Can you help me with this code

Question

hi am new to java so please bare with me , so in this code as you can see i comment some lines of code the one i comment works when i compile it , but why the one with fields does not ? can you please explain this to me
public class Demo3
               public static int a = 5;
               public static int b = 6;
               public static int c = a+b;
               public static int d = b-a;
               a*=5;
     public static void main (String [] args)
          /*int a = 5;
          int b = 6;
          int c = a+b;
          int d = b-a;
          a*=5;
          System.out.println (a);
          System.out.println (b);
          System.out.println (c);
          System.out.println (d);
}

Answer 1

>
public class Demo3
               public static int a = 5;
               public static int b = 6;
               public static int c = a+b;
               public static int d = b-a;
               a*=5;This is not possible. write this statement in a function.
or
in a static block like
static  {
      a*=5;
}>
     public static void main (String [] args)
          /*int a = 5;
          int b = 6;
          int c = a+b;
          int d = b-a;
          a*=5;
          System.out.println (a);
          System.out.println (b);
          System.out.println (c);
          System.out.println (d);