java - Java 中的返回类型(请批评)

Question

鉴于我的下面的程序，我对返回行在方法中实际执行的操作有点困惑。无论我在那里放置什么变量，当我在主类中调用该方法时，它仍然返回相同的值。在非 void 的方法中使用 return(变量名)到底有什么作用？您是否应该在方法头中列出每个变量的返回语句？抱歉，我只是想真正理解方法。另外，您能批评一下我的整体计划吗？是否有意义？看起来写得不错吗？谢谢!

    import java.util.Scanner;


public class Calculator {

    public static void main(String[] args) {


        int seconds=0, minutes=0, hours=0, days=0;

        System.out.println("We will convert seconds to minutes hours and days!");
        System.out.println("How many conversions would you like to do?");
        Scanner keyboard = new Scanner(System.in);
        int conversion =keyboard.nextInt();
        for (int count = 1; count <= conversion; count++)
        {
                Calculator.convert();
        }
    }
    public static void convert()
        {
            System.out.println("Enter seconds: ");
            Scanner keyboard = new Scanner(System.in);
            double seconds, minutes, hours, days;
            seconds = keyboard.nextInt();
            minutes = seconds/60.0;
            hours = minutes/60.0;
            days = hours/24.0;
            System.out.println("Minutes: " + minutes + " Hours: " + hours + " Days: " + days);


        }


}

Answer 1

您不需要在方法中使用 return，因为您不使用它。返回用于将值返回给调用函数的程序。例如，如果您想返回“天”值，您应该调用如下方法:

double days = Calculator.convert(seconds, minutes, hours, days);

但是，如果您不需要在程序中返回该方法生成的值，则您的方法应该不返回任何内容。关键字“void”没有指定任何内容。例如:

public static void convert(double seconds, double minutes, double hours, double days)
        {
            System.out.println("Enter seconds: ");
            Scanner keyboard = new Scanner(System.in);
            seconds = keyboard.nextInt();
            minutes = seconds/60.0;
            hours = minutes/60.0;
            days = hours/24.0;
            System.out.println("Minutes: " + minutes + " Hours: " + hours + " Days: " + days);
        }