我将如何创建输入命令来执行代码的不同部分？ -Java

Question

I have created a basic java program that determines the hypotenuse of a triangle. Originally, the program would ask for side A, then side B, and automatically calculate the hypotenuse.

I want to create a input command list that will allow the user to type "a" in when giving the A side value, type "b" when giving the B side value, and then type "c" to calculate the hypotenuse, or "q" to exit the program.

Instead of forcing the user to put in side A first, I want them to be able to put in either side at there will. However, if the user types "c" and either the A or B value is missing (or both) I would like an error message and have the user correct it.

So far I have

import java.util.InputMismatchException;
import java.util.Scanner;


public class handleExceptions1 {
    public static void main(String[] args) {

        Scanner initial = new Scanner(System.in);
        System.out.println(" Type 'a' to enter the value for side A.\n Type 'b' to enter the value for side B.\n Type 'c' to calculate the hypotenuse.\n Or type 'q' to exit");
        String inputselected = initial.next();

        boolean repeat = true;
        double _sideA = 0;
        while (repeat) {
            try {
                Scanner input = new Scanner(System.in);
                System.out.print("Please enter side A, this may not be 0: ");
                _sideA = input.nextDouble();
                if (_sideA > 0){
                    repeat = false;
                }
            } catch (InputMismatchException e) {
                System.out.print("Error! Please enter a valid number!");
            }
        }
        boolean repeat2= true;
        double _sideB = 0;
        while (repeat2){
            try {
                Scanner input = new Scanner(System.in);
                System.out.print("Please enter side B, this may not be 0: ");
                _sideB = input.nextDouble();
                if (_sideB > 0){
                repeat2= false;
                }
            } catch (InputMismatchException e) {
                System.out.print("Error! Please enter a valid number!");
            }
        }
        double hypotenuse = Math.sqrt((_sideA*_sideA) + (_sideB*_sideB));
        System.out.print("Side C(the hypotenuse) is: "+ hypotenuse);

    }



}

My logic is to put something after "String inputselected = ..." but I'm not sure what. If anyone can help me, it would be greatly appreciated !

Answer 1

sideA = -1;
sideB = -1;
Scanner input = new Scanner(System.in);
do
{
    System.out.println("Enter your choice ( a/b/c/q ) : ");
    char ch = in.nextChar();
    switch(ch)
    {
        case 'a': sideA = in.nextDouble();
                  if(sideA<0) 
                     System.out.println("Error! Please enter a valid number!");
                  break;
        case 'b': sideB = in.nextDouble();
                  if(sideB<0) 
                     System.out.println("Error! Please enter a valid number!");
                  break;
        case 'c': if(sideA<0 || sideB<0) 
                     System.out.println("Other two sides not yet given! please provide a and b first. ");
                  else
                     System.out.print("Side C(the hypotenuse) is: "+ Math.sqrt((_sideA*_sideA) + (_sideB*_sideB)););

                  break;
        case 'q': break;
        default : System.out.println(" Enter a valid choice! ");
    }
}while(ch!='q');