Fibnocci series easiest way...

public static void main(String[] args) {
  int f = 0;
  int g = 1;

  for(int i = 1; i <= 10; i++)
  {
    System.out.print(f + " ");
    f = f + g;
    g = f - g;
  } 

  System.out.println();
}

Easiest way to reverse string in java and check for palindrome...

class RevString
{
    static String reverse(String str) {
       char[] c = str.toCharArray();
       char[] r = new char[c.length];
       int end = c.length - 1;
    
        for (int n = 0; n <= end; n++) {
           r[n] = c[end - n];
            }
           return new String(r);
        }

 bool isPalindrome(string str) {
  int end= str.length();
  for (int i=0;i<(end/ 2)+ 1;++i) {   
      if (str.charAt(i) != str.charAt(end- i - 1)) { 
         return false;
     }
  }

  return true;
}
 public static void main (String[] args)
 {
  System.out.println(RevString.reverse("hello"));
System.out.println(RevString.isPalindrome("liril"));
 }
}