Java 8 - Find Leaders in an Array

Question

I am trying to learn the features of Java 8 especially the functional programming aspect of it. So I am trying to solve a problem: Find Leaders in an Array - A leader is an element which is larger than all the elements in the array to its right.

For example:

Input Array: { 98, 23, 54, 12, 20, 7, 27 }

Output: Leaders - 27 54 98

Now, I have solved this using the usual iterative approach as shown below.

private static void findLeaders(int[] array) {
        int currentLeader = array[array.length - 1];
        System.out.println(currentLeader);
        for(int i = array.length - 1; i >= 0; i--) {
            if(array[i] > currentLeader) {
                System.out.println(array[i]);
                currentLeader = array[i];
            }
        }
    }

I tried solving it using Java 8, but I couldn't do much apart from writing this piece of code, which again had compilation error:

Function checkLeader = i ->  i > currentLeader ? i : currentLeader;

Error: Local variable currentLeader defined in an enclosing scope must be final or effectively final

Now how do I solve the same problem using the features of Java 8.

Java 8 - Find Leaders in an Array

2 Answers