problem the display of processing IDE, the after it run, the texts are gone

IDK what just happen, but when the program is still running, the text the after it showed it gone, or it just showed one text. can u guys help me sorry for my bad English, I'll be appreciated your help thank you so much this is my code

int j;
float timeinterval;
float lasttimecheck;
float endY = 0;
int index = 0;
int x2;
int y2;
int x0=150;
int y0=0;
float r = random(1, 20);
float x1 = 1;
float y1 = 1;
String[] words;

void timecapture() {
  lasttimecheck = millis();
  timeinterval = 0; //2sec
}

void setup() {
  size (400, 400);
  timecapture();
  frameRate(5);
   stroke(0);
}

void draw() { 
  background(255);

  textSize(20);
  int y2 = 0; 
  float [] x = new float [j];
  float [] y = new float [j];


  for (int i = 0; (i<x.length) && (i<y.length); i++ ) {
    x[i] = x1;
    y[i] = y1;
    fill(0);
    //text (x[i]+","+y[i], 20, y1);
  }

  y2 = y2+40;

  String[] data = new String[x.length];
  for (int ii = 0; ii<x.length; ii++) {
    data [ii] = str(x[ii]) + ("\t") + str(y[ii]);
  }
  if (millis() > lasttimecheck + timeinterval) {
    saveStrings("location", data);
    lasttimecheck = millis();
  }
    if (x.length<30 && y.length<30)
    j=j+1;
    x1=x1+r; y1=y1+r; 
 }

The issue is that the arrays x and y are recreated in every frame.

void draw() { 
 background(255);

 // [...]

 float [] x = new float [j];
 float [] y = new float [j];

Add global variables x, y and data. Use append() to add values to the arrays. And draw the text in a loop:

float [] x = new float [0];
float [] y = new float [0];
String[] data = new String[0];

void draw() { 
    background(255);

    textSize(20);
    for (int i = 0; (i<x.length) && (i<y.length); i++ ) {
        fill(0);
        text (x[i]+","+y[i], 20, i*20 + 20);
    }

    if (x.length <= j) { 
        x = append(x, x1);
        y = append(y, y1);
        data = append(data, str(x1) + ("\t") + str(y1));
    }

    if (millis() > lasttimecheck + timeinterval) {
        saveStrings("location", data);
        lasttimecheck = millis();
    }

    if (x.length<30 && y.length<30) {
        j=j+1;
    }
    x1=x1+r; y1=y1+r; 
}