Exception in thread "Animation Thread" java.lang.NullPointerException
    at I2C_Plot.setup(I2C_Plot.java:33)
    at processing.core.PApplet.handleDraw(Unknown Source)
    at processing.core.PApplet.run(Unknown Source)
    at java.lang.Thread.run(Thread.java:636)

import processing.net.*;

Client C;
String data;
int X = 1;
int[] Old;
int[] Now;
 
void setup() {
  size(600,200); smooth(); background( 0 );
  C = new Client( this, "127.0.0.1", 5204 );
  Old[0] = 0;
  }
 
void draw() { }

void clientEvent( Client C ) {
  println("Event"); int Yes;
  while( ( Yes = C.available() ) > 0 )  {
    println("read: " + Yes);
    data = C.readStringUntil( '\n' );
    print(data);
    Now = int( splitTokens( data, " \n" ) );
    println(data);
    if( Now[0] != Old[0] ) { line( X, 10, X, 20 ); }
    point( X, 10 + ( Now[0] * 10 ) );
    Old[0] = Now[0];
    if( ++X > 600 ) X = 1;
 }
}