我想制作一些簡單的程序來計算產品的月費率。有兩個輸入：產品成本 - 100-10000 之間和費率數量 - 6-48 之間。我想像下面的代碼那樣做到這一點：import java.util.Scanner;public class Calculator {Scanner sc = new Scanner (System.in);double productCost;int numberOfRates;double loanInterestRate;double monthlyRate;Double print () {Calculator c = new Calculator();System.out.println ("Enter the value of your product from 100 to 10 000 : ");productCost=sc.nextDouble();if (productCost < 100){ System.out.println ("You have to choose price between 100 to 10000. Try again: "); c.print();} else if (productCost >10000){ System.out.println ("You have to choose price between 100 to 10000. Try again: "); c.print();} else if (productCost >= 100 || productCost <=10000){ c.print1(); return = productCost; // how to return productCost to be used in next method print1()?}else return null; }void print1(){Calculator c = new Calculator(); System.out.println ("Now enter how many rates do you want to pay from 6 to 48: ");numberOfRates=sc.nextInt();if (numberOfRates<6){ System.out.println ("You can't choose this number of rates. Choose between 6-48: "); c.print1();} else if (numberOfRates>48){ System.out.println ("You can't choose this number of rates. Choose between 6-48: "); c.print1();} else if (numberOfRates>=6 || numberOfRates<=12) { loanInterestRate=1.025; monthlyRate = (productCost*loanInterestRate)/numberOfRates; System.out.printf("Your monthly rate is: "+ "%.2f%n",monthlyRate);} else if (numberOfRates>=13 || numberOfRates <=24 ) { loanInterestRate=1.05; monthlyRate = (productCost*loanInterestRate)/numberOfRates; System.out.printf("Your monthly rate is: "+ "%.2f%n",monthlyRate);} else if (numberOfRates >=25|| numberOfRates<=48){ loanInterestRate=1.1; monthlyRate = (productCost*loanInterestRate)/numberOfRates; System.out.printf("Your monthly rate is: "+ "%.2f%n",monthlyRate);}}}問題是什么，我不知道如何從方法“print()”返回“雙倍productCost”。ProductCost 是從輸入中獲取的，這是雙倍的，但 NetBeans 向我表明它不是正確的類型。有人能幫我理解問題出在哪里嗎？
2 回答
收到一只叮咚
TA貢獻1821條經驗 獲得超5個贊
簡單地做
return productCost;
return是關鍵字，而不是變量。它“返回”給定值并退出函數，以便調用該函數的實體可以執行以下操作：
public static void main(String[] args) {
...
double cost = calc.print(); // note calc.print() PRODUCES a value, which we assign to `cost`
...
}
然后，您可以執行任何您想要的操作cost（或任何您選擇的變量命名方式），包括將其傳遞給另一個函數。
滄海一幻覺
TA貢獻1824條經驗 獲得超5個贊
您的程序需要在一些地方進行更改。我已經完成了這些更改并寫在更新后的程序下面：
import java.util.Scanner;
class Calculator {
Scanner sc = new Scanner(System.in);
double productCost;
int numberOfRates;
double loanInterestRate;
double monthlyRate;
void print() {
Calculator c = new Calculator();
System.out.println("Enter the value of your product from 100 to 10 000 : ");
productCost = sc.nextDouble();
if (productCost < 100) {
System.out.println("You have to choose price between 100 to 10000. Try again: ");
c.print();
} else if (productCost > 10000) {
System.out.println("You have to choose price between 100 to 10000. Try again: ");
c.print();
} else if (productCost >= 100 || productCost <= 10000) {
print1(productCost);
}
}
void print1(double productCost) {
Calculator c = new Calculator();
System.out.println("Now enter how many rates do you want to pay from 6 to 48: ");
numberOfRates = sc.nextInt();
if (numberOfRates < 6) {
System.out.println("You can't choose this number of rates. Choose between 6-48: ");
c.print1(productCost);
} else if (numberOfRates > 48) {
System.out.println("You can't choose this number of rates. Choose between 6-48: ");
c.print1(productCost);
} else if (numberOfRates >= 6 || numberOfRates <= 12) {
loanInterestRate = 1.025;
monthlyRate = (productCost * loanInterestRate) / numberOfRates;
System.out.printf("Your monthly rate is: " + "%.2f%n", monthlyRate);
} else if (numberOfRates >= 13 || numberOfRates <= 24) {
loanInterestRate = 1.05;
monthlyRate = (productCost * loanInterestRate) / numberOfRates;
System.out.printf("Your monthly rate is: " + "%.2f%n", monthlyRate);
} else if (numberOfRates >= 25 || numberOfRates <= 48) {
loanInterestRate = 1.1;
monthlyRate = (productCost * loanInterestRate) / numberOfRates;
System.out.printf("Your monthly rate is: " + "%.2f%n", monthlyRate);
}
}
}
public class MonthlyRate {
public static void main(String[] args) {
Calculator calc = new Calculator();
calc.print();
// TODO code application logic here
}
}
將您的程序與此更新的程序進行比較后，很容易理解這些變化。盡管如此，如果您需要任何進一步的幫助，請隨時告訴我。
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