Working with overloading but method does not return value. Any ideas?

Question

So I am currently taking a java course and yes I am new to java. I know some of this code will look redundant but it is what it is. So this week we are working with overloading with methods named the same thing but only accept certain data types. This is the main method I will use to call other java methods.

// This class uses a DebugBox class to instantiate two Box objects
public class DebugFour3
{
   public static void main(String args[])
   {
      int width = 12,
      length = 10,
      height = 8;
      DebugBox box1 = new DebugBox();
      DebugBox box2 = new DebugBox(width, length, height);
      System.out.println("The dimensions of the first box are");
      box1.showData();
      System.out.print("  The volume of the first box is ");
      showVolume(box1);
      System.out.println("The dimensions of the second box are");
      box2.showData();
      System.out.print("  The volume of the second box is ");
      showVolume(box2);
   }
   public static void showVolume(DebugBox aBox)
   {
      double vol = aBox.getVolume();
      System.out.println(vol);
   }
}

Now the first set of data that is present here works as it should and results in a volume of 1. After passing the information for the second box to the Second DeBugBox method it will not pass it to the get volume and return it. It just returns 0 for length width and height and volume.

public class DebugBox
{
   private int width;
   private int length;
   private int height;
   public  DebugBox()
   {
      length = 1;
      width = 1;
      height = 1;
   }
   public DebugBox(int width, int length, int height)
   {
      width = width;
      length = length;
      height = height;
      getVolume();
   }
   public void showData()
   {
      System.out.println("Width: "  + width +   " Length: " +
        length + " Height: "+ height);
   }
   public double getVolume()
   { 
      double vol = length * width * height;
      return vol;
   }
}

`return vol;` but you're calling `getVolume();` and assigning its returned value to... what exactly? — Federico klez Culloca, Feb 09 '20 at 10:18
Also, I'm not sure what this question has to do with overloading. — Federico klez Culloca, Feb 09 '20 at 10:19
@FedericoklezCulloca The OP probably meant the overloaded constructrors. — Eran, Feb 09 '20 at 10:20
@FedericoklezCulloca Yes it is assigned to the variable vol. That is what is returned. — Rick Cox, Feb 09 '20 at 10:43
Related: https://stackoverflow.com/questions/44286520/can-i-use-same-name-for-public-variable-and-method-argument-in-java and https://stackoverflow.com/questions/3728062/what-is-the-meaning-of-this-in-java — Mark Rotteveel, Feb 09 '20 at 10:43
@Eran That worked. I'm not sure why though. I will look it up. Thanks a bunch! — Rick Cox, Feb 09 '20 at 10:44
@RickCox yes, but it's doing nothing inside the constructor for `DebugBox`. So either you expected something else to happen (since `vol` inside `getVolume` gets destroyed as soon as the method ends) or it's just useless. Either way, something needs to be fixed. — Federico klez Culloca, Feb 09 '20 at 10:56

score 0 · Accepted Answer · answered Feb 09 '20 at 10:43

I don't think you need to call the getVolume() method in the overloaded constructor.

As @Eran was suggesting, try changing to this:

public DebugBox(int width, int length, int height)
{
   this.width = width;
   this.length = length;
   this.height = height;
}

The reason why you need to use this, is because you have named your constructor arguments the same as your class field properties, and therefore you need to reference your outside properties with the 'this' prefix.

Working with overloading but method does not return value. Any ideas?

1 Answers1