow(int[][] array) {
		int[] arrayTemp = array[0];
		array[0] = array[array.length - 1];
		array[array.length - 1] = arrayTemp;
	}


	static void printArray(int[][] array) {
		for (int i = 0; i < array.length; i++) {
			for (int j = 0; j < array[0].length; j++) {
				System.out.print(array[i][j] + " ");
			}
			System.out.println();
		}
	}
}