How does this work ?

[sachin jauhari]

Why does the following give compilation error at line 1.
Class B extends Class A which is in a different package.

//in file A.java
package p1;
public class A
{
protected int i = 10;
public int getI() { return i; }
}

//in file B.java
package p2;
import p1.*;
public class B extends p1.A
{
public void process(A a)
{
a.i = a.i*2; // line 1
}
public static void main(String[] args)
{
A a = new B();
B b = new B();
b.process(a);
System.out.println(a.getI());
}
}

[Brijesh Dinkar]

when you are accessing the variable 'i', you are not making use of inheritance, hence the problem.The protected variable 'i' will not be visible to classes outside the pacakge unless you make use of inheritance.
So somethin like this will work-
package p1;
public class A
{
protected int i = 10;
public int getI() { return i; }
}

package p2;
import p1.*;
public class B extends p1.A
{
public void process()
{
i = i*2; // line 1
System.out.println(getI());
}
public static void main(String[] args)
{
new B().process();
}
}

Hope this helps!

Brijesh