Java：如何询问用户是否要继续编程

Question

我已经做过，这样它就可以告诉用户输入的是素数还是不是素数，但是现在我必须这样做，以便它询问用户他/她是否想检查另一个数字，并且等待用户输入“ Y”或“ y”为是，输入“ n”或“ N”为否。 如果是，请重复三个步骤。 如果否，请退出程序。 对于所有其他字母，请拒绝ti并要求用户仅输入“ y”或“ n”。

import java.util.*;  // importing package util


public class Prime
{
    public static void main (String args[])
    {
        int num,count=0;
        Scanner scan = new Scanner(System.in); //scanner for input
        System.out.print("Enter any number : ");
        num = scan.nextInt();
        for(int i=2; i <= (num/2); i++) 
        {
            if((num % i) == 0)
            {
                count++;
                break;
            }
        }
        if((count==0) && (num!= 1))
        System.out.println( num + " is a prime number.");
        else
        System.out.println( num + " is not a prime number.");
    }
}

Answer 1

这是我开始编码时学会的一种非常标准的方法。

使用这样的do-while循环：

do
{
 System.out.print("Enter any number : ");
        num = scan.nextInt();
        for(int i=2; i <= (num/2); i++) 
        {
            if((num % i) == 0)
            {
                count++;
                break;
            }
        }
        if((count==0) && (num!= 1))
        System.out.println( num + " is a prime number.");
        else
        System.out.println( num + " is not a prime number.");
        System.out.println("Continue(Y/N)");
        char a = scan.next();

} while(a=='Y'|| a=='y')

如果用户输入其他内容，则循环将中断。 :)

Answer 2

搭配switch case

System.out.print("DO you to continue Y/N: ");
    String answer = scan.nextLine();


    switch (answer)
    {
    case "Y"
    case "y": //WRITE YOUR CODE HERE
             break;
    case "N"
    case "n"://exit from program;
             break;

    default :
             System.out.println("invalid choice")   ;
             break;
    }

Answer 3

String awnser="";
do{

        int num,count=0;
        Scanner scan = new Scanner(System.in); //scanner for input
        System.out.print("Enter any number : ");
        num = scan.nextInt();
        for(int i=2; i <= (num/2); i++) 
        {
            if((num % i) == 0)
            {
                count++;
                break;
            }
        }
        if((count==0) && (num!= 1))
        System.out.println( num + " is a prime number.");
        else
        System.out.println( num + " is not a prime number.");

        System.out.println("do you want to continue?");
        awnser=scan.next();

}while(awnser.equals("y"));

Answer 4

如何使用while循环

while (!"N".equals(inputValues) {
//Keep asking for user inputs

}

Answer 5

你可以试试这个..

import java.util.Scanner;

// importing package util

public class Prime
{
    static Scanner scan = new Scanner(System.in);
    static String userInput = null;

    public static void main(String args[])
    {
        checkPrime();
        while (true)
        {
            System.out.print("Are You Want to Continue (Y/N) ?");
            userInput = scan.next();
            if (userInput.equalsIgnoreCase("Y"))
                checkPrime();
            else if (userInput.equalsIgnoreCase("N"))
            {
                System.out.print("Thank you !!");
                break;
            }
            else{
                            System.out.print("Try Again With (Y/N) only !");   
            }

        }

    }

    public static void checkPrime()
    {
        int num, count = 0;
        System.out.print("Enter any number : ");
        num = scan.nextInt();
        for (int i = 2; i <= (num / 2); i++)
        {
            if ((num % i) == 0)
            {
                count++;
                break;
            }
        }
        if ((count == 0) && (num != 1))
            System.out.println(num + " is a prime number.");
        else
            System.out.println(num + " is not a prime number.");
    }
}

Answer 6

 import java.io.InputStream; import java.util.Scanner; public class example1 { static int value; static int quantity; static int total = 0; static int total_sold = 0; static int total_cashier = 0; static float expensier = 0; int again = 1; static String answer; public static void main(String[] args) { while (true) { System.out.print("Are You Want to Continue (Y/N) ?\\n"); Scanner ans = new Scanner(System.in); answer =ans.nextLine(); if (answer.equalsIgnoreCase("Y")) { Scanner input = new Scanner(System.in); System.out.println("Input Price: \\n"); value = input.nextInt(); Scanner input2 = new Scanner(System.in); System.out.println("Input Quantity: \\n"); quantity = input2.nextInt(); total += value * quantity; total_cashier += total; if (value > expensier) { expensier = value; } total_sold += quantity; } else if (answer.equalsIgnoreCase("N")) { System.out.print("Thank you !!"); break; } else { System.out.print("Try Again With (Y/N) only !"); } System.out.println("Total to pay :" + total); System.out.println("Value of the expensiest product: " + expensier); System.out.println("Amount of products sold: " + total_sold); System.out.println("Amount of cash in cashier: " + total_cashier); } } } 

Answer 7

  private static String reply; public static void main(String[] args){ int num,count=0; Scanner scan = new Scanner (System.in); do { System.out.print("Enter any number : "); num = scan.nextInt(); for(int i=2; i <= (num/2); i++) { if((num % i) == 0) { count++; break; } } if((count==0) && (num!= 1)) System.out.println( num + " is a prime number."); else System.out.println( num + " is not a prime number."); System.out.println("Continue(Y/N)"); reply = scan.next().toUpperCase(); } while(reply.equals("Y")); 

我注意到只做while循环而不是没有代码...

Answer 8

使用此代码

import java.util.*; 

public class stackof
{
public static void main (String args[])
{
    int num,count=0;
    String s="y";
    Scanner scan = new Scanner(System.in); //scanner for input
    System.out.print("Enter any number : ");

    while(s.equalsIgnoreCase("y")){
        num = scan.nextInt();
      for(int i=2; i <= (num/2); i++)
      {
        if((num % i) == 0)
        {
            count++;
            break;
        }
      }

      if((count==0) && (num!= 1))
         System.out.println( num + " is a prime number.");
      else
         System.out.println( num + " is not a prime number.");

      System.out.println( "Do you want to enter another no?");
      s=scan.next();
    }
  }
}