User entered input for array size, but array size doesn't equal user input

Question

Can anyone tell me why the array size of the titles array in the data definition class doesn't equal the value the user inputted that was passed in from the implementation class and set as an instance variable in the data definition class?

This is the Data Definition Class.

public class Photograph { 

   private int maxTakes;

   public Photograph() {
      this.titles = new String[this.maxTakes];
      numPhotosTaken = 0;
   }

   public void setMaxTakes(int maxTakes) {
      this.maxTakes = maxTakes;
   }

   public boolean setTitle(String title) {
      if (this.numPhotosTaken < this.titles.length) {
         this.titles[numPhotosTaken] = title;
         numPhotosTaken++;
         return true;
      }
      else {
         return false;
      }
   }
}

This is the implementation class.

import javax.swing.JOptionPane;

public class MakePhotographs {
   public static void main (String[] args) {
      Photograph photo;
      do {
         photo = create();
      } while (JOptionPane.showConfirmDialog(null, "Enter another couple?") == JOptionPane.YES_OPTION);
   }

   private static Photograph create() {
      Photograph photo = new Photograph();
      photo.setMaxTakes(Integer.parseInt(JOptionPane.showInputDialog("Enter maximum number of photos to take")));

      do {
         String title = JOptionPane.showInputDialog("Enter title of photo");
         if (!photo.setTitle(title)) {
            JOptionPane.showMessageDialog(null, "No more photos allowed!");
         }   
      } while (JOptionPane.showConfirmDialog(null, "Enter another photo?") == JOptionPane.YES_OPTION);
      return photo;
   }
}

Could you tell what makes you think that the size is not same? Output/Error Stack? — ninja.coder
– ninja.coder, Commented Mar 30, 2016 at 18:07
Your array is initialized in the constructor using the value maxTakes which, at the time the constructor is called, is 0. — KevinO
– KevinO, Commented Mar 30, 2016 at 18:07
When I try to enter a title of a photo, I'm always prompted with the error message, "No more photos allowed" — ush
– ush, Commented Mar 30, 2016 at 18:08

Yassin Hajaj · Accepted Answer · 2016-03-30 18:11:42Z

2

Create a constructor that takes in the maxTakes value and use that:

Photograph photo = new Photograph(Integer.parseInt(JOptionPane.showInputDialog("Enter maximum number of photos to take")));

You don't need the setMaxTakes anymore since it's been set within the constructor.

class Photograph { 

    private int maxTakes;
    private String[] titles;
    private int numPhotosTaken;

    public Photograph(int maxTakes) {
        this.maxTakes = maxTakes;
        this.titles = new String[maxTakes];
        numPhotosTaken = 0;
    }

    public boolean setTitle(String title) {
        if (this.numPhotosTaken < this.titles.length) {
            this.titles[numPhotosTaken] = title;
            numPhotosTaken++;
            return true;
        }
        else {
            return false;
        }
    }
}

edited Mar 30, 2016 at 18:11

Yassin Hajaj

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answered Mar 30, 2016 at 18:09

Gremash

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1 Comment

Gremash Over a year ago

I was actually in the middle of updating my answer to include the code that Yassin suggested but he beat me to it :)

Community · Accepted Answer · 2017-05-23 12:31:32Z

1

Your array is created before you can call setMaxTakes(). After you have already created your array with the length of maxTakes, changing the value of maxTakes does not accomplish anything.

You need to either change the method of setMaxTakes() to the following:

public void setMaxTakes(int maxTakes) {
    titles = new String[maxTakes];
}

or go with the answer posted by @Gremash here (which is the proper way to do it).

edited May 23, 2017 at 12:31

CommunityBot

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answered Mar 30, 2016 at 18:12

RaminS

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