Vehicle.java

class Vehicle {  //represents a vehicle that moves between 20 and -20, to illustrate OOP 
  public int location;
  
  public Vehicle() {
    location = 0;
  }
  
  public Vehicle(int loc){
    if(loc <= 20 && loc >= -20){
      location = loc;
    } else {
      location = 0;
    }
  }
 
 public void forward() {
    if(location < 20) {
      location++;
    }
  }
  
  public void backward() {
    if(location > -20) {
      location--;
    }
  }
  
  public int getLocation() {
    return location;
  }
  
  public String toString() {
    StringBuilder string = new StringBuilder();
    for(int i = -20; i < location; i++) {
      string.append(" ");
    }
    string.append("@");
    return string.toString();
  }