如何在toString中设置方法的结果

Question

I want to display the result of a method in my ToString, how can I do that? here is my code so far: you can see at the bottom line that I don't know what to write for getting the result of the "updatedPrice", can u help?

        public double updatedPrice(double price){
        this.price=price;

        double ChangePriceRate, ChangePriceAmount, finalPrice;

        if(name=="Bamba"){
            ChangePriceRate = 0.15;
        }else{
            ChangePriceRate = 0.05;
        }

        ChangePriceAmount = price * ChangePriceRate;

        if(name=="Bamba"){
            finalPrice = price + ChangePriceAmount;
        }else{

            finalPrice = price - ChangePriceAmount;
    }




    }

    public String toString (){

        return  "Name of the Snack: "+name+ "\n"+
                "Name of the Company: "+comp+ "\n"+
                "Price before discount: "+this.price+ "\n"+
                "Price after discount: "+        **finalPrice?**      + "\n";
    }

btw - I'm really new to this, a total begginer.** thank you.

Answer 1

Just call your method there:

public String toString (){
    return  "Name of the Snack: " + name + "\n" +
            "Name of the Company: " + comp + "\n" +
            "Price before discount: " + this.price+ "\n" +
            "Price after discount: " + updatedPrice(this.price) + "\n";
}

---

Attention:
Generally I would advise AGAINST calling methods in the toString() method. It would be better if you only show the state of the class inside toString() and therefore only show the values of existing fields.

---

This means in consequence that you should introduce a field called finalPrice and store your value there. After that you can show this value using the toString() method:

public static class MyClass {

    private String name;
    private String comp;
    private double price;
    private double finalPrice; // <-- Field for final price

    [...]    

    public void updatePrice(double price) {
      this.price = price;

      double changePriceRate;
      double changePriceAmount;

      if ("Bamba".equals(this.name)) { // <-- Use equals()!
        changePriceRate = 0.15;
      } else {
        changePriceRate = 0.05;
      }

      changePriceAmount = price * changePriceRate;

      if ("Bamba".equals(this.name)) { // <-- Use equals()!
        finalPrice = price + changePriceAmount;
      } else {
        finalPrice = price - changePriceAmount;
      }
    }

    public String toString() {
      return "Name of the Snack: " + name + "\n" +
             "Name of the Company: " + comp + "\n" +
             "Price before discount: " + price + "\n" +
             "Price after discount: " + finalPrice + "\n";
    }
  }

---

Bonus point:
Do not use == for comparing strings, use equals() instead if you want to compare the contents of strings!

Answer 2

create a property finalPrice and assign the value to

this.finalPrice = /*the price*/

and your code will work

Answer 3

store the finalPrice variable as an instance variable:

double finalPrice;

    public double updatedPrice(double price){
        this.price=price;

        double ChangePriceRate, ChangePriceAmount;

        if(name=="Bamba"){
            ChangePriceRate = 0.15;
        }else{
            ChangePriceRate = 0.05;
        }

        ChangePriceAmount = price * ChangePriceRate;

        if(name=="Bamba"){
            finalPrice = price + ChangePriceAmount;
        }else{

            finalPrice = price - ChangePriceAmount;
        }
        return finalPrice;
    }

    public String toString (){

        return  "Name of the Snack: "+name+ "\n"+
                "Name of the Company: "+comp+ "\n"+
                "Price before discount: "+this.price+ "\n"+
                "Price after discount: "+        finalPrice      + "\n";
    }

and another hint: name variables always with a lowercase letter at the beginning, it helps you to differentiate between class names and variable names.