Eratosthenes sieve in Java

<<algorithm

import java.util.Scanner;
public class Sieve {
  public static void main(String[] args) {
    int n,i,j;
    Scanner key=new Scanner(System.in);
    System.out.print("n = ");
    n=key.nextInt();
    if(n<2) System.out.println("Brak liczb pierwszych w podanym zakresie");
    else{
      boolean[] del = new boolean[n+1];
      for(i=2;i<=n;i++) del[i]=false;
      i=1;
      do{
        i++;
        if(!del[i]){
          j=i*i;
          while(j<=n){
            del[j]=true;
            j+=i;
          }
        }
      } while(i*i<=n);
      for(i=2;i<=n;i++) if(!del[i]) System.out.printf("%10d",i);
    }
  }
}

Line Number	Algorithm Step (Flowchart)	Description
1	-	Imports the Scanner class for input handling.
2	1 (START)	Class declaration: public class Sieve.
3	-	Method declaration: public static void main(String[] args).
4	-	Declaration of integer variables n, i, j.
5	-	Initialization of the Scanner object named key.
6	-	Writes the prompt "n = " to the console.
7	2 (Read n)	Reads the integer value for n from the user input.
8	3 (n < 2), 4 (Write "bad n")	Checks the condition n < 2 and writes the error message if true.
9	-	Opens the else block (executed if n > 2).
10	-	Declaration and initialization of the boolean array del (size n+1).
11	5 (i := 2), 6 (del[i] := false, i := i+1), 7 (i < n)	Initializes the del array elements from index 2 up to n to false.
12	8 (i := 2) - Initial value is set here	Initializes the control variable i to 1 before the main loop.
13	-	Opens the do loop block.
14	13 (i := i+1), 18 (i := i+1)	Increments i by 1.
15	9 (del[i] == false)	Checks if the number i is not marked as deleted (if(!del[i])).
16	10 (j := i * i)	Initializes j to the square of i (i * i).
17	11 (j < n)	Condition for the inner while loop.
18	12 (del[j] = true)	Marks the current multiple j as deleted/not prime.
19	12 (j := j+i)	Moves to the next multiple of i.
20	-	Closing brace for the while loop.
21	-	Closing brace for the if(!del[i]) block.
22	14 (i^2 < n)	Condition for the outer do-while loop.
23	15 (i := 2), 16 (del[i] == false), 17 (Write: i), 19 (i > n)	for loop: Iterates from i=2 to n to check for and print undeleted (prime) numbers.
24	-	Closing brace for the else block.
25	-	Closing brace for the main method.
26	20 (STOP)	Closing brace for the class Sieve.