Can't convert String[] to int[],Why?

Question

import java.util.*;

public class Main {
public static void main(String[] args) {
Scanner sc=new Scanner(System.in);
int a=sc.nextInt();
String b=sc.nextLine();
String[]b1=b.split(" ");
int[] arr = new int[b1.length];
for (int i = 0; i < b1.length; i++) {
arr[i] = Integer.parseInt(b1[i]);
}

}
}

Answer 1

For a perfect input, the problem lies because of the "int a = sc.nextInt()" statement.

By removing it, the program works nicely.

As after the "nextInt()", the program is accepting a null string "" as the error displays.

Answer 2

What input is being provided? If it's a sentence then the String won't convert to an Int.