Access Class in Default Package

Make long story short, I have to have some class in the "(default package)", related to JNI, and I will need to pass data back and forth from and to these classes from some packaged classes. I am using Java 1.4. As I know since Java 1.4, it's not possible to access classes in default package from packaged classes directly. Is there a work around? please help...

I DON'T have the C/C++ codeSo you have to do with the "old" classes in the default package.
Then use jschell's suggestion to devise proxying code that allow bridging between the packages.
since Java 1.4, I can't call the java class in the default package from packaged class any moreIf I understand jschell's post, this restriction is enforced by the Java compiler , not by the Java interpreter (JVM). Indeed this is specified in the JLS (Java Language Specifications, http://java.sun.com/docs/books/jls/third_edition/html/packages.html#7.5), not the JVM specifications (I have not verified that latter point).
So if you get an older JDK (before 1.4 they would accept the construct), you can try writing proxy classes within a named package, proxying to the old classes in the unnamed package. Once they are compiled, and jarred together for convenience, you can switch back to the current compiler (let's says 1.6) to compile the rest of your application classes, which only use the classes in the named package, using the jar as a library.
When executing the program, the JVM will execute everything without complaining, since it supports execution of compiled code that has been compiled with former versions.

Similar Messages

Implemenet/Extend interface/class in default package

Filename: DeaultInterface.java
public interface DefaultInterface {
// Abstract Methods...
Filename: ConcreteClass.java
package com.company;
import DefaultInterface;
public class ConcreteClass implements DefaultInterface {
// Implementation of Abstract Methods...
}When I compile above java code it gives error "cannot find symbol. symbol: class DefaultInterface".
Can anyone explain why can't we implement the interface/extend the class in default package(no package)?
Edited by: 974531 on Dec 2, 2012 11:07 PM

>
When I compile above java code it gives error "cannot find symbol. symbol: class DefaultInterface".
Can anyone explain why can't we implement the interface/extend the class in default package(no package)?
>
You CAN implement the interface defined in the default package.
What you CANNOT do is import it. And that is because the Java Language Specification specifies that named types can only be referenced by their simple name if they are imported and must otherwise be referenced by their fully qualified name.
See the 7.5 Import Declarations in the Java Language Specification - http://docs.oracle.com/javase/specs/jls/se7/html/jls-7.html
>
An import declaration allows a named type or a static member to be referred to by a simple name (§6.2) that consists of a single identifier.
Without the use of an appropriate import declaration, the only way to refer to a type declared in another package, or a static member of another type, is to use a fully qualified name (§6.7).
A type in an unnamed package (§7.4.2) has no canonical name, so the requirement for a canonical name in every kind of import declaration implies that (a) types in an unnamed package cannot be imported, and (b) static members of types in an unnamed package cannot be imported. As such, §7.5.1, §7.5.2, §7.5.3, and §7.5.4 all require a compile-time error on any attempt to import a type (or static member thereof) in an unnamed package.
>
So you can't reference that type by importing it because you can't import a type that doesn't have a canonical nmae. And you can't just use the simple name because, as the first statement above says you have to import it to use the simple name.
When you use the simple name of that type without an import the simple name would refer to a class IN your 'com.company' named package.

Trying to page import directive in a JSP access a class in default package

I am trying to import a class the is in my default package directory for Tomcat 4.1.18 (context-root\web-inf\classes\*.java). I am getting the following error
This is error using Tomcat 4.1.18
org.apache.jasper.JasperException:Unable to compile class for JSP
C:\Program Files\Tomcat4.1\work\Standalone\localhost\csc297\HTML\SearchByName_jsp.java:9: '.' expected
import Product;
C:\Program Files\Tomcat4.1\work\Standalone\localhost\csc297\HTML\SearchByName_jsp.java:10: '.' expected
import Category;
This is error using Tomcat 4.0.6
org.apache.jasper.JasperException: Unable to compile class for JSPNote: sun.tools.javac.Main has been deprecated.
C:\forte4j\tomcat401\work\localhost\C_3A_5Cforte4j_5Ctomcat401_5Cwebapps_5Ccsc297\HTML\SearchByName$jsp.java:5: Class Product not found in import.
import Product;
^
C:\forte4j\tomcat401\work\localhost\C_3A_5Cforte4j_5Ctomcat401_5Cwebapps_5Ccsc297\HTML\SearchByName$jsp.java:6: Class Category not found in import.
import Category;
Here is snippet of code from my JSP:
<%@ page import= "java.util.*"%>
<%@ page import= "java.text.DecimalFormat"%>
<%@ page import="Product"%>
<%@ page import="Category"%>
Remember these classes are in my default package of my context-root
Any ideas would greatly appreciated

Weird error. Never seen this one before.
Try packaging your classes eg:package myClasses;and import them:<%@page import="myClasses.*"%>Should fix the problem.
Anthony

Importing class from default package of a JAR

I want to create objects of a class contained in a JAR. The JAR has many classes in numerous packages, however the class that I want to use is in the default package. I'm using eclipse and have added the JAR to the build path, but eclipse complains that the class name cannot be resolved. Is there some way to specify an import statement to look in the default package of a particular JAR? Any advice is appreciated.

jg2009 wrote:
I was under the impression that classes without a defined package were technically considered to be part of the so-called default package. But, in answer to your question, yes this class does not appear to part of any package.
Just to provide so additional information, the class that I want to instantiate is an Applet, so it is designed to be called from an html object tag, and have access to all of the other classes in its JAR. There is a system that provides access to underlying data via the following components: html form <-> javascript <-> applet <-> serverlets <-> data
I want to automate certain data operations, but the only way to access the underlying data is via the applet. Am I out of luck, or is there some way that I can instantiate the applet?All jverd said is right, assuming it is your code and you can change it: basically move everything to a package. But I think your problem is that the jar is a 3rd party jar and you cannot change it. If this is the case, you can use the 'default package' (the terminology is correct) by having your own class(es) in the default package or by using reflection (last time I tried reflection would work). Both are rather bad solutions, but if you really, really want...
Note: Java actively discourages the use of the 'default package' and more so recently, this is why I am not even sure that reflection would still work.

Importing classes from default package

hey all,
I've just started a new job, and find myself having to use a library that is written in the default package. At the moment, this is forcing me to put my classes in the default package whenever I want to use this library.
using a line like:
import RowBean;
I get the following compiler error:
    [javac] C:\work\coyote\src\java\com\sok\coyote\Grievance\GrievanceActionServlet.java:8: '.' expected
    [javac] import RowBean;I've tried classic,modern and jikes - all with the same error.
Eclipse seems to compile this happily, but I've been unable to find what it does to compile it.
any ideas?
cheers
dim

This works for me in 1.3.1_07
DefaultPackage
public class UseMe
     public static final String test = "Yes";
}Package = fun
package fun;
import UseMe;
public class Fun
     public static void main( String[] args )
          System.out.println( UseMe.test );
}

Weird Can not access class from outside package problem

Hi, I have this problem and it seems the error message is very clear what the problem is but I did make the GeneralTestResult class PUBLIC already. What could be wrong? I did search for it but this is too general and didn't find any solution. Anyone can point out the problem? TIA.
public abstract class GeneralTestResult
public static int FAILING_THRESHOLE = 25;
public abstract String getTestName();
public abstract boolean isPassed();
public abstract int getLeftEyeResult();
public abstract int getRightEyeResult();
public abstract Calendar getTestDate();
// in a different file
package VisionSaver.Tests.TestResults;
import java.util.*;
public class AcuityORContrastTestResult extends GeneralTestResult
private String m_testName;
private int m_leftEyeVision, m_rightEyeVision;
private Calendar m_testDate;
// in a different file
package VisionSaver.Tests;
import VisionSaver.Tests.TestResults.*;
public class Acuity extends VirtualKeyboard implements ActionListener, Runnable, WindowListener
AcuityORContrastTestResult r = new AcuityORContrastTestResult(...);
}The compiling error is:
"Acuity.java": GeneralTestResult() in VisionSaver.Tests.TestResults.GeneralTestResult is not defined in a public class or interface; cannot be accessed from outside package at line 529, column 40

The GeneralTestResult class is a packaged class. Sorry, when I cut and paste, I didn't copy everything. So here is the complete GeneralTestResult file:
package VisionSaver.Tests.TestResults;
import java.util.*;
public abstract class GeneralTestResult
public static int FAILING_THRESHOLE = 25;
public abstract String getTestName();
public abstract boolean isPassed();
public abstract int getLeftEyeResult();
public abstract int getRightEyeResult();
public abstract Calendar getTestDate();
}From the compiler's message, it seems like the import is OK. It just won't allow me to access non-public class but my classes here are declared public. Any other ideas? TIA

Problem Accessing Class in my package from jsp file

Hi,
I am using Apache tomcat server and i have made package which contains a class for database connection. I have imported this package in my jsp file but when i run the jsp tomcat gives the class not found exception. i have placed the jsp file in /webapps/my_project/ folder and the package in the /webapps/my_project/WEB-INF/classes/ folder.
Still its not working.
Please help me out!!!!!!!!

hi,
Thanks for ur reply. You have guessed it right, i dont have a .jar file its a .class file in a package subfolder. I have tried out ur suggestion but it didnt work. The following error i shown when i run it.
org.apache.jasper.JasperException: Unable to compile class for JSPNote: sun.tools.javac.Main has been deprecated.
C:\Apache Tomcat 4.0\work\localhost\_\College\test$jsp.java:4: Package college_lib not found in import.
import college_lib.*;
^
1 error, 1 warning
Here, College_lib is the package name which contains the class my class file
Is there any problem with my Apache Tomcat4.0 or any other thing.
Message was edited by:
Despo

Access default package

Is it posible to access a class in default package from the some package called
MyPackage
if its not possible means why?
thanx in advance

why its not allowing to access?, is there practical
problem to find the current folder while loading the
classI guess it's to discourage from usage of the default package.
You can't import the default package. It's not something that would be hard to implement. Classes in the default package were actually accessible in the first versions of Java.
Kaj

Accessing Class not in the package by the Class in the Package.

Hi All,
I am using window my java application are located at
c:\javaProg\completeReferance\......
my Class path is set to c:\....
Iexecute java application using
java javaProg.completeReferance.MyProgramThe problem is when I wanted to use some other class which is not in any package I get the following error.(say class Car).
C:\Users\pravin>javac c:\javaProg\completeReferance\SystemDemo2.java
c:\javaProg\completeReferance\SystemDemo2.java:7: cannot find symbol
symbol : class Car
location: class javaProg.completeReferance.SystemDemo2
                Car object = new Car();
                ^
c:\javaProg\completeReferance\SystemDemo2.java:7: cannot find symbol
symbol : class Car
location: class javaProg.completeReferance.SystemDemo2
                Car object = new Car();
                                 ^
2 errorsThis is my program ...package javaProg.completeReferance;
public class SystemDemo2
     public static void main(String [] args)
          Car object = new Car();
}Where should it place the class file for Car class.Can some one explains who to make the class from one package compitable with classes in default package or any other package.I hope this problem may be faced by lots of newbies.
Appreciate your concern!
Message was edited by:
confused_in_java

There's nothing wrong with it per se... but it has a
number of pitfalls. Basically it's a hell of a lot
more likely to go wring at runtime than the good ole
"just put the class in a package and import the
sucker properly" solution.Alredy implemented this now.
That's what makes me shudder to see it in the
(forgive me) shakey hands of a newbie... it's a bit
like watching a tree year old trying to open a box of
matches... if you've got any brains you push the
rubber ducky in his hands and quietly secrete the
matches in the cupboard above the fridge... and get
yourself another beer whilste you're there.
Christians don't drink on Sunday. So there's more for
me.Thanks I wil remember this.
I am about to put a new Thread I thought insted so putting a new thread I will ask it here.
This Question is a bit wiered so please excuse me if you think this is foolish.
I was just wonder that if we can put our package, which include classes offcourse at some web location, then this will be available to us from anywhere and can be shared all accross.
So I am tring to dumb the package in a jarfile and place it at my webspace http://pravin.biz.ly/ how ever somehow i have problem doing it can any one help.
Regards!!
Pravin Dubey.
Message was edited by:
confused_in_java

Class name and package name clashing

When i have a class and a package with the same name, I cannot access classes in the package. For example I have 3 classes and 1 package as below
- Test.java
- PackageName.java
+ PackageName // this is a directory
- MyClass.java
Below are the codes of .java files
Test.java
=======
public class Test { PackageName.MyClass a = new PackageName.MyClass ();}
PackageName.java
===============
public class PackageName{ }
MyClass.java
==========
package PackageName; public class MyClass { }
I can compile PackageName.java and MyClass.java but not Test.java. It says
cannot resolve symbol
symbol : class MyClass
location: class PackageName
PackageName.MyClass a = new PackageName.MyClass ();
But if I remove the PackageName.java, I can compile Test.java perfectly. I think when I use PackageName.MyClass, java thinks that I try to access an inner class MyClass of PackageName class, and that does not exists. Is there any way to solve this ambiguation, other than making the package name and class name different? Thank you very much.

This works fine: just add an import to Test.java.
import PackageName.MyClass;
public class Test
    public static void main(String [] args)
        MyClass a = new MyClass();
public class PackageName {}
package PackageName;
public class MyClass {}It's a pretty wacky, useless example, but it works.
Plus I thought inner classes would have a dollar sign in their .class file names. When I compile this:
public class OuterClass
    public static void main(String [] args)
        OuterClass outer = new OuterClass();
        System.out.println(outer);
    public String toString() { return "I'm an OuterClass"; }
    class InnerClass
        public String toString() { return "I'm an InnerClass"; }
}I see two .class files: OuterClass.class and OuterClass$InnerClass.class
Why make up examples like this? It's hard enough writing code, and it's easy to disambiguate for the compiler.

Not able to access default package classes in own package

I created a class called Constant.java in default package(no package ).
I have Connection.java in util package.
I am trying to use the Constant.java in my Connection.java like below..
public class Constant
public static final String NEW = "01";
package util;
import Constant;
public class Connection
I am unable to compile the class Connection. My question here is Won't I able to access default package in my util package.. ?

java_guy04 wrote:
Djaunl , I understand.
but, Will I able to access default package in my util package.. ? is this correct.No, you won't be able to use classes out of the "default" package.
Because, AFAIK, if you use a classname that you haven't imported, Java automatically attempts to locate this class in the same package as the current class. It does not check the "default" package (unless that is also the current package), and since the "default" package does not have a package name, you can't import those classes either.

Default/package/none access modifier

Hi,
I was hoping for some discussion on the default/package/none access modifier. It's always really bugged me that we have public, private, protected, and then "none", while it seems to me that it would be less confusing, and more consistent to use the keyword "package", or maybe even "default".
Then, source code would look like
public class MyClass{
    public int getValue() {}
    private void setValue() {}
    protected void someMethod() {}
    package int justForPackage() {}
}I know this concept has come up before, but the books I've read which mention this topic haven't offered any actaul justification/explanation for why there isn't some keyword.
Anyway, are there any insights as to why java is this way, and any reasons why java should or shouldn't be changed to include the package access modifier.

A good example is within a tightly grouped package (usually should be this way) you may have some cooperative classes that access methods.
// one .java file
public class SomeHelper {
   private void method() {
     new ClassForUsers().accessHiddenLogic();
// next .java file in same package
public ClassForUsers {
    /* default-access */ void accessHiddenLogic() {
}But, you may want to allow users to subclass your ClassForUsers, without giving them access to the hidden logic method directly:
// another .java file in a different package
public class UsersSubclass extends ClassForUsers {
    public void userMethod() {
        // can't do this
        accessHiddenLogic();
}This could be for either business logic or security reasons. So, package level access can be very useful. However, I've seen that in practice it is avoided because it isn't obvious what is going on.

Why does protected access also allow access from classes in same package

Having been asked the question and found myself unable to answer it, I wonder if anyone can explain the reasoning why protected access implies the default access as well?

Sure:
---------- class A ------
package pkg;
public class A
protected static int _a;
private int _i;
public A() { _i = _a++; }
public String toString() { return "instance "+_i; }
--------- class B ------
package pkg;
public class B
public B() { A._a = 27; }
--------- class C -----
public class C extends pkg.A
-------- class main ----
public class main
public static void main(String[] args)
pkg.B b1 = new pkg.B();
pkg.A a1 = new pkg.A();
pkg.B b2 = new pkg.B();
C c1 = new C();
System.out.println("a1 is "+a1);
System.out.println("c1 is "+c1);
The above classes are legal and compile and when
run, the output is:
a1 is instance 27
c1 is instance 27
(Please note, this is just an example of what is allowed and why I'm curious as to the advantages of this permitted behaviour, NOT what I would ever write!)

Accessing default package in own package ****

I created a class called Constant.java in default package(no package ).
I have Connection.java in util package.
I am trying to use the Constant.java in my Connection.java like below..
public class Constant
public static final String NEW = "01";
package util;
import Constant;
public class Connection
I am unable to compile the class Connection. My question here is Won't I able to access default package in my util package.. ?

You indeed can't import from the default package.

Default access class

I tried searching for this but couldn't find it. If you have a package-access class, are there any special rules on access modifiers allowable for variables and methods?
Thanks.

No.Good answer.
http://java.sun.com/docs/books/tutorial/java/java
OO/accesscontrol.html
http://java.sun.com/docs/books/tutorial/java/java
OO/classdecl.html
http://java.sun.com/docs/books/tutorial/java/java
OO/index.html
http://java.sun.com/docs/books/jls/third_edition/
html/j3TOC.html
Offset your good answer with these useless links.
So, why is there no restriction? If you have a default-access classes but public (or protected?) members, wouldn't they still not be accessible for that class? Though it could just be another "simply memorize it" rule, are there any reasons you might think of for why it's done like that?

Access Class in Default Package

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