1. void keyPressed() {
   
2.  if (key == 'b' || key == 'B') {
   
3. // ellipse 1
   
4. }
5. else if (key == 'b' || key == 'B') {
6.  // ellipse 2
   
7. }
8. }

see
http://www.processing.org/reference/keyPressed_.html
etc. 

1. ArrayList<Ball> balls = new ArrayList<Ball>();
2. float gravity = 0.1; 
3. //arrays are used to store objects, and an array list can be used to make multiple objects, as it can increase better then a normal array
4. float lightvalue = 0;
5. //the light value will be used to change the light type, 0 for regular lights function, 1 for directional, 2 for ambient, 3 for spot light. To change the light, press Enter
6. float ballsize = 10;
7. //this will be used to determine the size of the spheres upon when they are made
8. float rX;
9. float rY;
10. // two variables specifying random values in the x and y value. rX is x value and rY is y value
11. PFont f;
12. String[] myStrings;
13. int time;
14. int i;
15. String dna;
16. void setup() {
17.   size(1500, 700, P3D);
18.   // start with one ball
19.   balls.add( new Ball(width/2, 0, 0));
20.   frameRate(60);
21.   background(0);
22.   f = createFont("Arial", 16, true); // Arial, 16 point, anti-aliasing on
23.   myStrings = loadStrings( "balls.txt" );
24.   time = millis() + 500;
25.   i = 0;
26.   String[] myStrings = loadStrings("balls.txt");
27.   // This is because we are deleting elements from the list.
28. }
29. //The key pressing here is used to try and change the the lightvalue, to later change the lights
30. void keyPressed() {
31.   if (key == ENTER || key == RETURN) {
32.     lightvalue = lightvalue + 1;
33.     lightvalue %= 4; // 0 1 2 3 0 1 2 ...
34.   }
35.   if (key >= '0' && key <= '9') {
36.     ballsize = (int(key) - int('0')) * 10;
37.     if (ballsize == 0) ballsize = 100;
38.   }
39.   if (key == 'r' || key == 'R' ) {
40.     rX = random(width);
41.     rY = random(height);
42.     balls.add( new Ball(rX, rY, 0));
43.   }
44. }
45. void draw() {
46.   background(0);
47.   textFont(f, 24);
48.   text ( "Welcome to the Sphere Simulator!", 0, 24);
49.   text ( "Click on the screen to generate a sphere!", 0, 48);
50.   text ( "Press the keys 1 through 0 to increase the size!", 0, 72);
51.   text ( "Press the R key to generate a sphere randomly!", 0, 96);
52.   text ( "Press Enter/Return to change the lights!", 0, 120);
53.   text( myStrings[i], 20, 650);
54.   if ( millis() > time ) {
55.     i++;
56.     i%=myStrings.length;
57.     time=millis() + 1000; 
58.     if (myStrings[i].equals("a")) {
59.       balls.add( new Ball(500, 100, 0));
60.     }
61.   }
62.   if (lightvalue == 0) {
63.     lights();
64.   }
65.   if (lightvalue == 1) {
66.     ambientLight(0, 0, 255);
67.   }
68.   if (lightvalue == 2) {
69.     directionalLight(0, 255, 0, mouseX, mouseY, 0);
70.   }
71.   if (lightvalue == 3) {
72.     spotLight(255, 0, 0, width/2, height/2, 400, 0, 0, -1, PI/2, 2);
73.   }
74.   // Ball is the datatypye of the stuff in the Array, b is the temporary name for each element in the array, balls is the name of the array to iterate through
75.   for ( int i=balls.size()-1; i>=0; i--) { //update() and dislay() are methods, in which b is using, and the dot "." connects the two, allowing b to use the two methods
76.     balls.get(i).update();  //update is used to improve the falling of the balls
77.     balls.get(i).display(); //display is used to make the balls, constantly
78.     if ( balls.get(i).isDead() ) {
79.       balls.remove(i);
80.     }
81.   }
82. }
83. void mousePressed() {
84.   balls.add(new Ball( mouseX, mouseY, 0));
85.   //this adds the object
86. }
87. class Ball {
88.   float x;
89.   float y;  
90.   float z;  
91.   float speed;  
92.   int t;
93.   // a constructor:
94.   Ball(float _x, float _y, float _z) {
95.     x     = _x;
96.     y     = _y;
97.     z     = _z;
98.     speed = 0;
99.     t = millis() + 5000;
100.   }
101.   void display() {
102.     noStroke();
103.     pushMatrix();
104.     translate(x, y, z);
105.     sphere(ballsize);
106.     popMatrix();
107.   }
108.   void update() {
109.     y = y + speed;
110.     speed = speed + gravity;
111.     if (y > height) {
112.       speed = speed * -0.65;
113.     }
114.   }
115.   boolean isDead() {
116.     return( millis() > t );
117.   }
118. }
119. //