Imはdiscount.javaというクラスを書いて、私が述べたように、私は量と価格

Question

に負の値を処理の問題が生じています、私はdiscount.javaとTestDiscount.javaというクラスを書いています。これまでのすべてが動作しますが、実際の値の代わりにエラーメッセージを表示するのに問題があります。ここで必要な出力と私がこれまで行っているについて少し詳細情報は以下のとおりです。

出力は形式である必要があります。

量は次のとおりです。単価はあるXX：$ XX.XX割引です：$ XX.XX

それとも

量は次のとおりです。-XX数量がマイナスです。 $ 15.00お金負である、ことはできません 計算割引額

public class discount { 


    int quantity; 
    double price; 
    public static int NINETY_NINE = 99; 
    public static int TWENTY = 20; 
    private static int TEN = 10, FORTY_NINE = 49; 
    public static double TEN_PERCENT = 0.10, FIVE_PERCENT = 0.05, 
      TWO_PERCENT = 0.02, THREE_PERCENT = 0.03, ONE_PERCENT = 0.01 ; 
    private double discount; 
    // public static double discount_amount = discount * quantity * price; 


    discount(int quantity, double price) 
    { 
      double discount = 0; 
     //double d = discount; 
      this.quantity = quantity; 
      this.price = price; 
    } 
    boolean quantityOutOfRange() 
    { 
     return quantity < 0; 
    } 
    boolean priceOutOfRange() 
    { 
     return price < 0; 
    } 
    public double getDiscount() 
    { 
     return discount; 
    } 

    public int getQuantity() 
    { 
     return quantity; 
    } 

    public double getUnitPrice() 
    { 
     return price; 
    } 



    public void calculate() 
    { 
     if (quantity > NINETY_NINE) 
    { 
     if (price > TWENTY) 
       discount = TEN_PERCENT; 

     else if (price > TEN) 
       discount = FIVE_PERCENT; 
     else 
       discount = TWO_PERCENT; 
    } 
    else if (quantity > FORTY_NINE) 
    { 
    // calculate discount 
     if (price > TWENTY) 
       discount = THREE_PERCENT; 
     else if (price > TEN) 
       discount = TWO_PERCENT; 
     else 
       discount = ONE_PERCENT; 
    } 
    else 
    { 
    // calculate discount 
     if (price > TWENTY) 
       discount = TWO_PERCENT; 
     else if (price > TEN) 
       discount = ONE_PERCENT; 
     else 
       discount = 1; 
    } 
    if (quantity < 0) 
     { 
      System.out.println("Quantity is negative. Cannot compute discount"); 
     } 
    //double discount_amount = discount * quantity * price; 

    } 

} 



public class TestDiscount { 

    public static void main(String[] arg) { 

     String input = JOptionPane.showInputDialog("Enter the quantity desired " 
       + ", and unit price " 
       + "\n(Separated by spaces)"); 

     Scanner in = new Scanner(input); 

     int quantity = in.nextInt(); 
     double price = in.nextDouble(); 

     discount current = new discount(quantity, price); 
     current.calculate(); 
     System.out.println("\nDiscounts:\n"); 
     System.out.println("The quantity is: " + current.getQuantity()+ "\tThe unit price is = $ " + current.getUnitPrice() + 
       "\tThe discount is = $ " + current.getQuantity()* current.getUnitPrice() * current.getDiscount()); 
     System.exit(0) ; 
    } 
    } 

Answer 1

は

public boolean validated() { 

    boolean ok = true; 

    if (quantity < 0) 
    { 
     System.out.println("Quantity is negative. Cannot compute 
          discount"); 
     ok = false; 
    } 

    if (price< 0) 
    { 
     System.out.println("Price is negative. Cannot compute 
          discount"); 
     ok = false; 
    } 

    return ok; 

ようにと呼ばれる新しいメソッドを作成する - ：150単価は次のとおりです。数量は割引

それとも

を計算することができません

}

次にmain

discount current = new discount(quantity, price); 
if (current.validated()) { 
    current.calculate(); 
} 

Answer 2

方法で命名上の負の値

if (quantity < 0) 
{ 
    System.out.println("error message"); 
} 

if (price < 0) 
{ 
    System.out.println("error message"); 
}