Chapter 1 Exercise

[Dorian Franklin]

I need help figuring out where to type this code and how to execute it.  I have the Zoo.java file  This is what I have so far:


package zoo;

public class Zoo {
   public static void main(String[] args) {
       System.out.println("Welcome!!!");
   }
   
} $javac Zoo.java
$java Zoo


This is what I was instructed to do: To compile and execute this code, type it into a file called Zoo.java and execute the following:
$ javac Zoo.java
$ java Zoo

[Paul Clements]

Your Zoo.java file is wrong:

package zoo; 

public class Zoo { 
    public static void main(String[] args) { 
        System.out.println("Welcome!!!"); 
    } 
    
}$javac Zoo.java
$java Zoo

Line 8 should be "}", and line 9 should be deleted i.e. code should be:

package zoo; 
public class Zoo { 
    public static void main(String[] args) { 
        System.out.println("Welcome!!!"); 
    }     
}

[Paul Clements]

As an aside you could use an IDE like Eclipse or NetBeans to create your java code. This would save the need to run manual compiles/runs i.e. java/java

[Knute Snortum]

It's more complicated than that because there is a package statement.  I would do this:

mkdir zoo mv Zoo.java zoo javac zoo/Zoo.java java zoo.Zoo

The package statement is saying that there is a subdirectory called zoo with a class call Zoo.  

javac zoo/Zoo.java compiles the file "zoo/Zoo.java" in the zoo directory.  

java zoo.Zoo will look for a class file that is in the subdirectory zoo called Zoo.class.

[Paul Clements]

End of previous post should read:

"This would save the need to execute manual compiles/runs i.e. enter javac/java at the command prompt"

[Junilu Lacar]

and Welcome to the Ranch, Dorian Franklin!

[Dave Tolls]

Paul Clements wrote:End of previous post should read:

"This would save the need to execute manual compiles/runs i.e. enter javac/java at the command prompt"

I think learning to compile and run (very) basic code from the command line has its advantages.
If nothing else it gives you a good idea of what Java expects the structure of the code (as in files and folders) needs to look like, as well as a better grasp of classpaths than you would get from an IDE.

[Paul Clements]

Dave Tolls wrote:I think learning to compile and run (very) basic code from the command line has its advantages.
If nothing else it gives you a good idea of what Java expects the structure of the code (as in files and folders) needs to look like, as well as a better grasp of classpaths than you would get from an IDE.

That's a valid point. For my own purposes I've been happy to use Eclipse. The project explorer gives a good graphical overview of what is where. In addition a quick trip into Windows Explorer confirms what Eclipse shows. That and I can't stand the command prompt window :-)