I'm working on this project using Arrays. I have a method called createRandomIntArray that creates an array. This method is meant to return the Array in descending order. I have been able to do just that but I want to know if there is a more effective way to write this method than the way I wrote it. I have my code below.

    public static int[] createRandomIntArray(int n) {
        Random random = new Random();

        int[] result = new int[n];
        for (int i = 0; i < n; i  ) {
            result[i] = random.nextInt(n);
        }
        Arrays.sort(result);

        for (int i = 0; i < result.length / 2; i  ) {
            int temp = result[i];
            result[i] = result[result.length - i - 1];
            result[result.length - i - 1] = temp;
        }
        return result;
    }

CodePudding user response：

You could avoid reversing the sorted array by directly sorting reverse order:

Arrays.sort(result, Comparator.reverseOrder());

As mentioned in the comments one could use Random.ints(…) if you’re not tied to using arrays:

random.ints(n, 0, n).boxed().sorted(Comparator.reverseOrder()).mapToInt(i -> i).toArray(int[]::new);

CodePudding user response：

public class SortDes {  
    public static void main(String[] args) { 

        int [] arr = new int [] {5, 2, 8, 7, 1};   
        int temp = 0;  
          
        System.out.println("Elements of original array: ");  
        for (int i = 0; i < arr.length; i  ) {   
            System.out.print(arr[i]   " ");  
        }  
           
        for (int i = 0; i < arr.length; i  ) {   
            for (int j = i 1; j < arr.length; j  ) {   
               if(arr[i] < arr[j]) {  
                   temp = arr[i];  
                   arr[i] = arr[j];  
                   arr[j] = temp;  
               }   
            }   
        }  
          
        System.out.println();  
          
        System.out.println("Elements of array sorted in descending order: ");  
        for (int i = 0; i < arr.length; i  ) {   
            System.out.print(arr[i]   " ");  
        }  
    }  
}

CodePudding user response：

There's an alternative which is using Stream.

Arrays.stream(result).sorted(Comparator.reverseOrder());

CodePudding user response：

Using Java Streams

private static int[] createRandomIntArray(int n) {
    return ThreadLocalRandom.current().ints()   // Stream of random ints
        .limit(n)                               // Limit the stream to n values
        .boxed()                                // Convert to Stream of Integer Objects for reverse sorting
        .sorted(Collections.reverseOrder())     // Sort in reverse Order
        .mapToInt(Integer::intValue)            // Map back to primitive ints
        .toArray();                             // as Array
}