Sort arrays of primitive types in descending order

Question

I've got a large array of primitive types (double). How do I sort the elements in descending order? Unfortunately the Java API doesn't support sorting of primitive types with a Comparator. The first approach that probably comes to mind is to convert it to a list of objects (boxing): double[] array = new double[1048576]; Arrays.stream(array).boxed().sorted(Collections.reverseOrder())… However, boxing each primitive in the array is too slow and causes a lot of GC pressure! Another approach would be to sort and then reverse: double[] array = new double[1048576]; ... Arrays.sort(array); // reverse the array for (int i = 0; i < array.length / 2; i++) { // swap the elements double temp = array[i]; array[i] = array[array.length - (i + 1)]; array[array.length - (i + 1)] = temp; } This approach is also slow - particularly if the array is already sorted quite well. What's a better alternative? JavaScript questions and answers, JavaScript questions pdf, JavaScript question bank, JavaScript questions and answers pdf, mcq on JavaScript pdf, JavaScript questions and solutions, JavaScript mcq Test , Interview JavaScript questions, JavaScript Questions for Interview, JavaScript MCQ (Multiple Choice Questions)

Answer 1

I think it would be best not to re-invent the wheel and use Arrays.sort(). Yes, I saw the "descending" part. The sorting is the hard part, and you want to benefit from the simplicity and speed of Java's library code. Once that's done, you simply reverse the array, which is a relatively cheap O(n) operation. Here's some code I found to do this in as little as 4 lines: for (int left=0, right=b.length-1; left<right; left++, right--) { // exchange the first and last int temp = b[left]; b[left] = b[right]; b[right] = temp; }