Null pointer error in thread

Processing Coding Questions
28

using the register method, i’m still struggling with implementation, i’m following your example.

String [] messages = {"Test string for secondary thread",
                      "Here's another message.",
                      "And this is yet another thread."};
                      
int [] numbers = { 0,1,2,3,4,5,6,7,8,9,10};
int threads = 1;
                      
void setup(){
  size(200,200);
  
  for(int i=0;i<threads;i++){
    
    new Thread(new A(numbers)).start();
  }
};

void draw(){
  background(0);
  fill(255);
  text(frameRate,100,100);
};

class A implements Runnable {
  String to_print;
  int t,count = 0;;
  boolean ints,intss,strings;
  int [] numbers = new int[1];
  String [] messages = new String[1];
  
  A(String to_print) {
    this.to_print = to_print;
  };
  
  A(Integer t) {
    this.t = t;
    intss = true;
  };
  
  A(String [] messages) {
    this.messages = messages;
    strings = true;
  };
  
  A(int [] numbers) {
    this.numbers = numbers;
    ints = true;
  };
  
  public void run() {
    registerMethod("draw", this);
    draw();
  };
  
  public void draw(){
    unregisterMethod("draw", this);
  
    try {
      display();
    }
  
    catch (final AssertionError err) {
      System.err.println(err);
    }
  };
  
  void display(){
    while(true){
      count++;
    //if(ints)System.out.println(count);
    //displayMessages();
    displayNumbers();
  }
  };
  
  void displayMessages(){
    if(strings)
    for(int i=0;i<messages.length;i++){
      
    String message = messages[i];
    
    fill(255);
    text(message,100,100);
    }
  };
  
  void displayNumbers(){
    if(ints){
    //text(count,100,100);
    fill(255);
    rect(10,10,width-20,height-20);
    //System.out.println(count);
    //for(int i=0;i<numbers.length;i++){
      
    //int number = numbers[i];
    
    //fill(255);
    //text(numbers.length,100,100);
    //}
    }
  };
};