Using the this reference in class Ship3

/./././././././././.
// Give Ship3 a constructor to let the instance variables
// be specified when the object is created.
/./././././././././

class Ship3 {
  public double x, y, speed, direction;
  public String name;

  public Ship3(double x, double y, double speed,
               double direction, String name) {
    this.x = x; // "this" differentiates instance vars
    this.y = y; //  from local vars.
    this.speed = speed;
    this.direction = direction;
    this.name = name;
  }
  
  private double degreesToRadians(double degrees) {
    return(degrees * Math.PI / 180.0);
  }

 public void move() {
    double angle = degreesToRadians(direction);
    x = x + speed * Math.cos(angle);
    y = y + speed * Math.sin(angle);
  }

  public void printLocation() {
    System.out.println(name + " is at " + 
                       "(" + x + "," + y + ").");
  }
}

public class Test3 {
  public static void main(String[] args) {
    Ship3 s1 = new Ship3(0.0, 0.0, 1.0,   0.0, "Ship1");
    Ship3 s2 = new Ship3(0.0, 0.0, 2.0, 135.0, "Ship2");
    s1.move();
    s2.move();
    s1.printLocation();
    s2.printLocation();
  }
}