Added RaceWar2 which handles turns differently.

lesson8/RaceWar2.java

+import lejos.nxt.Button;
+import lejos.nxt.LCD;
+import lejos.nxt.LightSensor;
+import lejos.nxt.MotorPort;
+import lejos.nxt.SensorPort;
+import lejos.nxt.Sound;
+
+
+public class RaceWar2 {
+
+	static LightSensor left = new LightSensor(SensorPort.S1);
+	static LightSensor right = new LightSensor(SensorPort.S4);
+	static MotorPort motorLeft = MotorPort.B;
+	static MotorPort motorRight = MotorPort.C;
+
+	static int blackTreshold;
+	static int whiteTreshold;
+	static int blackWhiteTreshold;
+
+	static int command = 0; // 0 = left, 1 = right, 2 = u-turn, 3 = finish
+	static int power = 70;
+
+	public static void main(String[] args) throws InterruptedException {
+		calibrate();
+
+		LCD.clear();
+		while( !Button.ENTER.isDown() ){
+			LCD.drawString("Start", 0, 0);
+		}
+
+		motorRight.controlMotor(power, MotorPort.BACKWARD);
+		motorLeft.controlMotor(power - 5, MotorPort.BACKWARD);
+		int times = 0;		
+		double firstCornerTime = Double.POSITIVE_INFINITY;				
+		
+		LCD.drawString("left: ", 0, 1);
+		LCD.drawString("right: ", 0, 2);
+		LCD.drawString("taco: ", 0, 3);		
+
+		while(true) {
+			int leftV = left.readValue();
+			int rightV = right.readValue();
+			LCD.drawInt(command, 0, 0);
+			LCD.drawInt(leftV, 4, 10, 1);
+			LCD.drawInt(rightV, 4, 10, 2);
+			if(command == 0) {
+				if (rightV <= blackTreshold + 5) {
+					motorRight.controlMotor(power, MotorPort.FORWARD);
+					motorLeft.controlMotor(power, MotorPort.BACKWARD);
+					Sound.beep();
+					firstCornerTime = System.currentTimeMillis();
+				}
+				else if (rightV < blackWhiteTreshold + 3) {
+					motorRight.controlMotor(power, MotorPort.FORWARD);
+					motorLeft.controlMotor(power, MotorPort.BACKWARD);
+				} else {
+					motorRight.controlMotor(power, MotorPort.BACKWARD);
+					motorLeft.controlMotor(power - 5, MotorPort.BACKWARD);
+				}
+				
+				if(System.currentTimeMillis() >  firstCornerTime + 3000) {					
+					command = 1;
+					Sound.beepSequence();
+				}
+			} else if(command == 1) {
+				if(times > 200) {
+					times = 0;
+					command = 2;
+					Sound.beep();
+				}
+				if(rightV <= blackTreshold + 3 && leftV <= blackTreshold + 3) {
+					times++;
+					motorLeft.controlMotor(power, MotorPort.BACKWARD);
+					motorRight.controlMotor(power, MotorPort.BACKWARD);
+					continue;
+				}
+				
+				if(leftV < blackWhiteTreshold) {
+					motorLeft.controlMotor(power, MotorPort.FORWARD);
+					motorRight.controlMotor(power, MotorPort.BACKWARD);
+				} else {
+					motorLeft.controlMotor(power, MotorPort.BACKWARD);
+					motorRight.controlMotor(power - 5, MotorPort.BACKWARD);
+				}
+				
+			} else if(command == 2) {
+				motorLeft.resetTachoCount();
+				motorRight.resetTachoCount();
+				while(motorRight.getTachoCount() * -1 < 360) {
+					LCD.drawInt(motorRight.getTachoCount(), 0, 3);
+					motorLeft.controlMotor(power, MotorPort.BACKWARD);
+					motorRight.controlMotor(power, MotorPort.BACKWARD);
+				}
+				motorRight.resetTachoCount();
+				while(motorRight.getTachoCount() * -1 < 200) {
+					motorLeft.controlMotor(power, MotorPort.FORWARD);
+					motorRight.controlMotor(power, MotorPort.BACKWARD);
+				}
+
+				motorRight.resetTachoCount();
+				while(motorRight.getTachoCount() * -1 < 360) {
+					motorLeft.controlMotor(power, MotorPort.BACKWARD);
+					motorRight.controlMotor(power, MotorPort.BACKWARD);
+				}
+
+				command = 3;
+				Sound.beep();
+			} else if(command == 3) {
+				power = 60;
+				if(rightV > blackWhiteTreshold + 10) {
+					motorLeft.controlMotor(power-10, MotorPort.BACKWARD);
+					motorRight.controlMotor(power+10, MotorPort.BACKWARD);
+				} else if (rightV > blackTreshold + 10)  {					
+					motorLeft.controlMotor(power+5, MotorPort.BACKWARD);
+					motorRight.controlMotor(power-5, MotorPort.BACKWARD);
+				} else {
+					motorRight.controlMotor(power, MotorPort.FORWARD);
+					motorLeft.controlMotor(power, MotorPort.BACKWARD);
+				}
+			} 
+		}
+	}
+
+	public static void calibrate() {
+		// black
+		int leftV;
+		int rightV;
+
+		rightV = right.readValue();
+		while( !Button.ENTER.isDown() ){
+			leftV = left.readValue();
+			rightV = right.readValue();
+			blackTreshold = (leftV + rightV) / 2;
+			LCD.drawString("Calibrate black", 0, 0);
+			LCD.drawInt(blackTreshold, 4, 10, 2);
+		}
+		while( Button.ENTER.isDown() ){}
+
+		// white
+		while( !Button.ENTER.isDown() ){
+			leftV = left.readValue();
+			rightV = right.readValue();
+			whiteTreshold = (leftV + rightV) / 2;
+			LCD.drawString("Calibrate white", 0, 0);
+			LCD.drawInt(whiteTreshold, 4, 10, 2);
+		}
+		while( Button.ENTER.isDown() ){}
+		blackWhiteTreshold = (blackTreshold + whiteTreshold) / 2;
+	}
+
+}