Re: Array of something

Lew <>
Fri, 25 Mar 2011 15:17:37 -0400
Merciadri Luca wrote:

I am defining a `Tableau' array of `Cell' elements. Tableau and Cell

Show us some code. I don't know what you mean by "a `Tableau' array of `Cell'

are both classes, and some methods over `Tableau' and `Cell' are

Now, my Cell class comprises a State so that to each Cell
instanciation a State is associated, i.e. one can make

Cell myCell = new Cell();

What do you expect to happen as a result of that standalone expression?


Now, for the `Tableau' array, if I need to access a Cell's state, do I need to write, for a `Tableau'
element: myTableau.cell.state? It would mean that a `cell' (of type
Cell) is defined for each `Tableau' element, and that is not the
case. But using myTableau.state would mean that `state' is a variable of
myTableau (of type `Tableau'), which is not the case too, because
state is defined for each Cell element.

Remember that a reference variable can have a value of 'null', and member
variables always start at their "zero" value, which for references is 'null'.

Whatever you do to get a 'Cell', it's clearly 'Cell#state' that you want.

Show us class definitions. You're not speaking Java so it's really, really
hard to figure out what you need help with.

You can have something like this:

  package tableaux;
  public class Tableau
    /* p-p */ Cell [] cells;


  package tableaux;
  public class Cell
    /* p-p */ State state;

Your code to access individual 'Cell' state would be similar to:

  package tableaux;
  import org.apache.log4j.Logger;
  import static org.apache.log4j.Logger.getLogger;

  public class Processor
   /* p-p */ Tableau tableau;

   // various setter methods that should give 'tableau' a value

   public void process()
     if ( tableau == null || tableau.cells == null )
     for ( Cell cell : tableau.cells )
       if ( cell != null && cell.state != null )
         doSomethingWith( cell.state );

I'm ignoring the convention and best practice to use accessor and mutator
(getter and setter) methods instead of raw access to fields. I did not ignore
variable accessibility; I deliberately chose package-private
('/* p-p */') access.

Honi soit qui mal y pense.

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