Syntax error on token "class", Identifier expected

I have 2 tabs on my Processing program. I actually copied and pasted the exact code from a YouTube tutorial and keep getting the error message when I run.

Tab 1:

class Bubble {    

float x;
float y;

Bubble (){
  x=width/2;
  y=height; 
}

void ascend (){
  y--;
}

void display() {
  stroke(0);
  fill(127); 
  ellipse(x,y,64,64); 
  }      
}

Tab2:

Bubble b; 

void setup() {
  size(640,360); 
  b=new Bubble();
}

void draw () {
  background(255); 
  b.ascend();
  b.display();
  //b.top();
}

The error message says that:

Syntax error on token "class", Identifier expected