Help with static methods!

michaelberge · 2018-07-31T05:48:20.112Z

I’m getting an error that says ‘No enclosing instance of type ____ is accessible’. I basically want a class that has both non-static and static variables but Processing doesn’t allow that for some reason. I tried putting static methods in the Matrix class but I still got an error.

static class Matrix_Static {
   // Multiply Matrix m1 by Matrix m2
  static Matrix multiply(Matrix m1, Matrix m2) {
    // Matrix Product (a • b)
    if(m1.cols == m2.rows) {
       Matrix result = new Matrix(m1.rows, m2.cols);
      for(int i = 0; i < result.rows; i++) {
        for(int j = 0; j < result.cols;j++) {
          float sum = 0;
          for(int k = 0; k < m1.cols; k++) {
            sum += m1.data[i][k] * m2.data[k][j];
          }
          result.data[i][j] = sum;
        }
      }
      return result;
    } else {
      println("error - conflicting dimensions");
      return null;
    }
  }
}

class Matrix extends Matrix_Static {
  int rows, cols;
  float[][] data;
  
  // Constructor 1
  Matrix(int rows, int cols) {
    this.rows = rows;
    this.cols = cols;
    this.data = new float[rows][cols];
    
    for(int i = 0; i < rows; i++) {
      for(int j = 0; j < cols;j++) {
        this.data[i][j] = 0;
      }
    }
  }

tony · 2018-07-31T05:54:37.970Z

Assuming this is Java, it sounds like you’re more concerned with how static methods and variables in Java.

Can I ask what you already know about building classes and using static methods/variables?

Also, to add code, surround the code with triple tildes

jb4x · 2018-07-31T05:56:55.508Z

Hi!
Can you please format your code using the </> button please?

Also, you can go have a look here for more general informations about posting:

Guidelines—Asking Questions Community

Summary (TL;DR) Ask complete questions to get better answers! Be specific. For example: I want to load an image. I tried using createImg() , and I expected the image to be on canvas, but what happened instead was the image showing up below the canvas. Isolate your problem and work in small steps. Share only the code directly related to your problem if it is part of a bigger project, and if something isn’t working, try the smallest code that could do the thing you want. Can we run your code …

michaelberge · 2018-07-31T06:00:17.212Z

Thanks for replying so quickly! So I have this Matrix class with a bunch of non-static methods that can only be called with an instance of a matrix class, but I want to add a static classes within the Matrix class so I can add, say, a method which is called multiply which takes 2 matrices and multiplies them together. This static method would be called by: Matrix.multiply(m1, m2); which would return a new Matrix. Processing does not allow me to do this for some reason…

tony · 2018-07-31T06:12:32.927Z

Have you got it to work without implementing the class as a static class? I’ll be honest, I’m not an expert, but from my understanding, using static methods is generally a performance thing.

My advice? Try to get it working without static elements, and then implement static elements.

jb4x · 2018-07-31T06:41:56.270Z

In Java the keyword static does not have the same meaning as in c# for example and you can’t create an outer static class. The keyword should be used only for inner classes. See that link for further explanation:

caveofprogramming.com

Java Static Class: A Tutorial on Static Classes in Java

Java, C++ and Perl Tutorials - Learn to program

PS: Again, can you please format your code in your first post? It is not because I was not giving you solution in my previous post that you need to ignore what is writtent in it…

GoToLoop · 2018-07-31T06:50:20.938Z

Processing Foundation – 9 Jun 18

Deeply-layered nested classes

Hello. I’m trying to make nested classes to make some sort of system in my classes. I am working insode Visual Studio Code, where you can hide lines of code. When I try: static class A{ static class B{ class C{ C(){} ...

Reading time: 2 mins 🕑 Likes: 8 ❤