1. IT Basic Wednesday 14 April 2010
27. august 2018
IT Basic
Wednesday 14 April
2010
Technical Faculty - Campus Horsens, Henrik Kronborg Pedersen –
Hanne Bundgaard

2. Agenda LeJOS and java elements Picking up blue or red balls
Technical Faculty - Campus Horsens, Henrik Kronborg Pedersen –

3. Don’t forget the steps….
Eclipse
New Java Project
New Class
Write the class
Save
Command Prompt
Go to project folder (workspace\project\src)
Compile the class (nxjc)
Link and upload (nxj)
Technical Faculty - Campus Horsens, Henrik Kronborg Pedersen –

4. The java class import lejos.nxt.*; public class HelloWorld {
Class file must be
named the same
( HelloWorld.java)
import lejos.nxt.*;
public class HelloWorld {
public static void main (String[] aArg) throws Exception
LCD.drawString("Hello World",3,4);
Thread.sleep(2000); }
Technical Faculty - Campus Horsens, Henrik Kronborg Pedersen –

5. The java class import lejos.nxt.*; public class HelloWorld {
To use LeJOS we must import the tools
This is where motors and sensors are defined
import lejos.nxt.*;
public class HelloWorld {
public static void main (String[] aArg) throws Exception
LCD.drawString("Hello World",3,4);
Thread.sleep(2000); }
Technical Faculty - Campus Horsens, Henrik Kronborg Pedersen –

6. The java class import lejos.nxt.*; public class HelloWorld {
public static void main (String[] aArg) throws Exception
LCD.drawString("Hello World",3,4);
Thread.sleep(2000); }
The main method must exist and is the starting method of your system
Just write it this way
Technical Faculty - Campus Horsens, Henrik Kronborg Pedersen –

7. The java class import lejos.nxt.*; public class HelloWorld {
Sometimes exception handling is required – then add the throws exception to your method
import lejos.nxt.*;
public class HelloWorld {
public static void main (String[] aArg) throws Exception
LCD.drawString("Hello World",3,4);
Thread.sleep(2000); }
Technical Faculty - Campus Horsens, Henrik Kronborg Pedersen –

8. The java class import lejos.nxt.*; public class HelloWorld {
public static void main (String[] aArg) throws Exception
LCD.drawString("Hello World",3,4);
Thread.sleep(2000); }
In methods we execute statements
Technical Faculty - Campus Horsens, Henrik Kronborg Pedersen –

9. For loop
import lejos.nxt.*; public class TenCount { public static void main (String[] aArg) throws Exception for(int count=1; count<11; count++) LCD.drawString("Count is: " + i, 3, 4); Thread.sleep(1000); }
Technical Faculty - Campus Horsens, Henrik Kronborg Pedersen –

10. while loop
int count = 1; while (count < 11) { LCD.drawString("Count is: " + count, 3, 4); count++; Thread.sleep(1000); } Google: java while
Count++
Is the same as
Count = count+1
Technical Faculty - Campus Horsens, Henrik Kronborg Pedersen –

11. If statement
if (bump.isPressed()) { right(); } else left(); Google: java if
Technical Faculty - Campus Horsens, Henrik Kronborg Pedersen –

12. FollowLine so far
import lejos.nxt.*; public class FollowLine { public static void main(String[] args) throws Exception LightSensor light = new LightSensor(SensorPort.S1); while (true) forward(); if (light.readValue() < 40) left(); } if (light.readValue() >= 40) right();
private static void forward() { Motor.A.forward(); Motor.C.forward(); } private static void left() throws Exception Motor.A.stop(); Thread.sleep(500); forward(); private static void right() throws Exception Motor.C.stop(); } //end class
Technical Faculty - Campus Horsens, Henrik Kronborg Pedersen –

13. Exercise 1
Count to 10
If a button is pressed before 10, count backwards
Technical Faculty - Campus Horsens, Henrik Kronborg Pedersen –

14. Exercise 2 Let your robot follow the line If it meets a red ball
Write: ”Found red ball” in the display
Pick it up
Turn to the right
Drop the ball
If a button is pressed, pick up blue balls instead
Technical Faculty - Campus Horsens, Henrik Kronborg Pedersen –