How do I use another method in a method?

Question

I want to use the method preisProKilo() in the method gesamtpreis() ? Its about calculating the total price of a product. preis pro kilo = price per kilo and gesamtpreis = total amount .

class Kaffeeladen {

  double preisProKilo(double grundpreis) {        
        return (grundpreis + 2.19) * 1.19;
  }

  double gesamtpreis(int gewuenschteMenge, double preisProKilo) {      
    return preisProKilo * gewuenschteMenge; 
    //Here its not using the method "preisProKilo" from above. 
  }

  public static void main(String[] args) {
    Kaffeeladen k = new Kaffeeladen();

    double preis1 = k.preisProKilo(3.00);
    System.out.println("Bei einem Grundpreis von 3,00 Euro kostet 1 kg Kaffee inklusive Steuern " + preis1 + " Euro.");


  }
}

Answer 1

You are getting confused because you named the method and variable the same thing. Don't do this.

You are not calling a method at all, you are only using the variable.

It should be something like this:

double preisProKilo(double grundpreis) {
    return (grundpreis + 2.19) * 1.19;
}

double gesamtpreis(int gewuenschteMenge, double newValueName) {
    return preisProKilo(newValueName) * gewuenschteMenge; 
}

You can change the name of newValueName to whatever you choose, just please try to use different names.

Additionally, I do not see anywhere you are actually using gesamtpreis(int, double) , so you would need to use this as well by doing in your main something like this:

Kaffeeladen k = new Kaffeeladen();
double value = k.gesamtpreis(2, 3.00);

Answer 2

You probably wanted to give gewuenschteMenge that is the desired quantity and grundpreis that is the basic price in your gesamtpreis or full price method.

class Kaffeeladen {

  double preisProKilo(double grundpreis) {        
        return (grundpreis + 2.19) * 1.19;
  }

  double gesamtpreis(int gewuenschteMenge, double grundpreis) {      
    return preisProKilo(grundpreis) * gewuenschteMenge; 
  }

  public static void main(String[] args) {
    Kaffeeladen k = new Kaffeeladen();

    double preis1 = k.preisProKilo(3.00);
    System.out.println("Bei einem Grundpreis von 3,00 Euro kostet 1 kg Kaffee inklusive Steuern " + preis1 + " Euro.");


  }
}

You are actually using preisProKilo variable over calling the method preisProKilo(double grundpreis) to do so you have to call it as shown in the code above.

Answer 3

I'm not sure exactly what you're trying to do here, as the naming of variables is the same as the method names, but to call a method, you need to use the syntax methodToCall(arg1, arg2) .

It seems you have a lack of understanding of how methods work. One way to think of it is in terms of math functions. For example,

f(x)= x + 1

If x is 1, f(x) has a value of 2. If x is 2, f(x) has a value of 3, and so on.

So the same way to write that in Java would be as follows:

public int addOne(int x) {
  return x + 1;
}

And to call that method, you'd do this.

public int doWork(int value) {
  // doing work...
  value = addOne(value);
  // doing more work...
  return value;
}