Initial state of vector (or array?), I do not understand

Processing Coding Questions
7

Ok I spotted two bugs. One with the boundary box conditions, the other with a wrong loop (or bracket).
Working code:

int num_points_dropplet = 1000;
int num_points_dropplet_2 = 10;
float[] x = new float[num_points_dropplet];
float[] y = new float[num_points_dropplet];
float[] x_2 = new float[num_points_dropplet_2];
float[] y_2 = new float[num_points_dropplet_2];
float[] dist_array = new float[num_points_dropplet];
float the_min = 1000;
int min_index = 0;
float distance_x;
float distance_y;
int count = 0;

int box_x = 10;
int box_y = 1000;
void settings() {
  System.setProperty("jogl.disable.openglcore", "true");
  size(box_x, box_y, P2D);
}

void setup() {
  frameRate(2);
  background(0);
  noFill();

  for (int i = 0; i<num_points_dropplet; i++) {
    float radius = random(15);
    float a = random(TWO_PI);    
    x[i] = -box_x/8.0 + cos(a)*radius+random(-radius/10.0, radius/10.0);
    y[i] = -box_y/8.0 + sin(a)*radius+random(-radius/10.0, radius/10.0);
    stroke(255);
    strokeWeight(2);
  }

  for (int j = 0; j<num_points_dropplet_2; j++) {
    float radius = random(10);
    float a = random(TWO_PI);
    float x_offset_2 = box_x/2.0;
    float y_offset_2 = box_y/2.0;
    x_2[j] = x_offset_2 + cos(a)*radius+random(-radius/10.0, radius/10.0);
    y_2[j] = y_offset_2 + sin(a)*radius+random(-radius/10.0, radius/10.0);
    stroke(255, 0, 0);
    strokeWeight(3);
  }
}
void draw() {
  background(0);
  translate(width/2, height/2);
  for (int i=0; i<num_points_dropplet; i++) {
    float radius = random(15);
    float a = random(TWO_PI);    
    x[i] += cos(a)*radius+random(-radius/10.0, radius/10.0);
    y[i] += sin(a)*radius+random(-radius/10.0, radius/10.0);

    if (x[i] <-box_x/2) {
      x[i] = -box_x/2;
    }
    if (x[i] >box_x/2) {
      x[i] = box_x/2;
    }
    if (y[i] <-box_y/2) {
      y[i] = -box_y/2;
    }
    if (y[i] >box_y/2) {
      y[i] = box_y/2;
    }
    stroke(255);
    strokeWeight(2);
    point(x[i], y[i]);
  }

  for (int j=0; j<num_points_dropplet_2; j++) {
    the_min = 100000; // reset value, otherwise the dots all agglutinate.
    for (int i=0; i<num_points_dropplet; i++) {
      dist_array[i] = dist(x[i], y[i], x_2[j], y_2[j]);
      // return the index of the min of the distances
      if (dist_array[i] < the_min) {
        the_min = dist_array[i];
        min_index = i;
      }
    }  
    float radius = random(1);
    float a = random(TWO_PI);

    // Move each point a little bit toward the other group's closest point.
    distance_x = x[min_index] - x_2[j];
    if (distance_x >0) {
      x_2[j] += cos(a)*radius + distance_x / 100.0;
    } else {
      x_2[j] += cos(a)*radius + distance_x / 100.0;
    }

    distance_y = y[min_index] - y_2[j];
    if (distance_y >0) {
      y_2[j] += sin(a)*radius + distance_y / 100.0;
    } else {
      y_2[j] += sin(a)*radius + distance_y / 100.0;
    }

    if (x_2[j] <-box_x/2) {
      x_2[j] = -box_x/2;
    }
    if (x_2[j] >box_x/2) {
      x_2[j] = box_x/2;
    }
    if (y_2[j] <-box_y/2) {
      y_2[j] = -box_y/2;
    }
    if (y_2[j] >box_y/2) {
      y_2[j] = box_y/2;
    }
    stroke(255, 0, 0);
    strokeWeight(3);
    point(x_2[j], y_2[j]);
  }
}
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