access array[i] outside of a method context; not possible?

[gakushya]

This code compiles without error:

public class hello {
 public static void main(String[] args){
   int[] vector = new int[10];
   vector[0]=3;
 }
}

Whereas this code does not compile and generates several errors:

public class hello {
 int[] vector = new int[10];
 vector[0]=3;
 public static void main(String[] args){
 }
}

The errors i get are just like this one:

>./hello.java:3: error: ']' expected
>vector[0]=3;
>       ^

So i feel tempted to conclude that an expression of the form array[i] outside of any method context is illegal?