Diamond with loops FAROOQ

import java.util.;
public class day4{
public static void diamond(int n){
//first half
for(int i=1; i<=n; i++)
{
System.out.println("");
//spaces
for(int j=1; j<=n-i; j++)
{
System.out.print(" ");
}
//stars
for(int j=1; j<=(2i)-1; j++)
{
System.out.print("");
}
}
//second half
for(int i=n; i>=1; i--)
{
System.out.println("");
for(int j=1; j<=n-i; j++){
System.out.print(" ");
}
for(int j=1; j<=(2i)-1; j++){
System.out.print("*");
}
}
}

public static void main(String[] args){
    Scanner sf=new Scanner(System.in);
   System.out.println("Enter rows for Diamond");
    int row=sf.nextInt();
    diamond(row);
}

}