import java.io.*;

public class RetailPrice
{
    public static void main(String [] args) throws IOException
    {
        String input;
        double ws;
        int mup;
        double retail;
        retail = ws * mup;
        
        //create objects for keyboard entry.
        InputStreamReader reader = new InputStreamReader(System.in);
        BufferedReader keyboard = new BufferedReader(reader);
        
        System.out.println("This program displays an item's retail price based on wholesale and markup input entered by user");
        
        //get wholesale cost.
        System.out.print("What is wholesale cost? ");
        input = keyboard.readLine();
        ws = Double.parseDouble(input);
        
        
        //get markup %.
        System.out.print("What is markup? ");
        input = keyboard.readLine();
        mup = Integer.parseInt(input);
        
        if (ws > 0 && mup > 0)
            calcRetail();
        else
            invalidEntry();
        
        System.out.println("Tootles.");
        
    
            }
            public static void calcRetail()
            {
            System.out.println("Retail is: " + retail);
            }
            
            public static void invalidEntry()
            {
            System.out.println("your entry is invalid.");
            }
    }

public static void calcRetail(retail)

The declaration inside a class for the method would be :

public static void calcRetail(double retail){

     //code for this method comes here

}
//The method call inside your main would be

calcRetail(retail); //if something is returned, you can store it inside a variable of data-type same as the return type.
//if the return type is void, i.e. you are not returning anything. You can simply call it like the above statement.

System.out.println("Hi.");
if (ws > 0 && mup > 0)
calcRetail(retail);
else
invalidEntry();

public static void calcRetail(double retail)
{
System.out.println("Retail is: " + retail);
}

public static void invalidEntry()
{
System.out.println("your entry is invalid.");
}
}

import java.io.*;

public class RetailPrice
{
public static void main(String [] args) throws IOException
{
String input;
double ws;
int mup;
double retail;
retail = ws * mup;

//create objects for keyboard entry.
InputStreamReader reader = new InputStreamReader(System.in);
BufferedReader keyboard = new BufferedReader(reader);

System.out.println("This program displays an item's retail price based on wholesale and markup input entered by user");

//get wholesale cost.
System.out.print("What is wholesale cost? ");
input = keyboard.readLine();
ws = Double.parseDouble(input);


//get markup %.
System.out.print("What is markup? ");
input = keyboard.readLine();
mup = Integer.parseInt(input);
retail = ws * mup;

System.out.println("For wholesale and markup% entered,");
calcRetail(retail);

}
public static void calcRetail(double retail)
{
System.out.println("Retail is: " + retail);
}
}