我如何获得要在 main 中使用的方法的值

如何解决我如何获得要在 main 中使用的方法的值

我对 Java 还是很陌生，我正在尝试编写一个程序，当我进行游戏内购买时，它会向我显示我的钱实际上为我带来了多少。 我正在努力从方法 convertYourself() 获取值到我的主要方法中，以便我可以将它们组合起来。 我想我很可能需要将它设为 double 而不是 void 并返回它，但是我将作为参数传递什么？ 谢谢！

public class TestCode {

    Scanner in = new Scanner(system.in);
    public static double gemValue = 0.01;
    public static double goldValue = 0.000004;
    
    public static void main(String[] args) {
        TestCode test = new TestCode();
        test.convertYourself(gemValue);
        test.convertYourself(goldValue);
        // double sum = how do i get the value of the convertYourself method so i can use it here?
        System.out.println("The total value of this bundle is :" + sum);
    }

    public void convertYourself(double x) {
        System.out.println("How many are you buying?");
        double currency = in.nextDouble();
        double convert = currency * x;
        System.out.println("The true value of this is: " + convert);
        

    }

}

解决方法

您需要有返回值的方法。可以这样做：

public double convertYourself(double x) {
    System.out.println("How many are you buying?");
    double currency = in.nextDouble();
    double convert = currency * x;

    return convert;
}

//To call it:
double valueReturned = convertYourself(gemValue);

因此，您必须将方法返回值从 void 更改为 double，并使用 return 关键字返回您想要的值。

,

对于方法，您可以使用返回类型而不是 void。 然后必须通过 return {value} 返回返回值。

//   return type
//      \/
public double convertYourself (double x) {
  double convert = /* convert */;
  return convert;
}

之后，您可以将输出存储在变量中：

double result = convertYourself (/* x */);

,

更具体的编码部分：

public class TestCode {

    Scanner in = new Scanner(System.in);
    public static double gemValue = 0.01;
    public static double goldValue = 0.000004;
    
    public static void main(String[] args) {
        // TestCode test = new TestCode(); ... you do not need this as the both methods are inside the same class. Make the convertYourself method as *static*. 
        double gemValueConverted = convertYourself(gemValue); // call it without the object 
        double goldValueConverted = convertYourself(goldValue);

        double sum = gemValueConverted + goldValueConverted;
        System.out.println("The total value of this bundle is :" + sum);
    }

    public static double convertYourself(double x) { // made the method static and added return type as double
        System.out.println("How many are you buying?");
        double currency = in.nextDouble();
        double convert = currency * x;
        System.out.println("The true value of this is: " + convert);
        return convert;
    }
}