Practice Problem in Java day 9

Today I covered the sliding window problem to calculate the maximum sum of sub array using kadane's algorithm in java

public class sumofsubarr {
static int max(int a, int b){
return a>b? a : b;
}
public static void main(String[] args) {
int[] arr={1,3,5,2,4,6};
int k=3;
int maxS=0;
int curS=0;
if (k> arr.length) System.out.println(-1);
for (int i=0;i<k;i++) {
curS += arr[i];
}
maxS=curS;
for (int i=k;i< arr.length;i++){//kadanes algorithm
curS=curS+arr[i]-arr[i-k];
maxS=max(maxS,curS);
}

    System.out.println(maxS);
}

}