是/否，布尔值还是 if/else？

Question

I'm having issues creating a yes/no input in my program. I want the user to be able to input ay/n after the last print statement, but i'm not quite sure how I would implement it. I know it would most likely include a boolean or an if/else statement, but i'm not quite sure. Any help?

import java.util.*;
import java.io.*; 
import java.util.Scanner;

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

    int age;
    String name;

    Scanner scan = new Scanner(System.in);

    System.out.println("Enter in your age.");
    age = scan.nextInt();

        if (age >= 10 && age < 18) 
        {
            System.out.println("So you're a kid, huh?");
        } 

        else if (age < 10)
        {
            System.out.println("Nice try.");
            System.exit(0);
        }
        else if (age >= 18 && age <= 100)
        {
            System.out.println("So you're an adult, huh?");
        }
        else if (age > 100)
        {
            System.out.println("Nice try.");
            System.exit(0);
        }

        Scanner in = new Scanner(System.in);
        System.out.println("Enter in your name");
        name = in.nextLine();

        System.out.println("So you're " + age + " years old and your name is " + name + "?");

        System.out.println("y/n");
        }
}

Answer 1

String answer;
boolean yn;

System.out.println("y/n");
while (true) {
  answer = in.nextLine().trim().toLowerCase();
  if (answer.equals("y")) {
    yn = true;
    break;
  } else if (answer.equals("n")) {
    yn = false;
    break;
  } else {
     System.out.println("Sorry, I didn't catch that. Please answer y/n");
  }
}

Answer 2

Is this what you need?

String answer = in.nextLine()
Boolean yn = (answer.equalsIgnoreCase("Y") ? true : false);

Or, you can use a shorter form:

Boolean yn = (answer.equalsIgnoreCase("Y"));

If you meant something else please post a clarification.

Answer 3

just add boolean answer = in.nextLine().toLowerCase().startsWith("y");

So basically it sets answer to true if you type anything that starts with y . false otherwise.

Answer 4

You would read in a string and compare it to the literal "y". The comparison yields a boolean.

You can expand this to first checking if it's "y" or "n" and complain if it's neither or narrow it to accept other equivalents like "yes" and "no".

In any case, your boolean is achieved by comparing to a literal.

Answer 5

试试这个，

boolean answer = "y".equalsIgnoreCase(in.nextLine());

Answer 6

You can use do while loop for this like:

import java.util.Scanner;

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

        int age;
        String name;
        String input = "y";
        do {
            Scanner scan = new Scanner(System.in);

            System.out.println("Enter in your age.");
            age = scan.nextInt();

            if (age >= 10 && age < 18) {
                System.out.println("So you're a kid, huh?");
            }

            else if (age < 10) {
                System.out.println("Nice try.");
                System.exit(0);
            } else if (age >= 18 && age <= 100) {
                System.out.println("So you're an adult, huh?");
            } else if (age > 100) {
                System.out.println("Nice try.");
                System.exit(0);
            }

            Scanner in = new Scanner(System.in);
            System.out.println("Enter in your name");
            name = in.nextLine();

            System.out.println("So you're " + age
                    + " years old and your name is " + name + "?");

            Scanner sc = new Scanner(System.in);
            System.out.println("y/n");
            input = sc.nextLine();
        } while (input.equalsIgnoreCase("y"));
    }
}

Answer 7

I got this figured out.

import java.util.Scanner;

public class MuseumHours2 {
    public static void main(String[] args) {
        String day;
        boolean yn = true;
        boolean userContinue;
        String answer;

        Scanner stdIn = new Scanner(System.in);


        do {
            System.out.println("Hello, thank you for visiting the Museum 
    website. For what day would you like to check our hours of operation?");
            day = stdIn.nextLine();

            System.out.println("Is today a holiday? Enter y or n.");
            answer = stdIn.nextLine();
                if (answer.equals("y")) {
                    yn = true;
                } else if (answer.equals("n")) {
                    yn = false;
                } else { 
                    System.out.println("Sorry, I didn't understand. Please reply y or n.");
                }

            switch (day) {
            case "Monday":
                System.out.println("Closed.");
                break;

            case "Tuesday":
                if (yn) {
                    System.out.println("We are open from 1:00 to 4:00.");
                } else {
                    System.out.println("We are open from 12:00 to 5:00.");
                }
                break;
            case "Wednesday":
                if (yn) {
                    System.out.println("We are open from 2:00 to 5:00.");
                } else { 
                    System.out.println("We are open from 1:00 to 6:00.");
                    break;
                }
            case "Thursday":
                System.out.println("Closed.");
                break;
                }
            System.out.println("Do you want to re-run the program? Type y or n.");
        } while (userContinue = "y".equalsIgnoreCase(stdIn.nextLine()));
    }
}

Answer 8

Here is an example

 public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);
        boolean yn;
        String ageq;

        System.out.println("Please enter your age: ");
        ageq = sc.next();

        System.out.println("You entered " + ageq + " is this correct?");
        System.out.println("y/n");
        OUTER:
        while (true) {
            ageq = sc.next().trim().toLowerCase();
            switch (ageq) {
                case "y":
                    yn = true;
                    break OUTER;
                case "n":
                    yn = false;
                    break OUTER;
                default:
                    System.out.println("Sorry, I didn't get that. Please enter y/n");
                    break;
            }
        }

  }

Answer 9

使用org.apache.commons.lang3.BooleanUtils.toBooleanObject() ，它会为 'Yes' & 'Y' 返回 true