如何在toString中設置方法的結果

Question

我想在ToString中顯示方法的結果，該怎么辦？ 到目前為止，這是我的代碼：您可以在底行看到不知道寫什么才能獲取“ updatedPrice”的結果，您能幫上忙嗎？

        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";
    }

順便說一句 -我真的很陌生，完全是個開始。**謝謝。

Answer 1

只需在此處調用您的方法：

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";
}

---

注意：
通常，我建議在toString()方法中使用AGAINST調用方法。 如果只在toString()顯示類的狀態，因此僅顯示現有字段的值，那會更好。

---

因此，這意味着您應該引入一個名為finalPrice的字段並在其中存儲您的值。 之后，您可以使用toString()方法顯示此值：

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";
    }
  }

---

獎勵積分：
如果要比較字符串的內容，請不要使用==來比較字符串，而應使用equals() ！

Answer 2

創建屬性finalPrice並將值分配給

this.finalPrice = /*the price*/

並且您的代碼將正常工作

Answer 3

將finalPrice變量存儲為實例變量：

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";
    }

另一個提示：名稱變量始終以小寫字母開頭，這有助於您區分類名和變量名。