Re: Calling accessor from outside, but having noSuchMethodError
Merciadri Luca wrote:
I've got a Tableau.java file which contains a Tableau class defined
like this:
==
public class Tableau
{
public int dimension;
public int generations;
public Cell[][] setOfCells;
public Tableau(int n, int s) // this is an accessor
{
setOfCells = new Cell[n][n];
dimension = n;
generations = s;
}
// some methods
}
"public Tableau(int n, int s)" is not an accessor, it's a constructor.
Accessors allow access to the private attributes of an object.
Since you've declared all of your class's attributes (dimension,
generations, setOfCells) public, you probably don't understand why you
need accessor methods.
The attributes of a class should typcially be protected from the users
of that class, and safe reading and writing of the class's attributes
should be handled by the class.
So, you would have instead:
public class Tableau
{
private int dimension;
// ...
public Tableau(int n, int s) // this is a constructor
{
// ...
}
public int getDimension() // this is an accessor
{
return dimension;
}
// other methods...
}
The public cannot read or write dimension directly because it's
private, but they can use the public method getDimension() which, as a
class method, has direct read access to dimension.
Assuming you don't create a public method that allows a user to change
the value of dimension, this ensures that the dimension of a Tableau
object will not change once it has been established with the
constructor.
==
I then need to instantiate a Tableau, in another file; I do it like
this: ==
Tableau tableau = new Tableau(n, s); // this is l.41
// other things
==
The problem is that I get, after launching the bytecode,
==
Exception in thread "main" java.lang.NoSuchMethodError:
Tableau.<init>(II)V at
userErrorHandling.checkArgsTypesValues(userErrorHandling.java:41)
[etc.] ==
As for your actual question, I cannot reproduce your error with the
amount of information you've provided. My code's instantiation of
tableau works fine. The error must be somewhere in the code you've
omitted from the post.