Class Visibility of Protected Members between Packages

Hi,
I'm developing a system that consists of package A, which in turn contains packages B and C. My database access class is in a package by itself (package A.B) and I want anyone who uses it to provide a username and password. In order to do this, my system has a class called Config.java which resides in package A. When Config.java is instantiated, it will read the contents of some configuration xml file on the system and set protected variables for the username and password.
My problem is the following:
1. Config.java is not visible to any other classes in other packages unless it is public
2. If Config.java is made public, then anyone can inherit from it and have access to its protected members.
3. The other classes (in package A.C) must have access to the username and password in order to supply it to the database access class.
How can I get around this?
Thanks,
Ama

What is your concern, what someone will hack your
database by deriving
from Config?
Is that a reasonable fear -- couldn't they just look
in the XML file you mention?Well, hopefully that xml wont be so accessible, I'm thinking it will be necessary in case the user wants to modify any database settings through the application configuration screens.
I guess what my question is really, is where would a large application that needs to access a database usually store the username and password information? Surely it cant be hardcoded in the application somewhere? What if the user wants to change the connection info?

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Accessing protected members

Hi,
Can one of you please clarify the following doubt.
CLASS A
package com;
public class A {
     protected String name = "JAVA";
     protected void m1(){
          System.out.println("m1");
CLASS B
package com.abc;
import com.A;
public class B extends A {
     public static void main( String [] args ) {
          B b = new B();
          b.mt();
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CLASS C
package com.abc.xyz;
import com.abc.B;
public class C extends B {
     public static void main( String [] args ) {
          C c = new C();
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     public void mttt() {
          System.out.println("name --> " + name);
          m1();
====================================
Now in one of the books I read that a protected member of parent class (say A) is accesible thru inheritance in a subclass in different package (say B). Perfect!
But also says that another class (say C) inheriting the above subclass either in a the same or different package cannot access the protected members of the parent class (A).
Surprisingly above code compiles and runs perfectly on my machine. Checked the JDK version and is 1.3 but the books is for 1.4
Can some one please clarify which is correct.
Thanks in Advance.

I was expecting a compilation error (in class C as it cannot access the protected members of class A) according to the book I read. But I observed that it is compiling and running perfectly.
Following the code again for clarity:
CLASS A
package com;
public class A {
     protected String name = "JAVA";
     protected void m1(){
          System.out.println("m1");
CLASS B
package com.abc;
import com.A;
public class B extends A {
     public static void main( String [] args ) {
          B b = new B();
          b.mt();
     public void mt() {
          System.out.println("name --> " + name);
          m1();
CLASS C
package com.abc.xyz;
import com.abc.B;
public class C extends B {
     public static void main( String [] args ) {
          C c = new C();
          c.mttt();
     public void mttt() {
          System.out.println("name --> " + name);
          m1();
}Message was edited by:
talk2key

What is the diffrence between package javax.sql and java.sql

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Hi,
What is the diffrence between package javax.sql and java.sql?The JDBC 2.0 & above API is comprised of two packages:
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2.The javax.sql package.
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Gayam.Srinivasa Reddy
Developer Technical Support
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http://www.sun.com/developers/support/

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How can I import that class?
Best wishes to all ...
Heiko

> I have the following problem:
A class A is not in a package. In another class B,
which is in a package (let's say package X) I want to
use the class A. Without importing the class A, I get
the error "Cannot resolve symbol".
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EXP="true"
CAP="true"
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packageaid="0x01:0x01:0x01:0x01:0x01:0x01:0x01:0x01:0x02:0x00"
majorminorversion="1.0"
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[echo] Generation of the CAP,JCA and EXP files...
[convert] Java Card Ant Tasks, Version 1.0
[convert] Copyright 2005 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms.
[convert] Note: Usage of Java Card Ant Tasks is optional. Java Card Ant Tasks are not supported by Sun Microsystems, Inc.
[convert] Java Card 2.2.2 Class File Converter, Version 1.3
[convert] Copyright 2005 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms.
[convert] parsing /home/ehoudart/app-manager/VersionZero/src/testUn/classes/testUn/PorteAppUn.class
[convert] converting testUn.PorteAppUn
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<property name="target.classes" location="${basedir}/target/classes" />
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<property name="javacard.libs" location="${basedir}/lib" />

<property name="javacard.ant-task" location="${basedir}/lib" />

<property name="javacard.export" location="${basedir}/src/main/export" />
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<taskdef name="verifyrevision" classname="com.sun.javacard.ant.tasks.VerifyRevTask" classpathref="classpath" />
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</target>
<target name="all" depends="clean, convert" />
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Calling a object of class from other class's function with in a package

Hello Sir,
I have a package.package have two classes.I want to use object of one class in function of another class of this same package.
Like that:
one.java
package co;
public class one
private String aa="Vijay"; //something like
}main.java:
package co;
import java.util.Stack;
public class main extends Stack
public void show(one obj)
push(obj);
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main oo=new main();
}when I compile main class, Its not compile.
Its give error.can not resolve symbol:
symbol: class one
location: class co.main
public void show(one obj)
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kumar.vijaydahiya wrote:
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c:\Core\co\javac main.javaBut it give error.
Both java classes in co package.Okay, open a command prompt and execute these two commands:
// to compile both classes:
javac -cp c:\Core c:\Core\co\*.java
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java -cp c:\Core co.main

How to call class file from jsp without creating packages

i m using tomcat 5.5
i stored my class file into WEB-INF\Class directory
how to call that class file. from my jsp page.
i got some error.
i used package concept,that works fine.

i m using tomcat 5.5
i stored my class file into WEB-INF\Class directory
how to call that class file. from my jsp page.
i got some error.
i used package concept,that works fine.Then use packages.
As of Java1.4, you can no longer import classes from the default package (no package declared) into classes that are packaged.
All Tomcat classes are in packages, including the compiled JSP.
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Class.forname - Unable to load class if two jars with same package name

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Hello...
I have 2 packages, the first (named "Library") is inttended to use as a library of miscelaneuos functions, all of them, inside one (and the only one) public Class named "MiscFunctions"
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can somebody help me pleasee !!
i will be grateful !...
i' alooone with java...

CALLER.JAVA
package Example;
import library.Funcs;
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The method fIsMember invoked for type Example.Caller with arguments
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public class Funcs {
public boolean fIsMember(ArrayList x, String s) {
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How to reduce protected accessor to package accessor in child class

I have made one abstract class ( say Parent), with 2 abstract methods (am1() & am2()) , with protected accessors. A class extends parent class (say Child). Now Child class need to keep accessors type of protected method as protected, as we cannot reduce the scope. Now as per my design, I need to create many subsclass (say SubClass) of Child class. But I don't want subclass of Child class to have access of method am1() & am2(). SubClass is declared in different package. But as I cannot reduce the accessor type from protected to package, I am not able to restrict the access of am1() & am2() to Child class and SubClass should not able to access am1() & am2().
Do we have some way to design above scenario?
Thanks in advance
Praveen

You can't reduce visibility.
A subclass is supposed to be able to do everything the superclass can. If you'd restrict visibility of certain methods or fields, you break that contract.

Why we cannot reduce protected accessor to package accessor in child class?

Hi,
I have made one abstract class ( say Parent), with 2 abstract methods (am1() & am2()) , with protected accessors. A class extends parent class (say Child). Now Child class need to keep accessors type of protected method as protected, as we cannot reduce the scope. Now as per my design, I need to create many subsclass (say SubClass) of Child class. But I don't want subclass of Child class to have access of method am1() & am2(). SubClass is declared in different package. But as I cannot reduce the accessor type from protected to package, I am not able to restrict the access of am1() & am2() to Child class and SubClass should not able to access am1() & am2().
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Double Post:
http://forum.java.sun.com/thread.jspa?threadID=634969
Triple post actually.
http://forum.java.sun.com/thread.jspa?threadID=634985
http://forum.java.sun.com/thread.jspa?threadID=634969

Visibility of protected

Hi,
I was just thinking - why members marked with protected level visibility
allow other classes in the same package for accessing it ?
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Cheers,
Adrian

Hmmm,
I see what you mean. Perhaps I still can't get rid of C++ out of my mind :/
I must remember that the whole language has been designed on packages basis
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Thanks anyway !
Adrian

Protected members not protected?

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1.4.1_05
public class ComponentModel extends ContainerModel implements IComponentModel{
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As an above poster mentioned, if you scroll up it is described more clearly. I will post it though.
A member (class, interface, field, or method) of a reference (class, interface, or array) type or a constructor of a class type is accessible only if the type is accessible and the member or constructor is declared to permit access:
If the member or constructor is declared public, then access is permitted. All members of interfaces are implicitly public.
Otherwise, if the member or constructor is declared protected, then access is permitted only when one of the following is true:
Access to the member or constructor occurs from within the package containing the class in which the protected member or constructor is declared.
Access is correct as described in ?6.6.2.

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package my.gui;
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And the code for TestJPanel.java
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If you really want to learn Swing, I advise you to put the NetBeans away, and dive into the Sun Swing tutorials where you'll learn to code your Swing by hand. One of the main things that you'll learn -- and likely the thing that is tripping your current code up -- is how to use layout managers in a way that will allow you to flexibly place JPanels and other components where you want them, where they'll resize if need be, and where they'll be visible when you want them to be.
Much luck.

Class Visibility of Protected Members between Packages

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