从子类Java获取值

Question

I am making a computer pricing program in Java. I am trying to figure out a way to generate subclasses determined by the user output. Heres my code so far. I realize I am running the same methods multiple times but I dont know any other way to get the variable in order to test the output. For some reason when the b.getScreenPrice(screenPrice) isn't executed when 2 is picked. Any answers if of help. thanks

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Computer {
    InputStreamReader in = new InputStreamReader(System.in);

    BufferedReader keyboard = new BufferedReader(in);

    public Computer() {

    }

    public String pickComputer() {
        String comp = null;
        System.out.println("Select a number for desired computer:");
        System.out.println("1. Desktop");
        System.out.println("2. Laptop");
        try {
            comp = keyboard.readLine();
            if (comp.equals("1")) {
                comp = "Desktop";
            }
            if (comp.equals("2")) {
                comp = "Laptop";
            }
        } catch (IOException e) {
            pickComputer();
        }
        return comp;
    }

    public class Notebook extends Computer {
        public String getScreenSize() {
            String size = null;
            System.out.println("Select a number for the desired screen size:");
            System.out.println("1. 19 inch ($200)");
            System.out.println("2. 17 inch ($150)");
            System.out.println("3. 15 inch ($100)");
            try {
                size = keyboard.readLine();

                if (size.equals("1")) {
                    size = "19";
                }
                if (size.equals("2")) {
                    size = "17";
                }
                if (size.equals("3")) {
                    size = "15";
                }

            } catch (IOException e) {
                getScreenSize();
            }
            return size;

        }

        public int getScreenPrice(String screen) {
            int sPrice = 0;
            if (screen.equals("19")) {
                sPrice = 200;
            }
            if (screen.equals("17")) {
                sPrice = 150;
            }
            if (screen.equals("15")) {
                sPrice = 100;
            }
            return sPrice;

        }

        public void calculatePrice(int screeen) {
            System.out.println(screeen);
        }

    }

    public class ComputerTester {
        public static void main(String[] args) {

            Computer a = new Computer();
            Notebook b = new Notebook();
            String screenSize = b.getScreenSize();
            String newComputer = a.pickComputer();

            if (newComputer.equals("Desktop")) {
                System.out.println("Test Worked");
            }
            if (newComputer.equals("Laptop")) {
                b.getScreenPrice(screenSize);
            }
        }
    }
}

Output:

Select a number for the desired screen size:
1. 19 inch ($200)
2. 17 inch ($150)
3. 15 inch ($100)
1
Select a number for desired computer:
1. Desktop
2. Laptop
2

Answer 1

Try changing your code to use

size = keyboard.readLine().trim();

This will trim any trailing and leading whitespace. If you were print out your size, I bet it would have a new line character on the end of it cause by pressing enter.

Answer 2

In your getScreenPrice(String) method, you are returning an int value but in your main method you are just calling the method. You are not setting an int value or anything. So what is happening is your code is working fine if nothing happens when you choose 2 because at the end of your program "nothing" is suppose to happen.

Try changing this:

        if (newComputer.equals("Laptop")) {
            b.getScreenPrice(screenSize);
        }

in this:

        if (newComputer.equals("Laptop")) {
           int price = b.getScreenPrice(screenSize);
           System.out.println(price.toString());
        }

I think what youre looking for will appear