一个返回double的int方法

Question

I've been trying to search online and look at books for this one but I can't find a solution. Everywhere I look with the return type int , the parameter variables also must be int , and the return variable also must be an integer . But my homework states that it must be an int method that returns a double .

So far here is what I have:

import java.util.Scanner;

public class ConvertF {

    public static void main(String args[]){

    int n =0;

    Scanner s = new Scanner(System.in);

    System.out.println("How many feet do you wish to convert to miles?");

    n = s.nextInt();

    System.out.println("Passing values to ConverToMiles");

    ConvertToMiles(422, 142);

    System.out.printf(feet + "feet equals %2.2n miles", miles);




}

    public static int ConvertToMiles(int feet, double miles){
        int answer;
        double f = (double)feet;
        answer = feet/5280;
        double a = (double)answer;
        return answer;




    }

}

Please help me out with a hint or a solution. Thanks a lot.

Answer 1

ALl you need to do is change

public static int ConvertToMiles(int feet, double miles){

to

public static double ConvertToMiles(int feet, double miles){

And then change the method so it's not converting to and from ints so much. When you do arithmetic with a double and an int, the return type of the expression is a double, unless you cast it.

Nothing mysterious, parameter types and return types have no relation to each other.

Answer 2

Ok so there are quite a few problems in this program. The code should look something along the lines of:

import java.util.Scanner;

public class ConvertF {

    public static void main(String args[]){

        Scanner s = new Scanner(System.in);

        System.out.println("How many feet do you wish to convert to miles?");

        //Grab the user's input and store in feet input
        int feetInput = s.nextInt();

        System.out.println("Passing values to ConverToMiles");

        //Store the value returned by convertToMiles in milesOutput
        double milesOutput = convertToMiles(feetInput);

        //This prints the output - note how I have used "%2.2f" as we are now working
        //with floats (or more precisely doubles)
        System.out.printf(feetInput + " feet equals %2.2f miles", milesOutput);
    }

    /*
     * The word after static is the type the method returns (in this case a double)
     * the parameter (int feet) has local scope to this method. This means that 
     * only this method can see the variable 'feet' - basically you cannot use feet 
     * in the main method above. You are not required to declare a 'miles' variable as
     * this is the value the method is returning, it can be stored in a variable where
     * the method is called
     */
    public static double convertToMiles(int feet){
        return feet/5280.0; //One of these values must be a double to return a double
    }

}

Please read the comments to gain a better insight into how things are working.

Also note how I have changed your method to convertToMiles instead of ConvertToMiles . This is just a java convention which helps make your code easier to read, especially when it grows in size.

Hope this helps, and happy coding :)

Answer 3

One solution of your question may be:

class Three
{
public static void main(String arg[])
{
int b=new Three().one();
System.out.println(b);
}
public  int one() 
{
double a=10;
return (int)a; 
}
}

Answer 4

要从“...但我的家庭作业声明它必须是一个返回双...的int方法”转换成Java，教师意味着：

 double methodName(int i)

Answer 5

The int method means, the return type of method will be int. The parameters can be any others.

As you have written: public static int ConvertToMiles(int feet, double miles) The first parameter will be the input and the second one, with type double will be the output. The return value only shows if the operation was succesfully or not. Only the inside of function needs to fill correctly.