How to sort integer array in ascending and descending order using lambda only in java

WhiteWalker :

int[] arr2 = new int[] {54, 432, 53, 21, 43};

I am using this to sort but it is giving an error.

Arrays.sort(arr2, (a, b) -> a - b);

This is also giving an error.

arr2.sort((a, b) -> a - b);

Naman :

You could sort the input of type Integer[] as :

Integer[] arr2 = new Integer[] {54,432,53,21,43};
Arrays.sort(arr2, Comparator.reverseOrder());

or possibly with primitive types as :

int[] arr2 = new int[]{54, 432, 53, 21, 43};
int[] sortedArray = Arrays.stream(arr2)
        .boxed()
        .sorted(Comparator.reverseOrder()) // just use 'sorted()' for ascending order
        .mapToInt(Integer::intValue)
        .toArray();

or further using a trick from one of the existing answers (do note that it should be cautiously used with boundary values though) :

int[] sortedArray = Arrays.stream(arr2)
        .map(i -> -i).sorted().map(i -> -i) // just use 'sorted()' for ascending order
// Edit - use map(i -> ~i).sorted().map(i -> ~i) to be safe from the issue with Integer.MIN_VALUE
        .toArray();

Edit: For an in-place ascending order sort, you just need to perform :

int[] arr2 = new int[]{54, 432, 53, 21, 43};
Arrays.sort(arr2);