Thread: Problem with School Assignment.

n/a

it keeps putting an error on my "=" sign, for the line Ship myShip = new Ship();

You're getting an error on this line because you haven't defined a constructor with no arguments. By default and for each class you make, Java makes a constructor that takes no arguments. However, when you define a constructor with arguments in your class, the default constructor is no longer created (such as in your Ship class). In your Ship class, the only valid constructor is one that takes two arguments. So, to fix this, you could either create a second constructor in your Ship class or fix your line of code:

Ship myShip = new Ship();

so that when you call the Ship() constructor you put in arguments.

No, no, no; not on your ShipTest class, in your Ship class. The only constructor that you have in your Ship class is one that takes two arguments, but you want to create a new Ship with no arguments. To do this, you have to create a constructor in your Ship class that has no arguments listed in it.

Hahahaha, thank you! I'm gathering that it works? ;D

By the way, sorry for the slow response; Minecraft is rather addicting.

Haha! Minecraft is pretty awesome.

So... Your problem is with the timeToCrossEnglishChannel() method. First of all, unless I'm mistaken, the PDF you provided said that this method won't take any arguments (which makes sense, because the Ship object stores the information for speed).

I don't remember the formula, but your PDF provided a conversion from knots to mph. Then, you'll need a little math:

rate = distance / time

If we rearrange that to solve for time (which we don't know; we do know distance -- 21 miles -- and rate -- the speed of the Ship object), we get this:

time = distance / rate

So, you need to convert your speed to mph, then divide the distance through the channel by the speed of the Ship.

As for you set methods, I don't see any issue. The return type you have coded is void, which is correct (set method's don't return anything, just set a value of an object's field). What is the problem?

[EDIT: I'm going to sleep for tonight. I'll check the thread tomorrow and offer more help if you still need it. Good luck!]

No, you don't need to do that. Speed is a private variable of Ship, which means only the Ship class can directly access it (that's why we need getters and setters, so other classes can still call the values of a Ship object). This also means that ANY method in your ship class can reference speed simply by you typing "speed," as you did in your getSpeed and setSpeed methods.

For example, look at this quick class

public class Numbers
{
 
   private int numA;
   private int numB; //private, only THIS class can directly reference them
 
   //constructors, getters, setters; you know what they look like :P
 
   //Here's an example of a non-getter-setter method
   //like your English Channel method
 
   public int getSum()
   {
 
      return (numA + numB);
      //Note, I can still just directly use "numA" and "numB"
      //without any special set or get calls
 
   }
}

Hopefully that makes things a little more clear?