asked on

Java Package

Hello Experts,

I am a junior Java Developer. Wondering if someone can help me on how to use a package that I created.

For example the code below:

package test;

public class A {
public void Printing("hello");
}

I save this file as A.java and compile it to a class file called A.class

Next, I jar it to test.jar and i set a classpath point to test.jar

Then I create a file called B.java with the following code:

package test;

public class B {
public void main(String args[]){
A a = new A();
a.Printing();
}
}

When I compile this B.java, I encounter this problem:

cannot resolve symbol
symbol : class A
location: class test.B

So, can u tell me how I can compile B program using test package successfully... Your help will be appreciated

dekoay

Mick Barry

You need to ensure that both class A and B are stored in a directory structure matching your package hierarchy. In your case you need to put both in a directory called 'test'.
You also need to ensire your jar file contains matching directory structure.

gandalf94305

You have to compile A.class into a subdirectory test. The jar should contain test/A.class (verify with "jar tvf test.jar").

Compiling B.java, the classpath must contain either the directory holding test/A.class or the jar.

Running B.java you must have in your classpath the directory holding "test/B.class" and "test/A.class", or the directory holding "test/B.class" and the jar containing "test/A.class", or the jar containing "test/B.class" and "test/A.class".

Cheers,
--gandalf.

dekoay

ASKER

Hi Experts,

My source code is as below:
Filename A.java

import java.io.*;
public class A
{
public A()
{
}

public void printing()
{System.out.println("Hello World!");}
}

Filename B.java

import test.*;
public class B
{
public static void main(String[] args)
{
A obj=new A();
obj.printing();

}
}

I compile A.java and manage to jar it as well. I also manage to compile B.java by using the package test.jar.
Unfortunately when I try to execute B, it gave me this error:

NoClassDefFoundError: test/A at B.main(B.java:7)

What is wrong with my code in B.java? Your help will be appreciated.

gandalf94305

How about putting a

package test;

as the first line in each of the two files?

--g.

dekoay

ASKER

Hi Gandalf,

Thanks for the response. I have tried as u mention. But the problem still occur.. Dun know where goes wrong with this simple code. Hope u can show me how to solve it.

Thanks

Dekoay

dekoay

ASKER

Hi Gandalf,

Thanks for the response. I have tried as u mention. But the problem still occur.. Dun know where goes wrong with this simple code. Hope u can show me how to solve it.

Thanks

Dekoay

dekoay

ASKER

Hi Gandalf,

Thanks for the response. I have tried as u mention. But the problem still occur.. Dun know where goes wrong with this simple code. Hope u can show me how to solve it.

Thanks

Dekoay

ASKER CERTIFIED SOLUTION

gandalf94305

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Mick Barry

Place your java files into a 'test' directory as I stated in my original post. And ensure your classpath is set as mentioned.

eg.

If you keep your java files in a directory c:\java, then A.java and B.java should go in the following directories:

c:\java\test\A.java
c:\java\test\B.java

You should include c:\java in your classpath.

To jar them up you should be in the directory c:\java and use the command:

jar cvf test.jar test