Protected - visibility issue????

Question

Hi,
i have the following classes with the following methods:
public abstract class JRBaseFiller
public JasperPrint fill(Map parameterValues, Connection conn)
throws JRException
protected JasperPrint fill(Map parameterValues, JRDataSource ds)
throws JRException
fillReport();
protected abstract void fillReport() throws JRException;
public class JRVerticalFiller extends JRBaseFiller
protected synchronized void fillReport() throws JRException
public class JRVerticalFillerStreaming extends JRVerticalFiller
protected synchronized void fillReport() throws JRException
In my coding, i create a new instance of JRVerticalFillerStreaming as below :
Map parameter,Connection con
JRVerticalFillerStreaming filler = new JRVerticalFillerStreaming();
filler.fill(parameters, con);
And it works fine....
However, changing the Connection type to JRDataSource type
Map parameter, JRDataSource con
JRVerticalFillerStreaming filler = new JRVerticalFillerStreaming();
filler.fill(parameters, con);
results in:
Unhandled event loop exception
Reason:
Unresolved compilation problem:
     The method fill(Map, JRDataSource) from the type JRBaseFiller is not visible
I know that the method fill is of type protected but isn't protected means : Is available to all classes in the same package and also available to all subclasses of the class that owns the protected feature.This access is provided even to subclasses that reside in a different package from the class that owns the protected feature.
In my case, JRVerticalFillerStreaming is a sub sub class of JRBaseFiller.. why it is not visible then? or is it caused by other reasons?
Please advice..
cheers,
ctbozu

Answer 1

>
I know that the method fill is of type protected but
isn't protected means : Is available to all classes
in the same package and also available to all
subclasses of the class that owns the protected
feature.This access is provided even to subclasses
that reside in a different package from the class
that owns the protected feature.
In my case, JRVerticalFillerStreaming is a sub sub
class of JRBaseFiller.. why it is not visible then?
or is it caused by other reasons?
Please advice..
cheers,
ctbozuIt all depends on where you instantiate the objects. B4 we go into an example, pls keep the folln things in mind.
Imagine that you have classes A, B, and C are in three separate packages,
Let C be the class in which a protected member m is declared. Access is permitted only within the body of a subclass S of C.
package com.my;
public class BaseTest
    protected void show(){}
//and then we have in a diff pkg
package com.my.child;
import com.my.BaseTest;
public class ExtendTest extends BaseTest
    public static void main(String args[])
        ExtendTest t = new ExtendTest();       
        t.show(); //this is ok since we r in the base class method and protected is visible
        BaseTest t1 = t;
        //t1.show(); not visible cannot do this
if the main method where we instantiate the objects is in a different Class i.e outside the base class,
package com.my.child;
import com.my.BaseTest;
public class Main
    public static void main(String args[])
        ExtendTest t = new ExtendTest();
        t.showMe();
        //t.show(); not visible outside ExtendTest, cannot do this
        BaseTest t1 = t;
        //t1.show(); not visible cannot do this
}The rule for protected method access is a little bit odd when you first hear it. Look at JLS 6.6.2.1 or go thru this resource http://java.sun.com/docs/books/jls/second_edition/html/names.doc.html#62587
tx,
ram.