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java - 如何将 Scanner.in 值从方法返回到另一个方法

问题描述

我想做一些简单的程序来计算产品的月费率。有两个输入：产品成本 - 100-10000 和费率数量 - 6-48。我想像下面的代码那样做：

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);
}
}
}

而主方法只调用其他类的方法。

public class MonthlyRate {
public static void main(String[] args) {
    Calculator calc = new Calculator();
    calc.print();
    // TODO code application logic here
}

}

有什么问题，我不知道如何从方法“print（）”返回“double productCost”。productCost 是从输入中获取的，这是双倍的，但 NetBeans 向我显示它不是正确的类型。谁能帮我理解问题出在哪里？

标签： javareturn

解决方案

简单地做

    return productCost;

return是关键字，而不是变量。它“返回”给定值并退出函数，以便调用函数的实体可以执行以下操作：

public static void main(String[] args) {
    ...
    double cost = calc.print();  // note calc.print() PRODUCES a value, which we assign to `cost`
    ...
}

然后你可以做任何你想做的事情cost（或者你选择命名变量的任何东西），包括将它传递给另一个函数。

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