Using packages

[prfalco]

Hello there!
I have someting that seams trivial, but it's a pain in the neck for me.
I have several related classes that I want to organize in a package.
So, in every class, in the top I write: package whatever;
I have a folder named whatever where I put all my classes, then compile like this: javac -classpath c:\whatever c:\whatever\class1.java
Then I setup my environment variable CLASSPATH and tested like this: C:\>set classpath and I get my C:\whatever, so seems to be ok.
But when I try to 'use' one of the classes in my whatever package I get an error like "no such a package"
Somebody help me please!

[tim]

Welcome to the forums prfalco

I made an example for you. It is a package that you can run and use from text files and batch files. I just self studied this topic, so I can explain this in detail, if that is what you want. The example has been attached to this reply. It was created in Windows and it is a ".zip" file. Unzip it in the root of your C drive and run the batch file using "Command Prompt". Do not double click on it, because if there is a problem it will disappear before you can read it.

I hope this helped.

[prfalco]

Quote:

Originally Posted by tim

Welcome to the forums prfalco

I made an example for you. It is a package that you can run and use from text files and batch files. I just self studied this topic, so I can explain this in detail, if that is what you want. The example has been attached to this reply. It was created in Windows and it is a ".zip" file. Unzip it in the root of your C drive and run the batch file using "Command Prompt". Do not double click on it, because if there is a problem it will disappear before you can read it.

I hope this helped.

I have a class as the one that follows on a folder called person :

package person;

public class name{

private String name_person= "pablo";

public String get_name(){
return name_person;
}

}

I compile it using: javac name.java with success.

Then I have this other class which is supposed to use the other one just importing it :

import person.*;

public class Letscheck {

public static void main(String[] args) {
name n = new name();
System.out.println(n.get_name());
}
}

I compile like this: javac c:\person\Letscheck.java and guess what? I get my dear error: package person does not exist.
I set up my classpath environment variable in windows XP to point to .;c:\person.

Gee.....

Thanks for your help.

[tim]

Hello prfalco

I know this can be frustrating, but please try to understand that if you can do this, then you can use Java fundamentally without an IDE to spoil you.

I am assuming that your Java compiler and interpreter is working. Lets make sure of the structure:
This is your Letscheck class with the main() method. Currently it is part of the default package:

Code:

import person.*;
public class Letscheck {

	public static void main(String[] args) {
		name n = new name();
		System.out.println(n.get_name());
	}
}

This file, called Letscheck.java, is stored as:

Code:

c:\java\Letscheck.java

Next, you have your name class that is part of your person package:

Code:

package person;
public class name{
	private String name_person= "pablo";
	public String get_name(){
		return name_person;
	}
	// Added a constructor for you
	public name(){}
}

this file, called, name.java, is saved as:

Code:

C:\java\person\name.java

Now open command prompt and type

Code:

cd c:\java\person\

To use javac we do not need a CLASSPATH. Type the following:

Code:

javac *.java

This will compile all your java source code in the "c:\java\person\" directory. Now, we do the same for "c:\java\" to compile the file with your main() method:

Code:

cd c:\java\
javac *.java

Now you should have the files:

Code:

c:\java\person\name.class
c:\java\Letscheck.cass

To run a Java program with the Java interpreter, it needs a CLASSPATH. To set this, use the command prompt before you use the "java" program. Type this into the command prompt:

Code:

SET CLASSPATH=c:\java\

Note that all my directories ends with a back slash. Now, to run your program type:

Code:

java Letscheck

Note that I did not add the ".class" extension. The program should output:

Code:

pablo

That's all that there is to it. You can do all this quickly by writing a batch file. (.bat)

I really hope this helped you.

[prfalco]

Quote:

Originally Posted by tim

Hello prfalco

I know this can be frustrating, but please try to understand that if you can do this, then you can use Java fundamentally without an IDE to spoil you.

I am assuming that your Java compiler and interpreter is working. Lets make sure of the structure:
This is your Letscheck class with the main() method. Currently it is part of the default package:

Code:

import person.*;
public class Letscheck {

	public static void main(String[] args) {
		name n = new name();
		System.out.println(n.get_name());
	}
}

This file, called Letscheck.java, is stored as:

Code:

c:\java\Letscheck.java

Next, you have your name class that is part of your person package:

Code:

package person;
public class name{
	private String name_person= "pablo";
	public String get_name(){
		return name_person;
	}
	// Added a constructor for you
	public name(){}
}

this file, called, name.java, is saved as:

Code:

C:\java\person\name.java

Now open command prompt and type

Code:

cd c:\java\person\

To use javac we do not need a CLASSPATH. Type the following:

Code:

javac *.java

This will compile all your java source code in the "c:\java\person\" directory. Now, we do the same for "c:\java\" to compile the file with your main() method:

Code:

cd c:\java\
javac *.java

Now you should have the files:

Code:

c:\java\person\name.class
c:\java\Letscheck.cass

To run a Java program with the Java interpreter, it needs a CLASSPATH. To set this, use the command prompt before you use the "java" program. Type this into the command prompt:

Code:

SET CLASSPATH=c:\java\

Note that all my directories ends with a back slash. Now, to run your program type:

Code:

java Letscheck

Note that I did not add the ".class" extension. The program should output:

Code:

pablo

That's all that there is to it. You can do all this quickly by writing a batch file. (.bat)

I really hope this helped you.

Finally !!! I've got it. I've printed it for future reference, and of course, study it. Many many thanks.

[tim]

I'm very glad that it worked. It took me some time and effort to create that post.