1. 
       /*
       Node pane
       */
      
       class Node {
      
         int node_x;  // x Position
         int node_y;  // y Position
         int node_w;   // width
         int node_h;   // height
         String node_name;  // name of the node
        
         Node(int temp_node_x, int temp_node_y, int temp_node_number){
              
           node_x = temp_node_x;
           node_y = temp_node_y;
           node_w = 100;
           node_h = 36;
           node_name = Integer.toString(temp_node_number);  //integer to string
      
         }
        
         void display(){
          rectMode(CENTER);
           fill(MID_GRAY);
           rect(node_x, node_y, node_w, node_h);    //button
         
           fill(BLACK);    //text color black
           text(node_name, node_x, node_y+6); //button text
         rectMode(CORNER); // reset
         }
      
       }

and this is how i call the class

1. 
         }else if (current_tab == "Node"){    // If the current tab is Node tab then do
        
        
               //for (int i = listofNodes.size()-1; i >= 0; i--) {   
                 for(int i = 0; i < listofNodes.size();i++){         // Loop through the ArrayList.           
                 Node currentNode = (Node) listofNodes.get(i);       // To be able to access the methods for the ArrayList element at the position 'i'
                 currentNode.display();                              // Call the display() method for the object pointed at by currentNode
               }  // End of for loop
              
              
         }else if (current_tab == "Move"){    // If the current tab is Move tab then do something
           //

1. 
       void mousePressed() {
          
         /*
         Used for node class
         Create new buttons
         */
        
         if (mouseY >= 25 && current_tab == "Node") {
           listofNodes.add(new Node(mouseX, mouseY, nodecounter++));  //
         }
        
        
       }