Accessing Variables - What Is The Final Value Of Counter

While reading head first java i encountered a problem(Pg. 90 chapter 4 - mixed messages).

Suppose in a class(say A) outside main() a counter variable is declared and initialized to 0.

In main() declared the array of objects of the class A.

Consider a while loop in which we increment the counter as follows:

public class A{
int counter = 0;
public static void main(String[] args){
A[] arr = new A[20];
int x = 0;
while(x<4){
arr[x] = new A(); //arr[] is array object
arr[x].counter += 1;
x++;
}
}
};

what is the final value of counter ? will it be the same for all array objects.