Thanks for your help, all right!

I now have this question:
How do I know when I released "4 - 3 = "
each string must be known and therefore:

String insieme[0] = {"4 - 3 ="};

String insieme[1] = { "5 - 2 ="};

but I miss declare the list of String insieme[i]

sorry but I just started with Processing,

I hope in your help.

thanks phi.lho,

The random string added to form NyARToolkit works but can not see, maybe I entered something wrong?

/** NyARToolkit for proce55ing/0.3.0
 (c)2008-2010 nyatla
 airmail(at)ebony.plala.or.jp
*/

import processing.video.*;
import jp.nyatla.nyar4psg.*;
import processing.opengl.*;
import javax.media.opengl.*;

Capture cam;
NyARBoard nya;
NyARBoard nya2;
NyARBoard nya3;
NyARBoard nya4;
NyARBoard nya5;

PFont testo;

String insieme[] = new String[2];

ArrayList charHolder;
ArrayList buffer;

void setup() {
  size(800,600,OPENGL);
  insieme[0] = "4 - 3 =";
insieme[1] = "5 - 2 =";
    charHolder = new ArrayList();
  buffer = new ArrayList();
  for(int i = 0; i< insieme.length;i++){
   charHolder.add(insieme[i]);
  }
   testo = createFont("FFScala", 32);
   textFont (testo,100);
   textAlign (CENTER,CENTER);
   frameRate(10);

  colorMode(RGB, 100);
  testo = createFont("FFScala", 32);

  cam=new Capture(this,width,height);
 
  // Primo
  nya=new NyARBoard(this,width,height,"camera_para.dat","patt.uno",80);
  print(nya.VERSION);
  nya.gsThreshold=120;//画像２値化の閾値(0<n<255) default=110
  nya.cfThreshold=0.4;//変換行列計算を行うマーカ一致度(0.0<n<1.0) default=0.4

 

}

void draw() {
 background(255);

  if (cam.available() !=true) {
    return;
   
   
  }
   cam.read();
  hint(DISABLE_DEPTH_TEST);
  image(cam,0,0);
  hint(ENABLE_DEPTH_TEST);

fill(0, 102, 153);
 
  
  //Primo
  if(nya.detect(cam)) {
    hint(DISABLE_DEPTH_TEST);
    //一致度を書く
    textFont(testo,25.0);
    fill((int)((1.0-nya.confidence)*100),(int)(nya.confidence*100),0);
    text((int)(nya.confidence*100)+"%",width-60,height-20);
    //マーカの角度、水平位置等
    pushMatrix();
    textFont(testo,10.0);
   // fill(0,100,0,80);
    translate((nya.pos2d[0][0]+nya.pos2d[1][0]+nya.pos2d[2][0]+nya.pos2d[3][0])/4+50,(nya.pos2d[0][1]+nya.pos2d[1][1]+nya.pos2d[2][1]+nya.pos2d[3][1])/4+50);
 
    popMatrix();   
    //マーカの位置を描画
    //drawMarkerPos(nya.pos2d);
    hint(ENABLE_DEPTH_TEST);
   
    PGraphicsOpenGL pgl = (PGraphicsOpenGL) g;
    nya.beginTransform(pgl);//マーカ座標系での描画を開始する。
    //ここからマーカ座標系
    stroke(255,200,0);
    translate(0,0,20);
    box(40);
    nya.endTransform();//マーカ座標系での描画を終了する。（必ず呼んで！）
  }

 if (keyPressed == true) {
   int index = floor(random(charHolder.size()));
    text ((String)charHolder.get(index),200 , 100);
    buffer.add(charHolder.remove(index));
  }
  if(charHolder.size() == 0){
   charHolder = (ArrayList)buffer.clone();
   buffer.clear();
  }

  
 }