string index out of bound exception

Question

import java.util.*;
import java.lang.*;
import java.io.*;

public class pali
{

public static void main (String[] args)
{
Scanner sc= new Scanner(System.in);
int test_cases= sc.nextInt();
for(int i= 0 ; i< test_cases;i++)
{
int len= sc.nextInt();
String str=sc.nextLine();
String p = "";
for(int j=0;j<len;j++)
p= str.charAt(j)+p;
System.out.println("p");
if(p.equals(str))
System.out.println("Yes");
else
System.out.println("No");
}

}
}

/* Exception in thread "main"// java.util.NoSuchElementException
at java.util.Scanner.throwFor(Scanner.java:862)
at java.util.Scanner.next(Scanner.java:1485)
at java.util.Scanner.nextInt(Scanner.java:2117)
at java.util.Scanner.nextInt(Scanner.java:2076)
at gfg_pali.main(File.java:14) */

Answer 1

int len = str. length();

Answer 2

Instead of relying on your user to input the length of the string, it's probably best to get the length programmatically.