ggkmath

I’m working through the example here:

http://www.vogella.com/articles/JavaPDF/article.html

In my file, I’ve got:

package com.mycompanyname.mydirectory;

import com.mycompanyname.OneOfMyClasses;
import com.itextpdf.text.Document;
...

 public class MyClass {
     ...
 }

Everything is working fine. What I don’t understand is that since I just copied the import statement directly from the link above for the iText portion — why does com.itextpdf.text.Document work?

I mean, if I look in directory com.mycompanyname I can see OneOfMyClasses.java there.

But in the com directly, there is no itextpdf directory (although maybe my user doesn’t have permission to see it(?)).

Hoping someone can help me understand what I’m missing here. Doesn’t the import point to a specific directory that I should be able to see the class? Is there a different com directory somewhere that iText is using, and com.itextpdf.text points to there? (if so, where’s the directory located)?

I installed the jar file for iText in the lib folder as per usual, and made sure it was included in the classpath.

Sam Peterson

I still don’t fully understand where I’m required to use the “public static void main(String[] args)” header within the .java files of a project. Do you need to put that header in every .java file of a package?

I have been following along with chapter 3 in my book, dragging and dropping downloaded stand alone book source files into my project’s package, but some of the .java files in my package don’t like that “public static void main(String[] args)” statement, even though my opening and closing curly braces are in the correct place. Here’s an example of one of those files (the ERROR(S) are described in the code’s comments):

    public class Rectangle
{
   public static void main(String[] args){
   private double length;//ERROR: illegal start of expression
   private double width;

   /**
    * Constructor
    */

   public Rectangle(double len, double w)
   {
      length = len;
      width = w;
   }

   /**
    * The setLength method accepts an argument
    * that is stored in the length field. 
    */

   public void setLength(double len)
   {
      length = len;
   }

   /**
    * The setWidth method accepts an argument
    * that is stored in the width field.
    */

   public void setWidth(double w)
   {
      width = w;
   }

   /**
    * The set method accepts two arguments
    * that are stored in the length and width
    * fields.
    */

   public void set(double len, double w)
   {
      length = len;
      width = w;
   }

   /**
    * The getLength method returns the value
    * stored in the length field.
    */

   public double getLength()
   {
      return length;
   }

   /**
    * The getWidth method returns the value
    * stored in the width field.
    */

   public double getWidth()
   {
      return width;
   }

   /**
    * The getArea method returns the value of the
    * length field times the width field.
    */

   public double getArea()
   {
      return length * width;
   }

}//end of: public static void main(String[] args)

}//end of: public class Rectangle  ERROR: class, interface, or enum expected

The ERROR(S) came up after I added the “public static void main(String[] args)” to the existing Rectangle.java file. Any idea of why this occurs?

user1552308

public int Gauss_Jordan(double[][] matrix, int numOfRows, int numOfCols) {
    for (int col_j = 0; col_j<numOfCols; col_j++) {
        row_i = nonzeros ++;
        System.out.println(row_i+" and "+nonzeros);
    }
    //return matrix;

    return 0;
}

up above in the method called “Gauss_Jordan”, you can see a for loop where it iterates until a certain condition is met. (duh.. lol sorry).

so i set row_i = nonzeros++ but here’s the thing, when I print out each iteration i get

• 0 and 1,
• 1 and 2,
• 2 and 3

. I would expect the output to be:

• 1 and 1,
• 2 and 2,
• 3 and 3.

How come this is not the case?

SkyVar

What I am trying to do is access information (variables, methods, etc) from a superclass and it’s subclasses.

If, what I know about inheritance is right, by accessing the superclass we have access to it’s subclasses by default. So I am thinking that I only need to be able to access the parent (super) class.

But how do I do that?

I am not going to post all the code up here, and that will turn this post into 3 pages.

The superclass is just a general code to create a contact and the class that needs to access the superclass is a class that creates an arraylist and records each contact in the arraylist.

I am not trying to get the code written for me, but all the help to understand how this will work, will be greatly appreciated.

To keep this short, I won’t post the subclasses unless needed.

Contacts (Superclass):

public class Contacts
{
    protected String fname;
    protected String lname;
    protected String email;
    protected String phone;

    public Contacts(String fname, String lname, String email, String phone)
    {
        this.fname=fname;
        this.lname=lname;
        this.email=email;
        this.phone=phone;

    }

    public String getfname()
    {
        return fname;
    }

    public void setfname(String first)
    {
        this.fname=first;       
    }

    public String getlname()
    {
        return lname;
    }

    public void setlname(String last)
    {
        this.lname=last;
    }

    public String getemail()
    {
        return email;
    }

    public void setemail(String e)
    {
        this.email=e;
    }

    public String getphone()
    {
        return phone;
    }

    public void setphone(String num)
    {
        this.phone=num;
    }

    public String getFullName()
    {
        String full=fname+" "+lname;
        return full;
    }

I haven’t done much on this code because I have been trying to figure it out without really knowing where to start. I do not think the arguments should be null, I just included those to satisfy the evil compiler.

Addressbook:

import java.util.ArrayList;
public class AddressBook
{
    Contacts enteredContact = new Contacts(null, null, null, null);
}

Here is one of the subclasses to get an idea of what is included.

Friends (subclass):

public class Friend extends Contacts
{
    private String dob;

    /**
     * Constructs a new Friend object. (Insert any further description that is needed)
     * @param fname
     * @param lname
     * @param email
     * @param phone
     */
    public Friend(String fname, String lname, String email, String phone)
    {
        super(fname, lname, email, phone);
    }

    /**
     * @return the dob
     */
    public String getDob()
    {
        return dob;
    }

    /**
     * @param dob the dob to set
     */
    public void setDob(String dob)
    {
        this.dob = dob;
    }

    /* (non-Javadoc)
     * @see java.lang.Object#toString()
     */
    @Override
    public String toString()
    {
        return fname+", "+lname+", "+email+", "+phone+", "+dob;
    }

}