Compile java file with a package using Oracle JDK in ubuntu

Question

I have successfully compiled this file and saved.

class A
{
    public static void main(String[] args)
    {
        System.out.println("Hey!"); 
    }
}

using

javac a.java

java A

but when I compile this file:

package B;

class A
{
    public static void main(String[] args)
    {
        System.out.println("Hey!"); 
    }
}

now, again using the same commands it do compile but never run

javac a.java

java A       
// could not find or load main class

Please guide me the exact command for the terminal to run the file.

Note: The file is named "a.java".

might be helpful - [package and folder names](http://stackoverflow.com/questions/8395916/package-name-is-different-than-the-folder-structure-but-still-java-code-compiles) — harshtuna, Mar 06 '15 at 13:04

score 2 · Answer 1 · answered Mar 06 '15 at 12:08

2

You need to specify the fully-qualified name, i.e. packageName.ClassName:

java B.A

answered Mar 06 '15 at 12:08

Eng.Fouad

Jens · Answer 2 · 2015-03-06T12:15:48.927

1

you have to change the directory to the directory wich contains the path 'B' (your package name) and than call java B.A

edited Mar 06 '15 at 12:15

answered Mar 06 '15 at 12:08

Jens

... and A.java must be saved in the path `./B/A.java` – Axel Mar 06 '15 at 12:10
1

No, `javac` doesn't require the package name. `java` does. – Eng.Fouad Mar 06 '15 at 12:11
I went to the directory, A.class is in the same location with a.java, thus again I am having the same error @Axel – Rohan Chauhan Mar 06 '15 at 12:18
@RohanChauhan you mist be in the directory that contans directory B and inside B must be A.class. – Jens Mar 06 '15 at 12:20
@Jens I dont have any directory inside my "java" directory in which I saved the a.java file. even when I use "cd B" its says, directory does not exist. – Rohan Chauhan Mar 06 '15 at 12:28
@RohanChauhan If you have a package B, so you must have the class in the directory 'B'. – Jens Mar 06 '15 at 12:31
I just created a directory and named it B, and stored the class A.class in it. Now it workd. I guess jdk donot create directory itself. So now its working – Rohan Chauhan Mar 06 '15 at 12:38
@RohanChauhan No jdk will not creating any directory. – Jens Mar 06 '15 at 12:39

Rohan Chauhan · Answer 3 · 2015-03-06T14:09:12.897

-1

As mentioned above, You need to specify the fully-qualified name, i.e. packageName.ClassName:

        >> javac a.java
        >> java B.A

But you need to create the directory named "packageName" yourself as jdk does not create one for you implicitly.

edited Mar 06 '15 at 14:09

answered Mar 06 '15 at 12:41

Rohan Chauhan

with `javac -d` it does - see [javac manual](http://docs.oracle.com/javase/8/docs/technotes/tools/unix/javac.html) – harshtuna Mar 06 '15 at 13:07

3 Answers3