You want to create a class or to copy/paste it?
Have you tried something (if so, what?). What is stopping you? What is the use of your class? (looks like a simple rect() can do the same thing...) Well, is that homework (looks like so)?

1. import peasy.org.apache.commons.math.*;
2. import peasy.*;
3. import peasy.org.apache.commons.math.geometry.*;
4. 
   
5. 
   
6. Mesh mymesh;
7. PeasyCam cam;
8. 
   
9. void setup() {
10.   size(400,400,P3D);
11.   cam = new PeasyCam(this, 400);
12.   cam.setMinimumDistance(200);
13.   cam.setMaximumDistance(1000);
14.   smooth();
15.     mymesh = new Mesh(20,20); // initializing 2D Lattice Size
16. }
17. 
    
18. 
    
19. 
    
20. 
    
21.   void draw() {
22.     background(0);
23. 
    
24. 
    
25.     mymesh.startRndArray(); //Initialize Lattice nodes at random position
26.     mymesh.display();      // Render Lattice
27.   }

MESH CLASS

              
               
                
                 
                  class Mesh {
                  
  // Components Field
                 
                
               
              

 

  PVector[][] matrix;
  int w,h;

 

  // Default Constructor
  Mesh (int w_t, int h_t) {
    w = w_t;
    h = h_t;
   
    matrix = new PVector[w][h];
   
   
   
  }

 

  // Start Lattice  nodes at random position
  void startRndArray() {
    for (int i=0; i<w; i++) {
      for(int j=0; j<h; j++) {
        matrix[i][j] = new PVector(random(0,width), random(0,height), random(0,height));
      }
    }
  
  }
 

 

  void display() {  
 lights();
  noStroke();

 

    for (int i=0; i<w-1; i++) {
      for(int j=0; j<h-1; j++) {
        fill(255);
        beginShape(QUADS);
        vertex (matrix[i][j].x,     matrix[i][j].y,     matrix[i][j].z);
        vertex (matrix[i+1][j].x,   matrix[i+1][j].y,   matrix[i+1][j].z);
        vertex (matrix[i+1][j+1].x, matrix[i+1][j+1].y, matrix[i+1][j+1].z);
        vertex (matrix[i][j+1].x,   matrix[i][j+1].y,   matrix[i][j+1].z);
        endShape();
      }
    }
  }

error found

Yes, I was ironical, but not flaming. As stated, the original message was missing information: you mention 2D mesh and show a 3D sketch! Well, you solved your problem (after showing your code, as I wrote...), so all is well.