title: Lesson 16 - Gas Mileage - Multiple Classes Project
body: <p>~~~Update: Solved! Thanks everyone!~~~
  <br/><br/>
  I'm working on a project from the Blue Pelican Java book, lesson 16 project Gas Mileage. It asks to create two classes, one is Automobile which holds the methods I will work with. The other class, Tester, is the main class. Every time I run the Tester class, it returns a value of -Infinity. I can't figure out why, other than that I've singled out the problem is in the Automobile class at line 14 in the takeTrip method. When I leave that method out of the Tester class, it returns the correct values.
  This is the Automobile class:</p>
  
  <pre><code>public class Automobile
  {
      public Automobile(double m) // Accepts value m to the double mpg. Also declares
      {
          double mpg = m;
          double gallons;
      }
      public void fillUp(double f) // Adds fuel to the tank
      {
          gallons += f;
      }
      public void takeTrip(double t) // Takes away fuel from the tank depending upon how many miles are driven
      {
          gallons -= t / mpg; // Not sure how to do this line. For some reason, when I reference mpg, the output of Tester is "-infinity". Shouldn't it do gallons = gallons - (miles driven / mpg)?
      }
      public double reportFuel() // Returns value of how much fuel is left in tank
      {
          double r = gallons;
          return r;
      }
      public double mpg;
      public double gallons;
  }
  </code></pre>
  
  <p><br/>And this is the Tester class:</p>
  
  <pre><code>public class Tester
  {
      public static void main(String args[])
      {
          Automobile myBmw = new Automobile(24); // Passes constructor argument of 24 mpg
          myBmw.fillUp(20); // Adds 20 gallons to fillUp method
          myBmw.takeTrip(100); // Takes away the fuel used for 100 miles using the takeTrip method
          double fuel_left = myBmw.reportFuel(); // Initializes fuel_left to the method reportFuel
          System.out.println(fuel_left);
      }
  }
  </code></pre>
  
  <p>Any help is appreciated, thanks!
  -AJ</p>