I'm new to Programming. After a hour of searching i didn't find a answer.

How can I raise a value on a key press?

I like to add (and on another button subtract) a 1 to the "steer"-value, to calibrate my steering for my RC-car which is attached via XBEE to Arduino.

I hope someone can help me.

btw: sorry for my bad english

2. /*  RC car project | Arduino UNO | zH32
3.    
4. */
5. import processing.serial.*;
6. import controlP5.*;
7. import procontroll.*;
8. import net.java.games.input.*;
9. import java.io.*;
10. 
    
11. ControlP5 controlP5;
12. ControllIO controll;
13. ControllDevice device;
14. ControllStick stick;
15. ControllStick stick1;
16. ControllButton button1;
17. ControllButton button;
18. 
    
19. Serial myPort;
20. void setup()
21. {
22.   println(Serial.list());
23.   
24.   size(1024,600);
25.   myPort = new Serial(this, "COM32", 57600);
26.  
27. 
    
28.   frameRate(20);
29.   
30.   PFont myFont;
31.   myFont = createFont("Arial", 20);
32.   textFont(myFont);
33.   controlP5 = new ControlP5(this);
34.   controlP5.addSlider("Lenkung in %",-100,100,50,10,50,400,40);
35.   controlP5.addSlider("Power in %",-100,100,100,30,150,40,400);
36.   controlP5.addSlider("Licht",0,100,25,200,150,40,400);
37.   controll = ControllIO.getInstance(this);
38.   device = controll.getDevice("Logitech Cordless RumblePad 2");
39.   
40.   device.setTolerance(0.05f);
41.   
42.   
43.   ControllSlider sliderX = device.getSlider("Z-Achse");
44.   ControllSlider sliderY = device.getSlider("Z-Rotation");
45.   ControllSlider sliderX1 = device.getSlider("X-Achse");
46.   ControllSlider sliderY1 = device.getSlider("Y-Achse");
47.   
48.   stick = new ControllStick(sliderX,sliderY);
49.   stick1 = new ControllStick(sliderX1,sliderY1);
50. 
    
51.           // get right value for servo
52.   button = device.getButton("Taste 0");
53.   button1 = device.getButton("Taste 2");
54.  }
55. 
    
56. 
    
57. void draw()
58. {
59.   background(150);
60. 
    
61.   String n1;
62.   String n2;
63.   String sending;
64.   int speed = int(stick.getY()*-255+255); // get right value for motor controller
65.   int steer = int((stick1.getX()*45)+90);
66.   n1 = Integer.toString(steer);
67.   n2 = Integer.toString(speed);
68.   // if n1 or n2 is less than 4 digits add a zero to the front of them
69.   while (n1.length() < 4){
70.     n1 = '0' + n1;
71.   }
72.   while (n2.length() < 4){
73.     n2 = '0' + n2;
74.   }
75.   //combine the two 4 digit long strings into one 8 digit long one
76.   sending = n1 + n2;
77.   //write this to the serial port.
78.   myPort.write(sending);
79.   println(sending);
80.   controlP5.controller("Lenkung in %").setValue((steer-90)*2.5);
81.   controlP5.controller("Power in %").setValue(map(speed, 0, 510, -100, 100));
82.   fill(0);
83.   text("Sendestring: "+ sending, 800, 580);
84.   delay(20);
85. 
    
86. }