Javac cannot find the parent class

[Kok Lum Chan]

Hi all,

I tried to put 2 files (parent and child) into 2 different packages (LearnJava.One & LearnJava.Two) as shown in the attached.

Parent - compiled success.

package LearnJava.One;

public class Parent
{
   public int x = 8;
}

Child - compile with errors

package LearnJava.Two;
import LearnJava.One.Parent;

public class Child extends Parent{

  public static void Main(String[] args)
  { }
}

The error i got is

D:\LearnJava\Two>javac Child.java
Child.java:2: package LearnJava.One does not exist
import LearnJava.One.Parent;
                    ^
Child.java:4: cannot find symbol
symbol: class Parent
public class Child extends Parent{
                           ^
2 errors

I have updated that CLASSPATH to point to the location of the Parent.class but i still unable to figure out why i got the error.

Classpath = .;D:\LearnJava;D:\LearnJava\Two;D:\LearnJava\One;<some other paths>

Appreciate if anyone could assist to highlight my mistake(s).

Thanks.

[marc weber]

koklum chan wrote:...I have updated that CLASSPATH to point to the location of the Parent.class but i still unable to figure out why i got the error.

Classpath = .;D:\LearnJava;D:\LearnJava\Two;D:\LearnJava\One;<some other paths>...

Java is looking for the package, "LearnJava.One." The location of this is simply "D:\", which does not appear to be included in your classpath.

[marc weber]

Note that you could also do this from the command prompt as follows...

D:\LearnJava\Two>javac -cp ../.. Child.java

In this case, your current directory is D:\LearnJava\Two, and you are specifying a classpath (-cp) that is two directories higher (../..), which puts you back at D.

OR you could simply use D as your current directory (which is where these packages reside, so the dot in your classpath should work), and then provide the relative path for compiling Child.java...

D:\>javac LearnJava/Two/Child.java

[Kok Lum Chan]

Hi Marc,

Thank you for your guidance and your recommentation works.

marc weber wrote:

koklum chan wrote:...I have updated that CLASSPATH to point to the location of the Parent.class but i still unable to figure out why i got the error.

Classpath = .;D:\LearnJava;D:\LearnJava\Two;D:\LearnJava\One;<some other paths>...

Java is looking for the package, "LearnJava.One." The location of this is simply "D:\", which does not appear to be included in your classpath.

This is what i do not understand. Why Java cannot locate the parent.class when i am using absolute path (D:\LearnJava\One) in CLASSPATH but specifying D:\ works ?

Is it trying to locate the package (not covered in my classpath) then only the class in the package (covered in the classpath) ?

[Henry Wong]

koklum chan wrote:

This is what i do not understand. Why Java cannot locate the parent.class when i am using absolute path (D:\LearnJava\One) in CLASSPATH but specifying D:\ works ?

Is it trying to locate the package (not covered in my classpath) then only the class in the package (covered in the classpath) ?

The classpath is used to specify the location of the root of the class files -- not the location of the class files. So if you specify the class path as D:\LearnJava\One and you specify the package as LearnJava.One, then it will look for the class file in D:\LearnJava\One\LearnJava\One\Parent.class.

Henry

[Kok Lum Chan]

Hi Henry,

That explains everything. Thank you.