I am having difficulty looping my program back to the beginning to start a new loop

Question

I am writing a code where the user is trying to find the hypotenuse of a Triangle. My code starts by asking the user which side would they like to start with side A or side B. I used the Switch method to cover both case. what i want my code to do after either case is used, is to go back to the starting point, until the user quits. For some reason my code only does one case but doesn't go back to the beginning to start a whole new loop. Am i using the wrong method? Did I write the code improperly? What can i do to fix it?

import java.util.Scanner;

public class HandleException {
public static void main (String[] args){
    int data= 0;
    int data1= 0;
    int sum= 0;

    Scanner input = new Scanner (System.in);
    //ask user for a command
    System.out.println("Which side would you like to start with A or B");
    String s= input.next();
            char letter= s.charAt(0);

                loop:while (letter!= 'q'){      


    switch (letter){

    //if user inputs 'A'
        case 'a':

            System.out.println("Enter value for side A: ");
            data= input.nextInt();
                System.out.println("Enter next command: A : value for side A; B : Value for side B; C: Calculate; Q : Quit program.");
                s=input.next();
                letter=s.charAt(0);
                    if (letter == 'b')
                    System.out.println("Enter Value For side B: ");
                    data1= input.nextInt();
                        System.out.println("Enter next command: A : value for side A; B : Value for side B; C: Calculate; Q : Quit program.");
                        s=input.next();
                        letter=s.charAt(0);
                            if (letter== 'c')
                                sum=data*data+data1*data1;
                                int sumsrt = (int) Math.sqrt(sum);
                                System.out.println("The hypotenuse is:  "+sumsrt);
                                continue;

        //if user inputs 'B'                        
        case 'b':
            System.out.println("Enter value for side B: ");
            data= input.nextInt();
                System.out.println("Enter next command: A : value for side A; B : Value for side B; C: Calculate; Q : Quit program.");
                s=input.next();
                letter=s.charAt(0);
                    if (letter == 'a')
                    System.out.println("Enter Value For side a: ");
                    data1= input.nextInt();
                        System.out.println("Enter next command: A : value for side A; B : Value for side B; C: Calculate; Q : Quit program.");
                        s=input.next();
                        letter=s.charAt(0);
                            if (letter== 'c')
                                sum=data*data+data1*data1;
                                int sumsrt1 = (int) Math.sqrt(sum);
                                System.out.println("The hypotenuse is:  "+sumsrt1); 
                                continue;




    }

}
}
}

Aah. But they are under case 'a' and case 'b'. What if he puts something else? — Makketronix, Jul 05 '16 at 05:49
Frankly what you are doing is hard to follow, and it also looks to me that you are missing some `{` and `}` after ifs. Do you come from python by any chance? — Coderino Javarino, Jul 05 '16 at 05:49
You may also have to create new scanner every time. See http://stackoverflow.com/questions/11871520/how-can-i-read-input-from-the-console-using-the-scanner-class-in-java — Makketronix, Jul 05 '16 at 05:52

score 0 · Answer 1 · answered Jul 05 '16 at 05:53

After first time of loop is end, it goes to the line while(letter!= 'q') and letter value is c

there is no match value in switch, so second time of loop will end and do nothing.

it will keep looping, so you won't have a chance to ask next System.in

score 0 · Answer 2 · answered Jul 05 '16 at 05:57

You are not asking for quit char once done with hypotenuse calculation. Thats why program going in infinite loop not quitting Also you use break once done.

if (letter == 'b')
                    System.out.println("Enter Value For side B: ");
                    data1= input.nextInt();
                        System.out.println("Enter next command: A : value for side A; B : Value for side B; C: Calculate; Q : Quit program.");
                        s=input.next();
                        letter=s.charAt(0);
                            if (letter== 'c')
                                sum=data*data+data1*data1;
                                int sumsrt = (int) Math.sqrt(sum);
                                System.out.println("The hypotenuse is:  "+sumsrt);
                    System.out.println("Press q for quit otherwise enter side ");

                      break;

similarly do it for case 'b' also

score 0 · Accepted Answer · answered Jul 05 '16 at 05:59

Read input again after the switch cases. Try this

import java.util.Scanner;

public class HandleException {
    public static void main(String[] args) {
        int data = 0;
        int data1 = 0;
        int sum = 0;

        Scanner input = new Scanner(System.in);
        // ask user for a command
        System.out.println("Which side would you like to start with A or B");
        String s = input.next();
        char letter = s.charAt(0);

        while (letter != 'q') {

            switch (letter) {

            // if user inputs 'A'
            case 'a':

                System.out.println("Enter value for side A: ");
                data = input.nextInt();
                System.out.println("Enter next command: A : value for side A; B : Value for side B; C: Calculate; Q : Quit program.");
                s = input.next();
                letter = s.charAt(0);
                if (letter == 'b')
                    System.out.println("Enter Value For side B: ");
                data1 = input.nextInt();
                System.out.println("Enter next command: A : value for side A; B : Value for side B; C: Calculate; Q : Quit program.");
                s = input.next();
                letter = s.charAt(0);
                if (letter == 'c')
                    sum = data * data + data1 * data1;
                int sumsrt = (int) Math.sqrt(sum);
                System.out.println("The hypotenuse is:  " + sumsrt);
                break;

                // if user inputs 'B'
            case 'b':
                System.out.println("Enter value for side B: ");
                data = input.nextInt();
                System.out.println("Enter next command: A : value for side A; B : Value for side B; C: Calculate; Q : Quit program.");
                s = input.next();
                letter = s.charAt(0);
                if (letter == 'a')
                    System.out.println("Enter Value For side a: ");
                data1 = input.nextInt();
                System.out.println("Enter next command: A : value for side A; B : Value for side B; C: Calculate; Q : Quit program.");
                s = input.next();
                letter = s.charAt(0);
                if (letter == 'c')
                    sum = data * data + data1 * data1;
                int sumsrt1 = (int) Math.sqrt(sum);
                System.out.println("The hypotenuse is:  " + sumsrt1);
                break;

            }

            System.out.println("Which side would you like to start with A or B");
            s = input.next();
            letter = s.charAt(0);

        }
    }
}

I am having difficulty looping my program back to the beginning to start a new loop

3 Answers3