The following method demonstrates how to reverse the elements of one array into another:

public static void reverseArray(int[] source, int[] destination) {
    for (int i = source.length - 1, j = 0; i >= 0; i--, j++) {
        destination[j] = source[i];
    }
}

This approach uses two pointers: one starting at the end of the source array and the other at the beginning of the destination array, effectively copying elements in reverse order.

Working with Two-Dimensional Arrays

Below is an example showing how to declare and iterate through a 2D array:

int[][] matrix = {{1, 2}, {2, 3}, {3, 4}, {4, 5}};

System.out.println(matrix.length); // Outputs: 4
System.out.println(matrix[0].length); // Outputs: 2
System.out.println("==================");

for (int row = 0; row < matrix.length; row++) {
    for (int col = 0; col < matrix[row].length; col++) {
        System.out.print(matrix[row][col] + " ");
    }
    System.out.println();
}
/*
    Output:
    1 2 
    2 3 
    3 4 
    4 5 
*/

Utilizing the Arrays Class

The Arrays class provides useful utility methods for handling arrays:

int[] numbers = {1, 2, 343, 65645, 77777, 12};
System.out.println(numbers); // Prints hash code representation
System.out.println(Arrays.toString(numbers));
// Output: [1, 2, 343, 65645, 77777, 12]

Arrays.sort(numbers);
System.out.println(Arrays.toString(numbers));
// Output: [1, 2, 12, 343, 65645, 77777]

• toString() converts an array into a reaadble string format.
• sort() arranges the elements in ascending order.
• fill() assigns a specified value to a range within the array (left inclusive, right exclusive).

int[] data = {2, 4, 1, 6, 3, 5};
Arrays.fill(data, 2, 4, 0);
System.out.println(Arrays.toString(data));
// Output: [2, 4, 0, 0, 3, 5]

Arrays.fill(data, 0);
System.out.println(Arrays.toString(data));
// Output: [0, 0, 0, 0, 0, 0]

Bubble Sort Implementation and Optimization

Here's a standard implementation of the bubble sort algorithm along with an optimized version:

public static void bubbleSort(int[] arr) {
    for (int round = 0; round < arr.length - 1; round++) {
        for (int index = 0; index < arr.length - 1 - round; index++) {
            if (arr[index] > arr[index + 1]) {
                int temp = arr[index];
                arr[index] = arr[index + 1];
                arr[index + 1] = temp;
            }
        }
    }
}

public static void bubbleSortOptimized(int[] arr) {
    boolean swapped = false;
    int temp = 0;
    for (int round = 0; round < arr.length - 1; round++) {
        swapped = false;
        for (int index = 0; index < arr.length - 1 - round; index++) {
            if (arr[index] > arr[index + 1]) {
                temp = arr[index];
                arr[index] = arr[index + 1];
                arr[index + 1] = temp;
                swapped = true;
            }
        }
        if (!swapped) {
            break;
        }
    }
}