Java Aggregation

class Calculate
{  
    int rectangle(int n,int m)
    {  
        return n*m;  
    }  
}  
class A
{
    int rect;
    A(int length,int breadth)
    {   //aggregation
        Calculate ca; 
        ca=new Calculate();  
        rect=ca.rectangle(length,breadth);
        System.out.println("Area of Rectangle: "+rect);
    } 
}
public class Aggregation
{  
    public static void main(String args[])
    {  
        A c=new A(7,9); 
    }  
}