You declared space for the array but you still need to declare space for each element in the array. Also, remember that arrays are zero based. That means the first element in the array is [0] and the last is, in your case, [3]. Something like:
public class PbilMain {
public static void main(String[] args) {
Product p[] = new Product[4];
for( int i = 0; i < p.length; i++ )
p[i] = new Product();
p[0].description = "Another trial";
p[1].description = "Yet another trial";
p[2].description = "";
p[3].description = "";
}
}
Greetings.
Daniel