Skip to content

lab6.md

Latest commit

 

History

History
160 lines (128 loc) · 6.93 KB

lab6.md

File metadata and controls

160 lines (128 loc) · 6.93 KB

Background

Learning objectives

  • Learn how to write classes
  • Learn how to use classes

Story

To write a program that controls one single drone is not hard. Some day, you will be the boss controlling 100 drones with a single line of code. Yet the road towards being a boss like that is hard. We can make it easier by letting you play with multiple fake drones before you get to actual drones.

Part 0: Fake Drone

(Name your project lab6-fake-drone)

You need three Java files: Main.java, FakeDrone.java, and FakeDroneSwarm.java. Let's discuss them in detail.

Main.java

We wrote this file for you! Just copy and paste it into your Main.java. Keep your package line untouched, of course!

package ...

public class Main
{
    public static void main(String[] args)
    {
        int n = Integer.parseInt(args[0]);
        FakeDroneSwarm swarm = new FakeDroneSwarm(n);
        System.out.println(swarm); // Don't forget this line
        swarm.takeoff();
        System.out.println(swarm);
        swarm.forward(100);
        System.out.println(swarm);
        swarm.turnLeft(120);
        System.out.println(swarm);
        swarm.forward(100);
        System.out.println(swarm);
        swarm.turnLeft(120);
        System.out.println(swarm);
        swarm.forward(100);
        System.out.println(swarm);
        swarm.turnLeft(120);
        System.out.println(swarm);
        swarm.land();
        System.out.println(swarm);
        System.exit(0);
    }
}

FakeDrone.java

Please follow the guide carefully.

  1. To create this file, right click of your Main.java file. Click New/Java Class.
  2. Type FakeDrone as the name.
  3. Hit enter.
  4. Now you should see a file with an empty class public class FakeDrone { }.
  5. Inside the class braces, you need to create the following:
    • Some class member variables to store the name (String) and flight status of the drone. (What's flight status? You will learn about it soon.) Q: Should these members be public or private?
    • A constructor that takes name (String) and initial position (double x, double y). Q: What should you write inside the contructor?
    • A method public String toString() { ... }. This method shall return a String saying which drone this is and where this is. Q: Should you call System.out.println here?
    • A method public void takeoff() { ... }. This method shall modify the flight status. If the drone has already taken off, don't do anything.
    • A method public void land() { ... }. This method shall modify the flight status. If the drone has not yet taken off, don't do anything.
    • A method public void turnLeft(double deg) { ... }. This method shall modify the flight status. If the drone has not yet taken off, don't modify the flight status **and print error message to System.err.
    • A method public void turnRight(double deg) { ... }. This method shall modify the flight status. If the drone has not yet taken off, don't modify the flight status **and print error message to System.err.
    • A method public void forward(double cm) { ... }. This method shall modify the flight status. If the drone has not yet taken off, don't modify the flight status **and print error message to System.err.
    • A method public void backward(double cm) { ... }. This method shall modify the flight status. If the drone has not yet taken off, don't modify the flight status **and print error message to System.err.

So what is flight status?

  • Has the drone taken off or not?
  • Where is (i.e., the coordinates of) the drone? (Note: You don't need to track the Z-axis position because we don't implement up and down!)
  • Which direction is the drone facing?

FakeDroneSwarm.java

Please follow the guide carefully.

  1. To create this file, right click of your Main.java file. Click New/Java Class.
  2. Type FakeDroneSwarm as name.
  3. Hit enter.
  4. Now you should see a file with an empty class public class FakeDroneSwarm { }.
  5. Inside the class braces, you need to create the following:
    • An array to store FakeDrones. Q: Should you initialize the array (like ... = new FakeDrone[...];) right there? If yes, how large the array should it be? If not, where else should you initialize it?
    • A constructor that takes number of fake drones (int). The (fake) drones should be named with the naming pattern, Drone #0, Drone #1, Drone #2, ... . The (fake) drones should be (virtually) placed at (0, 0), (100, 0), (200, 0), ... . Q: What should you write inside the contructor?
    • A method public String toString() { ... }. This method shall return a String summarizing the information of all of the fake drones. Q: Should you call System.out.println here?
    • A method public void takeoff() { ... }. This method shall command every fake drone to take off.
    • A method public void land() { ... }. This method shall command every fake drone to land.
    • A method public void turnLeft(double deg) { ... }. This method shall command every fake drone to turn.
    • A method public void turnRight(double deg) { ... }. This method shall command every fake drone to turn.
    • A method public void forward(double cm) { ... }. This method shall move every fake drone forward.
    • A method public void backward(double cm) { ... }. This method shall move every fake drone backward.

Testing

When you've finished coding, click the blue button and set the Arguments to 3. If everything is correct, you should see something similar to:

Drone #0 0.0 0.0 90.0 landed
Drone #1 100.0 0.0 90.0 landed
Drone #2 200.0 0.0 90.0 landed

Drone #0 0.0 0.0 90.0 flying
Drone #1 100.0 0.0 90.0 flying
Drone #2 200.0 0.0 90.0 flying

Drone #0 6.123233995736766E-15 100.0 90.0 flying
Drone #1 100.0 100.0 90.0 flying
Drone #2 200.0 100.0 90.0 flying

Drone #0 6.123233995736766E-15 100.0 210.0 flying
Drone #1 100.0 100.0 210.0 flying
Drone #2 200.0 100.0 210.0 flying

Drone #0 -86.60254037844386 49.999999999999986 210.0 flying
Drone #1 13.397459621556138 49.999999999999986 210.0 flying
Drone #2 113.39745962155614 49.999999999999986 210.0 flying

Drone #0 -86.60254037844386 49.999999999999986 330.0 flying
Drone #1 13.397459621556138 49.999999999999986 330.0 flying
Drone #2 113.39745962155614 49.999999999999986 330.0 flying

Drone #0 -2.8421709430404007E-14 -5.6843418860808015E-14 330.0 flying
Drone #1 99.99999999999997 -5.6843418860808015E-14 330.0 flying
Drone #2 199.99999999999997 -5.6843418860808015E-14 330.0 flying

Drone #0 -2.8421709430404007E-14 -5.6843418860808015E-14 450.0 flying
Drone #1 99.99999999999997 -5.6843418860808015E-14 450.0 flying
Drone #2 199.99999999999997 -5.6843418860808015E-14 450.0 flying

Drone #0 -2.8421709430404007E-14 -5.6843418860808015E-14 450.0 landed
Drone #1 99.99999999999997 -5.6843418860808015E-14 450.0 landed
Drone #2 199.99999999999997 -5.6843418860808015E-14 450.0 landed