@@ -15,7 +15,6 @@ ArrayList<ParticleSystem> systems;
 void setup() {
   size(640, 360);
   systems = new ArrayList<ParticleSystem>();
-  smooth();
 }
 
 void draw() {
 
@@ -1,6 +1,5 @@
 // An ArrayList is used to manage the list of Particles
 // An Iterator is used to remove "dead" particles while iterating over the list
-import java.util.Iterator;
 
 class ParticleSystem {
 
@@ -15,14 +14,14 @@ class ParticleSystem {
     }
   }
 
+
   void run() {
-    // Cycle through the ArrayList using Iterator, because we are deleting while iterating
-    Iterator<Particle> it = particles.iterator();
-    while (it.hasNext()) {
-      Particle p = it.next();
+    // Cycle through the ArrayList backwards, because we are deleting while iterating
+    for (int i = particles.size()-1; i >= 0; i--) {
+      Particle p = particles.get(i);
       p.run();
       if (p.isDead()) {
-        it.remove();
+        particles.remove(i);
       }
     }
   }
@@ -32,7 +31,8 @@ class ParticleSystem {
     // Add either a Particle or CrazyParticle to the system
     if (int(random(0, 2)) == 0) {
       p = new Particle(origin);
-    } else {
+    } 
+    else {
       p = new CrazyParticle(origin);
     }
     particles.add(p);
@@ -46,5 +46,5 @@ class ParticleSystem {
   boolean dead() {
     return particles.isEmpty();
   }
+}
 
-}
Original file line number	Diff line number	Diff line change
@@ -15,7 +15,6 @@ ArrayList<ParticleSystem> systems;
15	15	void setup() {
16	16	size(640, 360);
17	17	systems = new ArrayList<ParticleSystem>();
18		- smooth();
19	18	}
20	19
21	20	void draw() {
Original file line number	Diff line number	Diff line change
@@ -1,6 +1,5 @@
1	1	// An ArrayList is used to manage the list of Particles
2	2	// An Iterator is used to remove "dead" particles while iterating over the list
3		- import java.util.Iterator;
4	3
5	4	class ParticleSystem {
6	5
@@ -15,14 +14,14 @@ class ParticleSystem {
15	14	}
16	15	}
17	16
	17	+
18	18	void run() {
19		- // Cycle through the ArrayList using Iterator, because we are deleting while iterating
20		- Iterator<Particle> it = particles.iterator();
21		- while (it.hasNext()) {
22		- Particle p = it.next();
	19	+ // Cycle through the ArrayList backwards, because we are deleting while iterating
	20	+ for (int i = particles.size()-1; i >= 0; i--) {
	21	+ Particle p = particles.get(i);
23	22	p.run();
24	23	if (p.isDead()) {
25		- it.remove();
	24	+ particles.remove(i);
26	25	}
27	26	}
28	27	}
@@ -32,7 +31,8 @@ class ParticleSystem {
32	31	// Add either a Particle or CrazyParticle to the system
33	32	if (int(random(0, 2)) == 0) {
34	33	p = new Particle(origin);
35		- } else {
	34	+ }
	35	+ else {
36	36	p = new CrazyParticle(origin);
37	37	}
38	38	particles.add(p);
@@ -46,5 +46,5 @@ class ParticleSystem {
46	46	boolean dead() {
47	47	return particles.isEmpty();
48	48	}
	49	+ }
49	50
50		- }