结束这个 do-while 循环？

Question

How do I end the do-while loop when the user enters 0?

The program will continue execution if the user enter F,G,H and J. The program will exit if the user enters 0.

import java.util.Scanner;

public class P4Q5 {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {


        Scanner sc = new Scanner(System.in);
        System.out.println("\nMain Menu: \n" +
                "Enter 0 to exit program\n" +
                "Enter F to display Faith\n" +
                "Enter G to display Grace\n" +
                "Enter H to display Hope\n" +
                "Enter J to display Joy\n");



        do {
             System.out.print("Enter your choice:");
               String s = sc.nextLine();
            char ch = s.charAt(0);
            if (( ch == 'F'))  {
                System.out.println("\nFaith\n");
            }

            else if  (( ch == 'G')) {
                System.out.println("\nGrace\n");
            }

            else if  (( ch == 'H')) {
                System.out.println("\nHope\n");
            }

            else if  (( ch == 'J')) {
                System.out.println("\nJoy\n");
            }



            else  {
                System.out.println("\nWrong option entered!!\n");
            }

        } while (ch == 'O');

              // TODO code application logic here
    }

}

Answer 1

How about while (ch != '0') instead of while (ch == 'O') ? Notice the difference between 0 and O ?

Answer 2

try this in your do while:

if( ch == '0') break;

Answer 3

Try this:

/**
* @param args the command line arguments
*/
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.println("\nMain Menu: \n" +
        "Enter 0 to exit program\n" +
        "Enter F to display Faith\n" +
        "Enter G to display Grace\n" +
        "Enter H to display Hope\n" +
        "Enter J to display Joy\n");



do {
     System.out.print("Enter your choice:");
       String s = sc.nextLine();
    char ch = s.charAt(0);
    if (( ch == 'F'))  {
        System.out.println("\nFaith\n");
    }

    else if  (( ch == 'G')) {
        System.out.println("\nGrace\n");
    }

    else if  (( ch == 'H')) {
        System.out.println("\nHope\n");
    }

    else if  (( ch == 'J')) {
        System.out.println("\nJoy\n");
    }

    else if (( ch == 'O' )) {
        System.exit();
    }

    else  {
        System.out.println("\nWrong option entered!!\n");
    }

} while (ch == 'F' || ch == 'G' || ch == 'H' || ch == 'J' || ch == 'O');

      // TODO code application logic here

}

To exit program you need to do System.exit()

To exit loop do as @bitmask stated

Answer 4

I would use a boolean variable, if you enter 0 the boolean becomes true, and then do a check on the boolean...

    boolean bool = false;
    do {
         ...

        if(input == '0')
           bool=true;
    } while (!bool);

oh and before i forget, i would also do one input before the do while, and one at the end of the loop. Like that, your whole code won't be run again after you hit 0.