методы классы и объекты

Question

Я не знаю, в чем моя ошибка, я не понимаю классы

Я прочитал книгу по Java, но ее бесполезные коды и методы классов смущают меня, и хотя вы выясняете мой код, у меня будетлучшее понимание того, что на самом деле делают эти вещи

public double intoxicated(double weight)
     {
         double numDrinks;

         numDrinks = (0.08 + 0.015) * weight / 
                  (12 * 7.5 * alcohol);
         return numDrinks;
     }


public class Beer
{
   private String name; 
   private double alcohol; 

   public String getName(){
       return name;
   }

   public void setName(String n)
   {
       this.name= name;

   }

   public double getAlcohol()
   {
       return Alcohol;

   }

   public void setAlcohol(double a)
   {
      this.age = age;

   }

   public double intoxicated(double weight)
    {
    double numDrinks;

    numDrinks = (0.08 + 0.015) * weight /
            (12 * 7.5 * alcohol);
    return numDrinks;
    }

   public static void main(String[] args)
   {
       Beer beer1 = new Beer();
       Beer beer2 = new Beer();


       beer1.setName("Cors Light");
       beer1.setAlcohol(0.042); 
       beer2.setName("Heinaken");
       beer2.setAlcohol(0.042); 

       double lightWeight = 100.0;
       double heavyWeight = 250.0; 

       double lightDrinks1 = beer1.intoxicated(lightWeight);
       System.out.println("The number of " + beer1.getName() +
               " drinks needed to make\na person weighing " +
               lightWeight + " pounds intoxicated is " + lightDrinks1);
       System.out.println();



   double heavyDrinks1 = beer1.intoxicated(heavyWeight);
   System.out.println("The number of " + beer1.getName() +
           " drinks needed to make\na person weighing " +
           heavyWeight + " pounds intoxicated is " + heavyDrinks1);
   System.out.println();


      double lightDrinks2 = beer2.intoxicated(lightWeight);
      System.out.println("The number of " + beer2.getName() +
               " drinks needed to make\na person weighing " +
               lightWeight + " pounds intoxicated is " + lightDrinks2);
       System.out.println();


       double heavyDrinks2 = beer2.intoxicated(heavyWeight);
       System.out.println("The number of " + beer2.getName() +
               " drinks needed to make\na person weighing " +
               heavyWeight + " pounds intoxicated is " + heavyDrinks2);
       System.out.println();


       Beer beer3 = new Beer();
       beer3.setName("Miller Genuine Draft Light");
       beer3.setAlcohol(0.042); // 4.2% alcohol

       lightWeight = 100.0; 
       heavyWeight = 250.0; 

       double lightDrinks3 = beer3.intoxicated(lightWeight);
       System.out.println("The number of " + beer3.getName() +
               " drinks needed to make\na person weighing " +
               lightWeight + " pounds intoxicated is " + lightDrinks3);
       System.out.println();

       double heavyDrinks3 = beer3.intoxicated(heavyWeight);
       System.out.println("The number of " + beer3.getName() +
               " drinks needed to make\na person weighing " +
               heavyWeight + " pounds intoxicated is " + heavyDrinks3);
       System.out.println();
   }
}